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Spring-IoC容器源码导读
1.几个重要类/接口
阅读前的准备
- 源码下载：
- 源码版本：v5.2.1.RELEASE
1.1 BeanFactory 顶级接口（低配版的IoC容器）
BeanFactory接口定义说明
- BeanFactory是低配版的IoC容器，定义了Ioc容器基本的功能
完整版源码：
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BeanFactory方法属性摘要
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1.2 HierarchicalBeanFactory接口
完整版源码：
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HierarchicalBeanFactory方法属性摘要
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1.3 ListableBeanFactory接口
完整版源码：
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ListableBeanFactory方法属性摘要
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1.4 ApplicationContext接口
ApplicationContext接口解析
- 相比于BeanFactory,ApplicationContext是高配版的Ioc容器，其在BeanFactory的基础上实现了更加复杂的扩展功能
- ListableBeanFactory, HierarchicalBeanFactory都是BeanFactory的子接口，ApplicationContext继承了这两个接口，ApplicationContext进一步扩展了BeanFactory接口的功能
- . . .
完整版源码：
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ApplicationContext方法属性摘要
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1.5 BeanDefination接口
BeanDefination接口定义解析
- BeanDefination用于管理Ioc容器中JavaBean与JavaBean之间的依赖关系，其抽象了Java开发人员对于JavaBean的定义
- Spring将开发人员定义的JavaBean的数据结构转化为内存中的BeanDefination数据结构进行维护
完整版源码：
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BeanDefination方法属性摘要
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2.从一个Demo程序开始
2.1 Demo项目配置
maven的pom.xml配置文件
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2.2 Demo程序
2.2.1启动类
- 代码位置:com.acanx.spring.xml.CspringIocConfigByFileSystemXmlApplicationContext.java
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package com.acanx.spring.xml;
import com.acanx.spring.bean.Car;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.FileSystemXmlApplicationContext;
/**
* ACANX-JavaWeb / com.acanx.spring.xml / SpringIocConfigByXmlFileInClassPath.java
* 文件由 ACANX 创建于 2019/7/30 - 13:39
* Description SpringIocConfigByXmlFileInClassPath:
* 补充说明： 使用FileSystemXmlApplicationContext加载文件系统下的配置文件
*
* @author ACANX
* @version 0.0.1.0
* @date 2019/7/30 13:39
* @since 0.0.1-SNAPSHOT
*/
public class CspringIocConfigByFileSystemXmlApplicationContext {
private static final Logger logger= LoggerFactory.getLogger(CspringIocConfigByFileSystemXmlApplicationContext.class);
public static void main(String[] args) {
logger.info("-------------------");
logger.info(System.getProperty("org.apache.commons.logging.LogFactory"));
logger.info(System.getProperty("org.apache.commons.logging.Log"));
logger.info("-------------------");
String location="D:\\ProgramCode\\JavaCode\\ACANX-JavaWeb\\JavaWeb-Spring\\ApplicationContextC.xml";
ApplicationContext applicationContext = new FileSystemXmlApplicationContext(location);
Car car = (Car) applicationContext.getBean("myCar");
logger.info(car.toString());
logger.info("Info :{}",logger.isInfoEnabled());
String[] beanNames=applicationContext.getBeanDefinitionNames();
for (String beanName:beanNames) {
logger.info(beanName+"::::: "+applicationContext.getBean(beanName).toString());
}
}
}
2.2.2使用到的Bena对象
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2.2.3 springContext的xml文件ApplicationContextC.xml
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2.2.4 配置日志 logback.xml（resources文件夹下）
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3.Spring IOC容器的创建
3.1 进入FileSystemXmlApplicationContext（AbstractXmlApplicationContext抽象类的具体实现类）
- 代码位置: org.springframework.context.support.FileSystemXmlApplicationContext.java
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16public FileSystemXmlApplicationContext(String configLocation) throws BeansException {
this(new String[] {configLocation}, true, null);
}
// 上面的this 来到下面的重载构造方法
public FileSystemXmlApplicationContext(
String[] configLocations, boolean refresh, @Nullable ApplicationContext parent)
throws BeansException {
super(parent); // 初始化父容器AbstractApplicationContext
setConfigLocations(configLocations); // 设置资源文件的位置
if (refresh) {
refresh();// 核心方法，具体定义在超类AbstractApplicationContext（抽象类）中，是一个模板方法
}
}
3.2 初始化父容器AbstractApplicationContext
3.2.1 AbstractXmlApplicationContext抽象类（FileSystemXmlApplicationContext的父类）
- 代码位置: org.springframework.context.support.AbstractXmlApplicationContext.java
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4public AbstractXmlApplicationContext(@Nullable ApplicationContext parent) {
super(parent);
}
3.2.2 AbstractRefreshableConfigApplicationContext抽象类（ AbstractXmlApplicationContext的父类）
- 代码位置:org.springframework.context.support.AbstractRefreshableConfigApplicationContext.java
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4public AbstractRefreshableConfigApplicationContext(@Nullable ApplicationContext parent) {
super(parent);
}
3.2.3 AbstractRefreshableApplicationContext抽象类
- 代码位置:org.springframework.context.support.AbstractRefreshableApplicationContext.java
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4public AbstractRefreshableApplicationContext(@Nullable ApplicationContext parent) {
super(parent);
}
3.2.4 AbstractApplicationContext抽象类
- 代码位置:org.springframework.context.support.AbstractApplicationContext.java
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27public AbstractApplicationContext(@Nullable ApplicationContext parent) {
this();
setParent(parent);
}
//上面对应的this()方法
public AbstractApplicationContext() {
this.resourcePatternResolver = getResourcePatternResolver();
}
//上面对应的 getResourcePatternResolver()方法
protected ResourcePatternResolver getResourcePatternResolver() {
return new PathMatchingResourcePatternResolver(this);
}
// this()之后的setParent(parent);方法
@Override
public void setParent(@Nullable ApplicationContext parent) {
this.parent = parent;
if (parent != null) {
Environment parentEnvironment = parent.getEnvironment();
if (parentEnvironment instanceof ConfigurableEnvironment) {
getEnvironment().merge((ConfigurableEnvironment) parentEnvironment);
}
}
}
3.5 PathMatchingResourcePatternResolver类
- PathMatchingResourcePatternResolver(this)对应的构造方法
- 代码位置:org.springframework.core.io.support.PathMatchingResourcePatternResolver.java
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5public PathMatchingResourcePatternResolver(ResourceLoader resourceLoader) {
Assert.notNull(resourceLoader, "ResourceLoader must not be null");
this.resourceLoader = resourceLoader;
}
4.setConfigLocations(String… locations) 方法
- 设置资源文件的位置
4.1 AbstractRefreshableConfigApplicationContext.setConfigLocations(@Nullable String… locations) 方法
- 代码位置:org.springframework.context.support.AbstractRefreshableConfigApplicationContext.java
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14public void setConfigLocations(@Nullable String... locations) {
if (locations != null) {
Assert.noNullElements(locations, "Config locations must not be null");
this.configLocations = new String[locations.length];
for (int i = 0; i < locations.length; i++) {
this.configLocations[i] = resolvePath(locations[i]).trim();
}
}
else {
this.configLocations = null;
}
}
5. refresh()方法
- AbstractApplicationContext抽象类中定义的refresh()模板方法
- 定义了需要执行刷新操作的一些步骤，只是一个模板，个性化的逻辑由其子类来具体实现
5.1 refresh()方法定义
- 代码位置:org.springframework.context.support.AbstractApplicationContext.java
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67@Override
public void refresh() throws BeansException, IllegalStateException {
synchronized (this.startupShutdownMonitor) {
// Prepare this context for refreshing.
prepareRefresh();
// Tell the subclass to refresh the internal bean factory.
// 创建BeanFactory
ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
// Prepare the bean factory for use in this context.
prepareBeanFactory(beanFactory);
try {
// Allows post-processing of the bean factory in context subclasses.
postProcessBeanFactory(beanFactory);
// Invoke factory processors registered as beans in the context.
invokeBeanFactoryPostProcessors(beanFactory);
// Register bean processors that intercept bean creation.
registerBeanPostProcessors(beanFactory);
// Initialize message source for this context.
initMessageSource();
// Initialize event multicaster for this context.
initApplicationEventMulticaster();
// Initialize other special beans in specific context subclasses.
onRefresh();
// Check for listener beans and register them.
registerListeners();
// Instantiate all remaining (non-lazy-init) singletons.
// 实例化Bean
finishBeanFactoryInitialization(beanFactory);
// Last step: publish corresponding event.
finishRefresh();
}
catch (BeansException ex) {
if (logger.isWarnEnabled()) {
logger.warn("Exception encountered during context initialization - " +
"cancelling refresh attempt: " + ex);
}
// Destroy already created singletons to avoid dangling resources.
destroyBeans();
// Reset 'active' flag.
cancelRefresh(ex);
// Propagate exception to caller.
throw ex;
}
finally {
// Reset common introspection caches in Spring's core, since we
// might not ever need metadata for singleton beans anymore...
resetCommonCaches();
}
}
}
5.2 prepareRefresh()方法
- 正式Refresh()操作前的准备工作
- 代码位置:org.springframework.context.support.AbstractApplicationContext.java
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42protected void prepareRefresh() {
// Switch to active.
this.startupDate = System.currentTimeMillis();
this.closed.set(false);
this.active.set(true);
if (logger.isDebugEnabled()) {
if (logger.isTraceEnabled()) {
logger.trace("Refreshing " + this);
}
else {
logger.debug("Refreshing " + getDisplayName());
}
}
// Initialize any placeholder property sources in the context environment.
initPropertySources();
// Validate that all properties marked as required are resolvable:
// see ConfigurablePropertyResolver#setRequiredProperties
getEnvironment().validateRequiredProperties();
// Store pre-refresh ApplicationListeners...
if (this.earlyApplicationListeners == null) {
this.earlyApplicationListeners = new LinkedHashSet<>(this.applicationListeners);
}
else {
// Reset local application listeners to pre-refresh state.
this.applicationListeners.clear();
this.applicationListeners.addAll(this.earlyApplicationListeners);
}
// Allow for the collection of early ApplicationEvents,
// to be published once the multicaster is available...
this.earlyApplicationEvents = new LinkedHashSet<>();
}
// 上述定义的initPropertySources()方法，具体由子类实现
protected void initPropertySources() {
// For subclasses: do nothing by default.
}
5.3 obtainFreshBeanFactory()方法
- 创建BeanFactory的核心方法
- 代码位置:org.springframework.context.support.AbstractApplicationContext.java
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9protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {
refreshBeanFactory();// 刷新BeanFactory，抽象方法由其子类实现,5.3.1中有说明
return getBeanFactory();// 获取BeanFactory，父类的抽象方法继承并由其子类实现
}
protected abstract void refreshBeanFactory() throws BeansException, IllegalStateException;
@Override // 该方法在ConfigurableApplicationContext接口中定义
public abstract ConfigurableListableBeanFactory getBeanFactory() throws IllegalStateException;
5.3.1 refreshBeanFactory()方法的一种实现
- org.springframework.context.support.AbstractRefreshableApplicationContext中的具体实现如下
- refreshBeanFactory()方法是AbstractApplicationContext中定义的抽象方法
- AbstractRefreshableApplicationContext中的refreshBeanFactory()方法是该抽象方法的一个具体实现
- 主要作用：刷新BeanFactory
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48// AbstractRefreshableApplicationContext中refreshBeanFactory()方法的一种实现
@Override
protected final void refreshBeanFactory() throws BeansException {
// 检查上下文中是否已存在BeanFactory
if (hasBeanFactory()) {
// 存在BeanFactory时先销毁已存在的BeanFactory
destroyBeans();//调用AbstractApplicationContext中的实现
/**
* 以下是AbstractApplicationContext中destroyBeans()方法的实现
* protected void destroyBeans() {
* getBeanFactory().destroySingletons();
* }
*/
closeBeanFactory();// 调用本抽象类中的closeBeanFactory()方法，具体代码在下面列出
}
try {
// 创建新的BeanFactory
// 下面这行代码只会创建一个空的BeanFactory，并未有任何Bean
DefaultListableBeanFactory beanFactory = createBeanFactory();
beanFactory.setSerializationId(getId());
customizeBeanFactory(beanFactory);
loadBeanDefinitions(beanFactory);// refreshBeanFactory()方法实现的核心
synchronized (this.beanFactoryMonitor) {
this.beanFactory = beanFactory;
}
}
catch (IOException ex) {
throw new ApplicationContextException("I/O error parsing bean definition source for " + getDisplayName(), ex);
}
}
// AbstractRefreshableApplicationContext抽象类中refreshBeanFactory()方法内调用的closeBeanFactory()方法
@Override
protected final void closeBeanFactory() {
synchronized (this.beanFactoryMonitor) {
if (this.beanFactory != null) {
//销毁已存在的BeanFactory
this.beanFactory.setSerializationId(null);
this.beanFactory = null;
}
}
}
//AbstractRefreshableApplicationContext抽象类中refreshBeanFactory()方法内调用createBeanFactory()方法
protected DefaultListableBeanFactory createBeanFactory() {
// 调用下面 AbstractApplicationContext中的getInternalParentBeanFactory()方法
return new DefaultListableBeanFactory(getInternalParentBeanFactory());
}
AbstractApplicationContext中的getInternalParentBeanFactory()方法
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DefaultListableBeanFactory的构造方法
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DefaultListableBeanFactory父类AbstractAutowireCapableBeanFactory(抽象类)的构造方法
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AbstractRefreshableApplicationContext中的customizeBeanFactory(beanFactory)方法
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AbstractRefreshableApplicationContext中的loadBeanDefinitions(beanFactory)方法
- 是实现refreshBeanFactory()方法的核心
- org.springframework.context.support.AbstractRefreshableApplicationContext中定义的抽象方法
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2protected abstract void loadBeanDefinitions(DefaultListableBeanFactory beanFactory)
throws BeansException, IOException; - 该抽象方法的一个具体实现在org.springframework.context.support.AbstractXmlApplicationContext中
org.springframework.context.support.AbstractXmlApplicationContext中的loadBeanDefinitions(DefaultListableBeanFactory beanFactory)方法
- org.springframework.context.support.AbstractRefreshableApplicationContext中定义的抽象方法loadBeanDefinitions(DefaultListableBeanFactory beanFactory)的一个实现
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18@Override
protected void loadBeanDefinitions(DefaultListableBeanFactory beanFactory) throws BeansException, IOException {
// Create a new XmlBeanDefinitionReader for the given BeanFactory.
// 通过上一步创建的空BeanFactory来创建新的XmlBeanDefinitionReader对象
// XmlBeanDefinitionReader用于解析xml文件中定义的bean
XmlBeanDefinitionReader beanDefinitionReader = new XmlBeanDefinitionReader(beanFactory); //
// Configure the bean definition reader with this context's
// resource loading environment.
beanDefinitionReader.setEnvironment(this.getEnvironment());
beanDefinitionReader.setResourceLoader(this);
beanDefinitionReader.setEntityResolver(new ResourceEntityResolver(this));
// Allow a subclass to provide custom initialization of the reader,
// then proceed with actually loading the bean definitions.
initBeanDefinitionReader(beanDefinitionReader);
loadBeanDefinitions(beanDefinitionReader); //这是一个重载方法，入参是上面生成的beanDefinitionReader
}
new XmlBeanDefinitionReader(beanFactory)
- XmlBeanDefinitionReader(beanFactory)构造方法调用其父类AbstractBeanDefinitionReader的构造方法，具体如下
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20protected AbstractBeanDefinitionReader(BeanDefinitionRegistry registry) {
Assert.notNull(registry, "BeanDefinitionRegistry must not be null");
this.registry = registry;
// Determine ResourceLoader to use.
if (this.registry instanceof ResourceLoader) {
this.resourceLoader = (ResourceLoader) this.registry;
}
else {
this.resourceLoader = new PathMatchingResourcePatternResolver();
}
// Inherit Environment if possible
if (this.registry instanceof EnvironmentCapable) {
this.environment = ((EnvironmentCapable) this.registry).getEnvironment();
}
else {
this.environment = new StandardEnvironment();
}
}
AbstractXmlApplicationContext抽象类中的initBeanDefinitionReader(beanDefinitionReader)方法
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AbstractXmlApplicationContext抽象类中的loadBeanDefinitions(XmlBeanDefinitionReader reader)方法
- 主要功能是解析资源文件的位置
- 调用XmlBeanDefinitionReader对象的loadBeanDefinitions方法解析bean的定义
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10protected void loadBeanDefinitions(XmlBeanDefinitionReader reader) throws BeansException, IOException {
Resource[] configResources = getConfigResources();
if (configResources != null) {
reader.loadBeanDefinitions(configResources); //具体调用AbstractBeanDefinitionReader中实现的loadBeanDefinitions(Resource... resources)方法
}
String[] configLocations = getConfigLocations();
if (configLocations != null) {
reader.loadBeanDefinitions(configLocations);//具体调用AbstractBeanDefinitionReader中实现的loadBeanDefinitions(String... locations)
}
}
reader.loadBeanDefinitions(configResources)方法与reader.loadBeanDefinitions(configLocations)方法
- XmlBeanDefinitionReader对象的loadBeanDefinitions方法用于解析bean的定义
- reader是XmlBeanDefinitionReader类型的对象，loadBeanDefinitions方法定义在BeanDefinitionReader接口中，
- loadBeanDefinitions方法具体是在AbstractBeanDefinitionReader抽象类中实现的，具体代码如下：
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22@Override
public int loadBeanDefinitions(Resource... resources) throws BeanDefinitionStoreException {
Assert.notNull(resources, "Resource array must not be null");
int count = 0;
// 遍历每一个资源并依次调用重载方法loadBeanDefinitions(Resource resource)，定义在XmlBeanDefinitionReader中，具体实现在XmlBeanDefinitionReader中
for (Resource resource : resources) {
count += loadBeanDefinitions(resource);//
}
return count;
}
@Override
public int loadBeanDefinitions(String... locations) throws BeanDefinitionStoreException {
Assert.notNull(locations, "Location array must not be null");
int count = 0;
//遍历资源数组，调用重载方法loadBeanDefinitions(String location)
for (String location : locations) {
count += loadBeanDefinitions(location);//
}
return count;
}
count += loadBeanDefinitions(resource)中的loadBeanDefinitions(resource)方法
- loadBeanDefinitions(resource)方法在BeanDefinitionReader接口中定义，具体实现是在XmlBeanDefinitionReader中
- XmlBeanDefinitionReader中的实现代码如下：
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4@Override
public int loadBeanDefinitions(Resource resource) throws BeanDefinitionStoreException {
return loadBeanDefinitions(new EncodedResource(resource));
} - 可以看到，上面的方法又调用了loadBeanDefinitions(new EncodedResource(resource))方法，该方法在BeanDefinitionReader接口中定义，具体实现在XmlBeanDefinitionReader中,具体实现，详细代码如下：
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40public int loadBeanDefinitions(EncodedResource encodedResource) throws BeanDefinitionStoreException {
Assert.notNull(encodedResource, "EncodedResource must not be null");
if (logger.isTraceEnabled()) {
logger.trace("Loading XML bean definitions from " + encodedResource);
}
Set<EncodedResource> currentResources = this.resourcesCurrentlyBeingLoaded.get();
if (currentResources == null) {
currentResources = new HashSet<>(4);
this.resourcesCurrentlyBeingLoaded.set(currentResources);
}
if (!currentResources.add(encodedResource)) {
throw new BeanDefinitionStoreException("Detected cyclic loading of " + encodedResource + " - check your import definitions!");
}
try {
//以流的形式读取资源文件
InputStream inputStream = encodedResource.getResource().getInputStream();
try {
InputSource inputSource = new InputSource(inputStream);
if (encodedResource.getEncoding() != null) {
inputSource.setEncoding(encodedResource.getEncoding());
}
// 调用doLoadBeanDefinitions解析载入文件中的bean定义
return doLoadBeanDefinitions(inputSource, encodedResource.getResource());
}
finally {
inputStream.close();
}
}
catch (IOException ex) {
throw new BeanDefinitionStoreException(
"IOException parsing XML document from " + encodedResource.getResource(), ex);
}
finally {
currentResources.remove(encodedResource);
if (currentResources.isEmpty()) {
this.resourcesCurrentlyBeingLoaded.remove();
}
}
}
count += loadBeanDefinitions(location)中的loadBeanDefinitions(location)方法
- loadBeanDefinitions(location)方法的具体实现AbstractBeanDefinitionReader中；
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5@Override
public int loadBeanDefinitions(String location) throws BeanDefinitionStoreException {
return loadBeanDefinitions(location, null);
} - 解析资源文件的路径，得到Resource[]资源数组
- 上面AbstractBeanDefinitionReader中的loadBeanDefinitions(String location)方法又调用了同类里面的一个重载方法loadBeanDefinitions(String location, @Nullable Set
actualResources) 具体实现如下： 1
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39public int loadBeanDefinitions(String location, @Nullable Set<Resource> actualResources) throws BeanDefinitionStoreException {
ResourceLoader resourceLoader = getResourceLoader();
if (resourceLoader == null) {
throw new BeanDefinitionStoreException(
"Cannot load bean definitions from location [" + location + "]: no ResourceLoader available");
}
if (resourceLoader instanceof ResourcePatternResolver) {
// Resource pattern matching available.
try {
Resource[] resources = ((ResourcePatternResolver) resourceLoader).getResources(location);
//下一行的核心逻辑 调用上面提到的重载方法loadBeanDefinitions(Resource resource)
int count = loadBeanDefinitions(resources);
if (actualResources != null) {
Collections.addAll(actualResources, resources);
}
if (logger.isTraceEnabled()) {
logger.trace("Loaded " + count + " bean definitions from location pattern [" + location + "]");
}
return count;
}
catch (IOException ex) {
throw new BeanDefinitionStoreException(
"Could not resolve bean definition resource pattern [" + location + "]", ex);
}
}
else {
// Can only load single resources by absolute URL.
Resource resource = resourceLoader.getResource(location);
int count = loadBeanDefinitions(resource);
if (actualResources != null) {
actualResources.add(resource);
}
if (logger.isTraceEnabled()) {
logger.trace("Loaded " + count + " bean definitions from location [" + location + "]");
}
return count;
}
}
XmlBeanDefinitionReader类中的doLoadBeanDefinitions(InputSource inputSource, Resource resource)方法
- 该方法是载入定义bean的核心方法
- 代码位置：org.springframework.beans.factory.xml.XmlBeanDefinitionReader
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46protected int doLoadBeanDefinitions(InputSource inputSource, Resource resource)
throws BeanDefinitionStoreException {
try {
// 解析XML文档
Document doc = doLoadDocument(inputSource, resource);
// 下面一行代码 注册Bean
int count = registerBeanDefinitions(doc, resource);
if (logger.isDebugEnabled()) {
logger.debug("Loaded " + count + " bean definitions from " + resource);
}
return count;
}
catch (BeanDefinitionStoreException ex) {
throw ex;
}
catch (SAXParseException ex) {
throw new XmlBeanDefinitionStoreException(resource.getDescription(),
"Line " + ex.getLineNumber() + " in XML document from " + resource + " is invalid", ex);
}
catch (SAXException ex) {
throw new XmlBeanDefinitionStoreException(resource.getDescription(),
"XML document from " + resource + " is invalid", ex);
}
catch (ParserConfigurationException ex) {
throw new BeanDefinitionStoreException(resource.getDescription(),
"Parser configuration exception parsing XML from " + resource, ex);
}
catch (IOException ex) {
throw new BeanDefinitionStoreException(resource.getDescription(),
"IOException parsing XML document from " + resource, ex);
}
catch (Throwable ex) {
throw new BeanDefinitionStoreException(resource.getDescription(),
"Unexpected exception parsing XML document from " + resource, ex);
}
}
// 注册Bean的方法
public int registerBeanDefinitions(Document doc, Resource resource) throws BeanDefinitionStoreException {
BeanDefinitionDocumentReader documentReader = createBeanDefinitionDocumentReader();
int countBefore = getRegistry().getBeanDefinitionCount();
// 注册bean的核心逻辑
documentReader.registerBeanDefinitions(doc, createReaderContext(resource));
return getRegistry().getBeanDefinitionCount() - countBefore;
}
DefaultBeanDefinitionDocumentReader.registerBeanDefinitions(Document doc, XmlReaderContext readerContext)
- 功能：
- 代码位置：org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader
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105@Override
public void registerBeanDefinitions(Document doc, XmlReaderContext readerContext) {
this.readerContext = readerContext;
// 核心逻辑
doRegisterBeanDefinitions(doc.getDocumentElement());
}
// registerBeanDefinitions方法中调用的doRegisterBeanDefinitions方法
@SuppressWarnings("deprecation") // for Environment.acceptsProfiles(String...)
protected void doRegisterBeanDefinitions(Element root) {
// Any nested <beans> elements will cause recursion in this method. In
// order to propagate and preserve <beans> default-* attributes correctly,
// keep track of the current (parent) delegate, which may be null. Create
// the new (child) delegate with a reference to the parent for fallback purposes,
// then ultimately reset this.delegate back to its original (parent) reference.
// this behavior emulates a stack of delegates without actually necessitating one.
BeanDefinitionParserDelegate parent = this.delegate;
this.delegate = createDelegate(getReaderContext(), root, parent);
if (this.delegate.isDefaultNamespace(root)) {
String profileSpec = root.getAttribute(PROFILE_ATTRIBUTE);
if (StringUtils.hasText(profileSpec)) {
String[] specifiedProfiles = StringUtils.tokenizeToStringArray(
profileSpec, BeanDefinitionParserDelegate.MULTI_VALUE_ATTRIBUTE_DELIMITERS);
// We cannot use Profiles.of(...) since profile expressions are not supported
// in XML config. See SPR-12458 for details.
if (!getReaderContext().getEnvironment().acceptsProfiles(specifiedProfiles)) {
if (logger.isDebugEnabled()) {
logger.debug("Skipped XML bean definition file due to specified profiles [" + profileSpec +
"] not matching: " + getReaderContext().getResource());
}
return;
}
}
}
preProcessXml(root);
// 核心逻辑
parseBeanDefinitions(root, this.delegate);
postProcessXml(root);
this.delegate = parent;
}
// 上面方法中调用的parseBeanDefinitions(root, this.delegate)对应的方法实现
protected void parseBeanDefinitions(Element root, BeanDefinitionParserDelegate delegate) {
if (delegate.isDefaultNamespace(root)) {
NodeList nl = root.getChildNodes();
for (int i = 0; i < nl.getLength(); i++) {
Node node = nl.item(i);
if (node instanceof Element) {
Element ele = (Element) node;
if (delegate.isDefaultNamespace(ele)) {
// 本方法的核心逻辑
parseDefaultElement(ele, delegate);
}
else {
delegate.parseCustomElement(ele);
}
}
}
}
else {
delegate.parseCustomElement(root);
}
}
// 上述方法调用的parseDefaultElement(ele, delegate);的具体实现
// 根据bean配置的不同，进入不同分支
private void parseDefaultElement(Element ele, BeanDefinitionParserDelegate delegate) {
if (delegate.nodeNameEquals(ele, IMPORT_ELEMENT)) {
importBeanDefinitionResource(ele);
}
else if (delegate.nodeNameEquals(ele, ALIAS_ELEMENT)) {
processAliasRegistration(ele);
}
else if (delegate.nodeNameEquals(ele, BEAN_ELEMENT)) {
// 本文示例会进入该方法
processBeanDefinition(ele, delegate);
}
else if (delegate.nodeNameEquals(ele, NESTED_BEANS_ELEMENT)) {
// recurse
doRegisterBeanDefinitions(ele);
}
}
// 上述方法最后进入processBeanDefinition(ele, delegate)后的处理过程：
protected void processBeanDefinition(Element ele, BeanDefinitionParserDelegate delegate) {
BeanDefinitionHolder bdHolder = delegate.parseBeanDefinitionElement(ele);
if (bdHolder != null) {
bdHolder = delegate.decorateBeanDefinitionIfRequired(ele, bdHolder);
try {
// Register the final decorated instance.
// 注册Bean的关键代码
BeanDefinitionReaderUtils.registerBeanDefinition(bdHolder, getReaderContext().getRegistry());
}
catch (BeanDefinitionStoreException ex) {
getReaderContext().error("Failed to register bean definition with name '" +
bdHolder.getBeanName() + "'", ele, ex);
}
// Send registration event.
getReaderContext().fireComponentRegistered(new BeanComponentDefinition(bdHolder));
}
}
BeanDefinitionReaderUtils的registerBeanDefinition(bdHolder, getReaderContext().getRegistry())方法
- 主要作用：
- 代码位置：org.springframework.beans.factory.support.BeanDefinitionReaderUtils
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20public static void registerBeanDefinition(
BeanDefinitionHolder definitionHolder, BeanDefinitionRegistry registry)
throws BeanDefinitionStoreException {
// Register bean definition under primary name.
String beanName = definitionHolder.getBeanName();
// 将Bean的名字和BeanDefinition对象进行注册
// registerBeanDefinition(beanName, definitionHolder.getBeanDefinition());方法定义在BeanDefinitionRegistry接口中：
// 具体实现在中实现
registry.registerBeanDefinition(beanName, definitionHolder.getBeanDefinition());
// Register aliases for bean name, if any.
String[] aliases = definitionHolder.getAliases();
if (aliases != null) {
for (String alias : aliases) {
registry.registerAlias(beanName, alias);
}
}
}
DefaultListableBeanFactory中registerBeanDefinition(String beanName, BeanDefinition beanDefinition)
- 作用：
- DefaultListableBeanFactory的字段beanDefinitionMap是一个ConcurrentHashMap<String, BeanDefinition>，用于存储bean的定义信息
- DefaultListableBeanFactory的字段beanDefinitionNames是一个ArrayList
类型数据，用于存储Bean的名称 - 代码位置：org.springframework.beans.factory.support.DefaultListableBeanFactory
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80@Override
public void registerBeanDefinition(String beanName, BeanDefinition beanDefinition)
throws BeanDefinitionStoreException {
Assert.hasText(beanName, "Bean name must not be empty");
Assert.notNull(beanDefinition, "BeanDefinition must not be null");
if (beanDefinition instanceof AbstractBeanDefinition) {
try {
((AbstractBeanDefinition) beanDefinition).validate();
}
catch (BeanDefinitionValidationException ex) {
throw new BeanDefinitionStoreException(beanDefinition.getResourceDescription(), beanName,
"Validation of bean definition failed", ex);
}
}
BeanDefinition existingDefinition = this.beanDefinitionMap.get(beanName);
// 查找是否存在同名的bean
if (existingDefinition != null) {
// 有同名的bean存在时
if (!isAllowBeanDefinitionOverriding()) {
throw new BeanDefinitionOverrideException(beanName, beanDefinition, existingDefinition);
}
else if (existingDefinition.getRole() < beanDefinition.getRole()) {
// e.g. was ROLE_APPLICATION, now overriding with ROLE_SUPPORT or ROLE_INFRASTRUCTURE
if (logger.isInfoEnabled()) {
logger.info("Overriding user-defined bean definition for bean '" + beanName +
"' with a framework-generated bean definition: replacing [" +
existingDefinition + "] with [" + beanDefinition + "]");
}
}
else if (!beanDefinition.equals(existingDefinition)) {
if (logger.isDebugEnabled()) {
logger.debug("Overriding bean definition for bean '" + beanName +
"' with a different definition: replacing [" + existingDefinition +
"] with [" + beanDefinition + "]");
}
}
else {
if (logger.isTraceEnabled()) {
logger.trace("Overriding bean definition for bean '" + beanName +
"' with an equivalent definition: replacing [" + existingDefinition +
"] with [" + beanDefinition + "]");
}
}
this.beanDefinitionMap.put(beanName, beanDefinition);
}
else {
// 没有同名的bean存在时
if (hasBeanCreationStarted()) {
// Cannot modify startup-time collection elements anymore (for stable iteration)
synchronized (this.beanDefinitionMap) {
// beanDefinitionMap存储beanName:BeanDefinition一一对应的K:V信息
// beanName作为key， beanDefinition作为value存入DefaultListableBeanFactory对象的beanDefinitionMap字段中
// 完成Bean的注册，将Bean注册到BeanFactory中
this.beanDefinitionMap.put(beanName, beanDefinition);
List<String> updatedDefinitions = new ArrayList<>(this.beanDefinitionNames.size() + 1);
updatedDefinitions.addAll(this.beanDefinitionNames);
updatedDefinitions.add(beanName);
// 将所有的beanName保存到beanDefinitionNames字段中，数据类型为
this.beanDefinitionNames = updatedDefinitions;
removeManualSingletonName(beanName);
}
}
else {
// Still in startup registration phase
this.beanDefinitionMap.put(beanName, beanDefinition);
this.beanDefinitionNames.add(beanName);
removeManualSingletonName(beanName);
}
this.frozenBeanDefinitionNames = null;
}
if (existingDefinition != null || containsSingleton(beanName)) {
resetBeanDefinition(beanName);
}
}- 到此上面的 loadBeanDefinitions(XmlBeanDefinitionReader reader)方法基本执行完成
- 上一级的loadBeanDefinitions(DefaultListableBeanFactory beanFactory)方法也执行到loadBeanDefinitions(XmlBeanDefinitionReader reader)方法后结束
- 在上述创建BeanFactory的过程中，BeanDefination注册到BeanFactory（DefaultListableBeanFactory）中的类型为ConcurrentHashMap<String, BeanDefinition>，字段名beanDefinitionMap的为对象中
- 向beanDefinitionMap中注册时beanName为key,beanDefination为value；
- DefaultListableBeanFactory对象的字段beanDefinitionNames是一个ArrayList
类型数据，用于存储所有已经注册的Bean的名称 - refreshBeanFactory()方法执行完成，接下来进入其下一行的getBeanFactory()方法
getBeanFactory()方法的一种实现
- AbstractRefreshableApplicationContext中getBeanFactory()方法的一种实现
- 获取BeanFactory
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9@Override
public final ConfigurableListableBeanFactory getBeanFactory() {
synchronized (this.beanFactoryMonitor) {
if (this.beanFactory == null) {
throw new IllegalStateException("BeanFactory not initialized or already closed - call 'refresh' before accessing beans via the ApplicationContext");
}
return this.beanFactory;
}
} - getBeanFactory()方法执行完，标志上一级的方法obtainFreshBeanFactory()执行完成，接下来将进入AbstractApplicationContext抽象类中定义的refresh()模板方法中的第三步定义的prepareBeanFactory(beanFactory)方法
6 prepareBeanFactory(beanFactory)方法
- 代码位置: org.springframework.context.support.AbstractApplicationContext.java
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44protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
// Tell the internal bean factory to use the context's class loader etc.
beanFactory.setBeanClassLoader(getClassLoader());
beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));
// Configure the bean factory with context callbacks.
beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
beanFactory.ignoreDependencyInterface(EnvironmentAware.class);
beanFactory.ignoreDependencyInterface(EmbeddedValueResolverAware.class);
beanFactory.ignoreDependencyInterface(ResourceLoaderAware.class);
beanFactory.ignoreDependencyInterface(ApplicationEventPublisherAware.class);
beanFactory.ignoreDependencyInterface(MessageSourceAware.class);
beanFactory.ignoreDependencyInterface(ApplicationContextAware.class);
// BeanFactory interface not registered as resolvable type in a plain factory.
// MessageSource registered (and found for autowiring) as a bean.
beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory);
beanFactory.registerResolvableDependency(ResourceLoader.class, this);
beanFactory.registerResolvableDependency(ApplicationEventPublisher.class, this);
beanFactory.registerResolvableDependency(ApplicationContext.class, this);
// Register early post-processor for detecting inner beans as ApplicationListeners.
beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(this));
// Detect a LoadTimeWeaver and prepare for weaving, if found.
if (beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {
beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
// Set a temporary ClassLoader for type matching.
beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));
}
// Register default environment beans.
if (!beanFactory.containsLocalBean(ENVIRONMENT_BEAN_NAME)) {
beanFactory.registerSingleton(ENVIRONMENT_BEAN_NAME, getEnvironment());
}
if (!beanFactory.containsLocalBean(SYSTEM_PROPERTIES_BEAN_NAME)) {
beanFactory.registerSingleton(SYSTEM_PROPERTIES_BEAN_NAME, getEnvironment().getSystemProperties());
}
if (!beanFactory.containsLocalBean(SYSTEM_ENVIRONMENT_BEAN_NAME)) {
beanFactory.registerSingleton(SYSTEM_ENVIRONMENT_BEAN_NAME, getEnvironment().getSystemEnvironment());
}
}
7 postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory)
- 代码位置:org.springframework.context.support.AbstractApplicationContext.java
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5protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {
// 该方法是一个空方法，具体的实现依据具体的情况在其子类中继承或进行重写
// 观察AbstractApplicationContext到FileSystemXmlApplicationContext(location)的继承路径，其子类中并未实现具体的逻辑;
} - postProcessBeanFactory(beanFactory)执行完后进入 invokeBeanFactoryPostProcessors(beanFactory)方法
8. invokeBeanFactoryPostProcessors(beanFactory)方法
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- PostProcessorRegistrationDelegate的invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory, List
beanFactoryPostProcessors)静态方法 1
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153public static void invokeBeanFactoryPostProcessors(
ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {
// Invoke BeanDefinitionRegistryPostProcessors first, if any.
Set<String> processedBeans = new HashSet<>();
if (beanFactory instanceof BeanDefinitionRegistry) {
BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>();
List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();
for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
BeanDefinitionRegistryPostProcessor registryProcessor =
(BeanDefinitionRegistryPostProcessor) postProcessor;
registryProcessor.postProcessBeanDefinitionRegistry(registry);
registryProcessors.add(registryProcessor);
}
else {
regularPostProcessors.add(postProcessor);
}
}
// Do not initialize FactoryBeans here: We need to leave all regular beans
// uninitialized to let the bean factory post-processors apply to them!
// Separate between BeanDefinitionRegistryPostProcessors that implement
// PriorityOrdered, Ordered, and the rest.
List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();
// First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
String[] postProcessorNames =
beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
for (String ppName : postProcessorNames) {
if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
processedBeans.add(ppName);
}
}
sortPostProcessors(currentRegistryProcessors, beanFactory);
registryProcessors.addAll(currentRegistryProcessors);
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();
// Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
for (String ppName : postProcessorNames) {
if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) {
currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
processedBeans.add(ppName);
}
}
sortPostProcessors(currentRegistryProcessors, beanFactory);
registryProcessors.addAll(currentRegistryProcessors);
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();
// Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.
boolean reiterate = true;
while (reiterate) {
reiterate = false;
postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
for (String ppName : postProcessorNames) {
if (!processedBeans.contains(ppName)) {
currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
processedBeans.add(ppName);
reiterate = true;
}
}
sortPostProcessors(currentRegistryProcessors, beanFactory);
registryProcessors.addAll(currentRegistryProcessors);
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
currentRegistryProcessors.clear();
}
// Now, invoke the postProcessBeanFactory callback of all processors handled so far.
invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
}
else {
// Invoke factory processors registered with the context instance.
invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory);
}
// Do not initialize FactoryBeans here: We need to leave all regular beans
// uninitialized to let the bean factory post-processors apply to them!
String[] postProcessorNames =
beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);
// Separate between BeanFactoryPostProcessors that implement PriorityOrdered,
// Ordered, and the rest.
List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
List<String> orderedPostProcessorNames = new ArrayList<>();
List<String> nonOrderedPostProcessorNames = new ArrayList<>();
for (String ppName : postProcessorNames) {
if (processedBeans.contains(ppName)) {
// skip - already processed in first phase above
}
else if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
priorityOrderedPostProcessors.add(beanFactory.getBean(ppName, BeanFactoryPostProcessor.class));
}
else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
orderedPostProcessorNames.add(ppName);
}
else {
nonOrderedPostProcessorNames.add(ppName);
}
}
// First, invoke the BeanFactoryPostProcessors that implement PriorityOrdered.
sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);
// Next, invoke the BeanFactoryPostProcessors that implement Ordered.
List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<>(orderedPostProcessorNames.size());
for (String postProcessorName : orderedPostProcessorNames) {
orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
}
sortPostProcessors(orderedPostProcessors, beanFactory);
invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);
// Finally, invoke all other BeanFactoryPostProcessors.
List<BeanFactoryPostProcessor> nonOrderedPostProcessors = new ArrayList<>(nonOrderedPostProcessorNames.size());
for (String postProcessorName : nonOrderedPostProcessorNames) {
nonOrderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
}
invokeBeanFactoryPostProcessors(nonOrderedPostProcessors, beanFactory);
// Clear cached merged bean definitions since the post-processors might have
// modified the original metadata, e.g. replacing placeholders in values...
beanFactory.clearMetadataCache();
}
// 上面的方法内部有调用该重载方法
private static void invokeBeanDefinitionRegistryPostProcessors(
Collection<? extends BeanDefinitionRegistryPostProcessor> postProcessors, BeanDefinitionRegistry registry) {
for (BeanDefinitionRegistryPostProcessor postProcessor : postProcessors) {
postProcessor.postProcessBeanDefinitionRegistry(registry);
}
}
// 上面的方法内部有调用该方法
private static void sortPostProcessors(List<?> postProcessors, ConfigurableListableBeanFactory beanFactory) {
Comparator<Object> comparatorToUse = null;
if (beanFactory instanceof DefaultListableBeanFactory) {
comparatorToUse = ((DefaultListableBeanFactory) beanFactory).getDependencyComparator();
}
if (comparatorToUse == null) {
comparatorToUse = OrderComparator.INSTANCE;
}
postProcessors.sort(comparatorToUse);
}
9. registerBeanPostProcessors(beanFactory);方法
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- PostProcessorRegistrationDelegate的registerBeanPostProcessors(ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContexs)静态方法，具体代码如下：
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78public static void registerBeanPostProcessors(
ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) {
String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanPostProcessor.class, true, false);
// Register BeanPostProcessorChecker that logs an info message when
// a bean is created during BeanPostProcessor instantiation, i.e. when
// a bean is not eligible for getting processed by all BeanPostProcessors.
int beanProcessorTargetCount = beanFactory.getBeanPostProcessorCount() + 1 + postProcessorNames.length;
beanFactory.addBeanPostProcessor(new BeanPostProcessorChecker(beanFactory, beanProcessorTargetCount));
// Separate between BeanPostProcessors that implement PriorityOrdered,
// Ordered, and the rest.
List<BeanPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
List<BeanPostProcessor> internalPostProcessors = new ArrayList<>();
List<String> orderedPostProcessorNames = new ArrayList<>();
List<String> nonOrderedPostProcessorNames = new ArrayList<>();
for (String ppName : postProcessorNames) {
if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
priorityOrderedPostProcessors.add(pp);
if (pp instanceof MergedBeanDefinitionPostProcessor) {
internalPostProcessors.add(pp);
}
}
else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
orderedPostProcessorNames.add(ppName);
}
else {
nonOrderedPostProcessorNames.add(ppName);
}
}
// First, register the BeanPostProcessors that implement PriorityOrdered.
sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);
// Next, register the BeanPostProcessors that implement Ordered.
List<BeanPostProcessor> orderedPostProcessors = new ArrayList<>(orderedPostProcessorNames.size());
for (String ppName : orderedPostProcessorNames) {
BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
orderedPostProcessors.add(pp);
if (pp instanceof MergedBeanDefinitionPostProcessor) {
internalPostProcessors.add(pp);
}
}
sortPostProcessors(orderedPostProcessors, beanFactory);
registerBeanPostProcessors(beanFactory, orderedPostProcessors);
// Now, register all regular BeanPostProcessors.
List<BeanPostProcessor> nonOrderedPostProcessors = new ArrayList<>(nonOrderedPostProcessorNames.size());
for (String ppName : nonOrderedPostProcessorNames) {
BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
nonOrderedPostProcessors.add(pp);
if (pp instanceof MergedBeanDefinitionPostProcessor) {
internalPostProcessors.add(pp);
}
}
registerBeanPostProcessors(beanFactory, nonOrderedPostProcessors);
// Finally, re-register all internal BeanPostProcessors.
sortPostProcessors(internalPostProcessors, beanFactory);
registerBeanPostProcessors(beanFactory, internalPostProcessors);
// Re-register post-processor for detecting inner beans as ApplicationListeners,
// moving it to the end of the processor chain (for picking up proxies etc).
beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext));
}
//上面的方法内部有调用该重载方法
private static void registerBeanPostProcessors(
ConfigurableListableBeanFactory beanFactory, List<BeanPostProcessor> postProcessors) {
for (BeanPostProcessor postProcessor : postProcessors) {
beanFactory.addBeanPostProcessor(postProcessor);
}
}
10. initMessageSource();方法
- org.springframework.context.support.AbstractApplicationContext中的initMessageSource()方法
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28protected void initMessageSource() {
ConfigurableListableBeanFactory beanFactory = getBeanFactory();
if (beanFactory.containsLocalBean(MESSAGE_SOURCE_BEAN_NAME)) {
this.messageSource = beanFactory.getBean(MESSAGE_SOURCE_BEAN_NAME, MessageSource.class);
// Make MessageSource aware of parent MessageSource.
if (this.parent != null && this.messageSource instanceof HierarchicalMessageSource) {
HierarchicalMessageSource hms = (HierarchicalMessageSource) this.messageSource;
if (hms.getParentMessageSource() == null) {
// Only set parent context as parent MessageSource if no parent MessageSource
// registered already.
hms.setParentMessageSource(getInternalParentMessageSource());
}
}
if (logger.isTraceEnabled()) {
logger.trace("Using MessageSource [" + this.messageSource + "]");
}
}
else {
// Use empty MessageSource to be able to accept getMessage calls.
DelegatingMessageSource dms = new DelegatingMessageSource();
dms.setParentMessageSource(getInternalParentMessageSource());
this.messageSource = dms;
beanFactory.registerSingleton(MESSAGE_SOURCE_BEAN_NAME, this.messageSource);
if (logger.isTraceEnabled()) {
logger.trace("No '" + MESSAGE_SOURCE_BEAN_NAME + "' bean, using [" + this.messageSource + "]");
}
}
}
11. initApplicationEventMulticaster();方法
- org.springframework.context.support.AbstractApplicationContext中的initApplicationEventMulticaster()方法
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18protected void initApplicationEventMulticaster() {
ConfigurableListableBeanFactory beanFactory = getBeanFactory();
if (beanFactory.containsLocalBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME)) {
this.applicationEventMulticaster =
beanFactory.getBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, ApplicationEventMulticaster.class);
if (logger.isTraceEnabled()) {
logger.trace("Using ApplicationEventMulticaster [" + this.applicationEventMulticaster + "]");
}
}
else {
this.applicationEventMulticaster = new SimpleApplicationEventMulticaster(beanFactory);
beanFactory.registerSingleton(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, this.applicationEventMulticaster);
if (logger.isTraceEnabled()) {
logger.trace("No '" + APPLICATION_EVENT_MULTICASTER_BEAN_NAME + "' bean, using " +
"[" + this.applicationEventMulticaster.getClass().getSimpleName() + "]");
}
}
}
12. onRefresh();方法
- org.springframework.context.support.AbstractApplicationContext中的onRefresh()方法
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5protected void onRefresh() throws BeansException {
// 该方法是一个空方法，具体的实现依据具体的情况在其子类中继承或进行重写
// For subclasses: do nothing by default.
}
13. registerListeners();方法
- org.springframework.context.support.AbstractApplicationContext中的registerListeners()方法
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23protected void registerListeners() {
// Register statically specified listeners first.
for (ApplicationListener<?> listener : getApplicationListeners()) {
getApplicationEventMulticaster().addApplicationListener(listener);
}
// Do not initialize FactoryBeans here: We need to leave all regular beans
// uninitialized to let post-processors apply to them!
String[] listenerBeanNames = getBeanNamesForType(ApplicationListener.class, true, false);
for (String listenerBeanName : listenerBeanNames) {
getApplicationEventMulticaster().addApplicationListenerBean(listenerBeanName);
}
// Publish early application events now that we finally have a multicaster...
Set<ApplicationEvent> earlyEventsToProcess = this.earlyApplicationEvents;
this.earlyApplicationEvents = null;
if (earlyEventsToProcess != null) {
for (ApplicationEvent earlyEvent : earlyEventsToProcess) {
getApplicationEventMulticaster().multicastEvent(earlyEvent);
}
}
}
14. finishBeanFactoryInitialization(beanFactory);方法
- org.springframework.context.support.AbstractApplicationContext中的finishBeanFactoryInitialization(beanFactory)方法
- 实例化Bean的核心方法
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34protected void finishBeanFactoryInitialization(ConfigurableListableBeanFactory beanFactory) {
// Initialize conversion service for this context.
if (beanFactory.containsBean(CONVERSION_SERVICE_BEAN_NAME) &&
beanFactory.isTypeMatch(CONVERSION_SERVICE_BEAN_NAME, ConversionService.class)) {
beanFactory.setConversionService(
beanFactory.getBean(CONVERSION_SERVICE_BEAN_NAME, ConversionService.class));
}
// Register a default embedded value resolver if no bean post-processor
// (such as a PropertyPlaceholderConfigurer bean) registered any before:
// at this point, primarily for resolution in annotation attribute values.
if (!beanFactory.hasEmbeddedValueResolver()) {
beanFactory.addEmbeddedValueResolver(strVal -> getEnvironment().resolvePlaceholders(strVal));
}
// Initialize LoadTimeWeaverAware beans early to allow for registering their transformers early.
String[] weaverAwareNames = beanFactory.getBeanNamesForType(LoadTimeWeaverAware.class, false, false);
for (String weaverAwareName : weaverAwareNames) {
getBean(weaverAwareName);
}
// Stop using the temporary ClassLoader for type matching.
beanFactory.setTempClassLoader(null);
// Allow for caching all bean definition metadata, not expecting further changes.
beanFactory.freezeConfiguration();
// Instantiate all remaining (non-lazy-init) singletons.
// 实例化bean的核心代码
beanFactory.preInstantiateSingletons();
// 上一行的preInstantiateSingletons()方法定义在ConfigurableListableBeanFactory接口中，
// 具体实现是在DefaultListableBeanFactory中preInstantiateSingletons()方法
}
DefaultListableBeanFactory中preInstantiateSingletons()方法
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preInstantiateSingletons()方法中调用的getBean方法
- getBean方法定义在BeanFactory接口中
- getBean方法org.springframework.beans.factory.support.AbstractBeanFactory中实现
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175@Override
public Object getBean(String name) throws BeansException {
return doGetBean(name, null, null, false);
}
//下面是上面方法调用doGetBean(name, null, null, false)方法
// 这个方法特别长，以下是完整代码：
@SuppressWarnings("unchecked")
protected <T> T doGetBean(final String name, @Nullable final Class<T> requiredType,
@Nullable final Object[] args, boolean typeCheckOnly) throws BeansException {
final String beanName = transformedBeanName(name);
Object bean;
// Eagerly check singleton cache for manually registered singletons.
Object sharedInstance = getSingleton(beanName);
if (sharedInstance != null && args == null) {
if (logger.isTraceEnabled()) {
if (isSingletonCurrentlyInCreation(beanName)) {
logger.trace("Returning eagerly cached instance of singleton bean '" + beanName +
"' that is not fully initialized yet - a consequence of a circular reference");
}
else {
logger.trace("Returning cached instance of singleton bean '" + beanName + "'");
}
}
bean = getObjectForBeanInstance(sharedInstance, name, beanName, null);
}
else {
// Fail if we're already creating this bean instance:
// We're assumably within a circular reference.
if (isPrototypeCurrentlyInCreation(beanName)) {
throw new BeanCurrentlyInCreationException(beanName);
}
// Check if bean definition exists in this factory.
BeanFactory parentBeanFactory = getParentBeanFactory();
if (parentBeanFactory != null && !containsBeanDefinition(beanName)) {
// Not found -> check parent.
String nameToLookup = originalBeanName(name);
if (parentBeanFactory instanceof AbstractBeanFactory) {
return ((AbstractBeanFactory) parentBeanFactory).doGetBean(
nameToLookup, requiredType, args, typeCheckOnly);
}
else if (args != null) {
// Delegation to parent with explicit args.
return (T) parentBeanFactory.getBean(nameToLookup, args);
}
else if (requiredType != null) {
// No args -> delegate to standard getBean method.
return parentBeanFactory.getBean(nameToLookup, requiredType);
}
else {
return (T) parentBeanFactory.getBean(nameToLookup);
}
}
if (!typeCheckOnly) {
markBeanAsCreated(beanName);
}
try {
final RootBeanDefinition mbd = getMergedLocalBeanDefinition(beanName);
checkMergedBeanDefinition(mbd, beanName, args);
// Guarantee initialization of beans that the current bean depends on.
// 获取当前bean的依赖关系
String[] dependsOn = mbd.getDependsOn();
// 根据依赖的beanName递归调用getBean()方法，不断探寻其依赖的bean，直到getSingleton方法返回依赖的Bean，即当前正在创建的Bean
// 直到依赖关系最底层的bean没有依赖对象了，至此整个递归过程结束
if (dependsOn != null) {
for (String dep : dependsOn) {
if (isDependent(beanName, dep)) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName,
"Circular depends-on relationship between '" + beanName + "' and '" + dep + "'");
}
//
registerDependentBean(dep, beanName);
try {
getBean(dep);
}
catch (NoSuchBeanDefinitionException ex) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName,
"'" + beanName + "' depends on missing bean '" + dep + "'", ex);
}
}
}
// Create bean instance.
if (mbd.isSingleton()) {
// getSingleton方法的参数是createBean(beanName, mbd, args)方法的返回值
sharedInstance = getSingleton(beanName, () -> {
try {
// createBean方法在AbstractBeanFactory抽象类中定义，具体实现是在AbstractAutowireCapableBeanFactory抽象类中
return createBean(beanName, mbd, args);
}
catch (BeansException ex) {
// Explicitly remove instance from singleton cache: It might have been put there
// eagerly by the creation process, to allow for circular reference resolution.
// Also remove any beans that received a temporary reference to the bean.
destroySingleton(beanName);
throw ex;
}
});
bean = getObjectForBeanInstance(sharedInstance, name, beanName, mbd);
}
else if (mbd.isPrototype()) {
// It's a prototype -> create a new instance.
Object prototypeInstance = null;
try {
beforePrototypeCreation(beanName);
prototypeInstance = createBean(beanName, mbd, args);
}
finally {
afterPrototypeCreation(beanName);
}
bean = getObjectForBeanInstance(prototypeInstance, name, beanName, mbd);
}
else {
String scopeName = mbd.getScope();
final Scope scope = this.scopes.get(scopeName);
if (scope == null) {
throw new IllegalStateException("No Scope registered for scope name '" + scopeName + "'");
}
try {
Object scopedInstance = scope.get(beanName, () -> {
beforePrototypeCreation(beanName);
try {
return createBean(beanName, mbd, args);
}
finally {
afterPrototypeCreation(beanName);
}
});
bean = getObjectForBeanInstance(scopedInstance, name, beanName, mbd);
}
catch (IllegalStateException ex) {
throw new BeanCreationException(beanName,
"Scope '" + scopeName + "' is not active for the current thread; consider " +
"defining a scoped proxy for this bean if you intend to refer to it from a singleton",
ex);
}
}
}
catch (BeansException ex) {
cleanupAfterBeanCreationFailure(beanName);
throw ex;
}
}
// Check if required type matches the type of the actual bean instance.
if (requiredType != null && !requiredType.isInstance(bean)) {
try {
T convertedBean = getTypeConverter().convertIfNecessary(bean, requiredType);
if (convertedBean == null) {
throw new BeanNotOfRequiredTypeException(name, requiredType, bean.getClass());
}
return convertedBean;
}
catch (TypeMismatchException ex) {
if (logger.isTraceEnabled()) {
logger.trace("Failed to convert bean '" + name + "' to required type '" +
ClassUtils.getQualifiedName(requiredType) + "'", ex);
}
throw new BeanNotOfRequiredTypeException(name, requiredType, bean.getClass());
}
}
return (T) bean;
}
AbstractAutowireCapableBeanFactory类中的createBean(String beanName, RootBeanDefinition mbd, @Nullable Object[] args)方法
- 代码位置：org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory
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249@Override
protected Object createBean(String beanName, RootBeanDefinition mbd, @Nullable Object[] args)
throws BeanCreationException {
if (logger.isTraceEnabled()) {
logger.trace("Creating instance of bean '" + beanName + "'");
}
RootBeanDefinition mbdToUse = mbd;
// Make sure bean class is actually resolved at this point, and
// clone the bean definition in case of a dynamically resolved Class
// which cannot be stored in the shared merged bean definition.
Class<?> resolvedClass = resolveBeanClass(mbd, beanName);
if (resolvedClass != null && !mbd.hasBeanClass() && mbd.getBeanClassName() != null) {
mbdToUse = new RootBeanDefinition(mbd);
mbdToUse.setBeanClass(resolvedClass);
}
// Prepare method overrides.
try {
mbdToUse.prepareMethodOverrides();
}
catch (BeanDefinitionValidationException ex) {
throw new BeanDefinitionStoreException(mbdToUse.getResourceDescription(),
beanName, "Validation of method overrides failed", ex);
}
try {
// Give BeanPostProcessors a chance to return a proxy instead of the target bean instance.
Object bean = resolveBeforeInstantiation(beanName, mbdToUse);
if (bean != null) {
return bean;
}
}
catch (Throwable ex) {
throw new BeanCreationException(mbdToUse.getResourceDescription(), beanName,
"BeanPostProcessor before instantiation of bean failed", ex);
}
try {
// createBean方法的核心 该方法会返回Bean对象的实例，具体代码在下面贴出
Object beanInstance = doCreateBean(beanName, mbdToUse, args);
if (logger.isTraceEnabled()) {
logger.trace("Finished creating instance of bean '" + beanName + "'");
}
return beanInstance;
}
catch (BeanCreationException | ImplicitlyAppearedSingletonException ex) {
// A previously detected exception with proper bean creation context already,
// or illegal singleton state to be communicated up to DefaultSingletonBeanRegistry.
throw ex;
}
catch (Throwable ex) {
throw new BeanCreationException(
mbdToUse.getResourceDescription(), beanName, "Unexpected exception during bean creation", ex);
}
}
// 在AbstractAutowireCapableBeanFactory抽象类的createBean方法中调用的doCreateBean(beanName, mbdToUse, args)方法
protected Object doCreateBean(final String beanName, final RootBeanDefinition mbd, final @Nullable Object[] args)
throws BeanCreationException {
// Instantiate the bean.
BeanWrapper instanceWrapper = null;
if (mbd.isSingleton()) {
instanceWrapper = this.factoryBeanInstanceCache.remove(beanName);
}
if (instanceWrapper == null) {
// 创建Bean实例
instanceWrapper = createBeanInstance(beanName, mbd, args);
}
final Object bean = instanceWrapper.getWrappedInstance();
Class<?> beanType = instanceWrapper.getWrappedClass();
if (beanType != NullBean.class) {
mbd.resolvedTargetType = beanType;
}
// Allow post-processors to modify the merged bean definition.
synchronized (mbd.postProcessingLock) {
if (!mbd.postProcessed) {
try {
applyMergedBeanDefinitionPostProcessors(mbd, beanType, beanName);
}
catch (Throwable ex) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName,
"Post-processing of merged bean definition failed", ex);
}
mbd.postProcessed = true;
}
}
// Eagerly cache singletons to be able to resolve circular references
// even when triggered by lifecycle interfaces like BeanFactoryAware.
boolean earlySingletonExposure = (mbd.isSingleton() && this.allowCircularReferences &&
isSingletonCurrentlyInCreation(beanName));
if (earlySingletonExposure) {
if (logger.isTraceEnabled()) {
logger.trace("Eagerly caching bean '" + beanName +
"' to allow for resolving potential circular references");
}
addSingletonFactory(beanName, () -> getEarlyBeanReference(beanName, mbd, bean));
}
// Initialize the bean instance.
Object exposedObject = bean;
try {
// 填充bean，实际进行依赖注入的地方
populateBean(beanName, mbd, instanceWrapper);
exposedObject = initializeBean(beanName, exposedObject, mbd);
}
catch (Throwable ex) {
if (ex instanceof BeanCreationException && beanName.equals(((BeanCreationException) ex).getBeanName())) {
throw (BeanCreationException) ex;
}
else {
throw new BeanCreationException(
mbd.getResourceDescription(), beanName, "Initialization of bean failed", ex);
}
}
if (earlySingletonExposure) {
Object earlySingletonReference = getSingleton(beanName, false);
if (earlySingletonReference != null) {
if (exposedObject == bean) {
exposedObject = earlySingletonReference;
}
else if (!this.allowRawInjectionDespiteWrapping && hasDependentBean(beanName)) {
String[] dependentBeans = getDependentBeans(beanName);
Set<String> actualDependentBeans = new LinkedHashSet<>(dependentBeans.length);
for (String dependentBean : dependentBeans) {
if (!removeSingletonIfCreatedForTypeCheckOnly(dependentBean)) {
actualDependentBeans.add(dependentBean);
}
}
if (!actualDependentBeans.isEmpty()) {
throw new BeanCurrentlyInCreationException(beanName,
"Bean with name '" + beanName + "' has been injected into other beans [" +
StringUtils.collectionToCommaDelimitedString(actualDependentBeans) +
"] in its raw version as part of a circular reference, but has eventually been " +
"wrapped. This means that said other beans do not use the final version of the " +
"bean. This is often the result of over-eager type matching - consider using " +
"'getBeanNamesOfType' with the 'allowEagerInit' flag turned off, for example.");
}
}
}
}
// Register bean as disposable.
try {
registerDisposableBeanIfNecessary(beanName, bean, mbd);
}
catch (BeanDefinitionValidationException ex) {
throw new BeanCreationException(
mbd.getResourceDescription(), beanName, "Invalid destruction signature", ex);
}
return exposedObject;
}
// 在AbstractAutowireCapableBeanFactory抽象类的doCreateBean方法中调用的 createBeanInstance(beanName, mbd, args)方法
protected BeanWrapper createBeanInstance(String beanName, RootBeanDefinition mbd, @Nullable Object[] args) {
// Make sure bean class is actually resolved at this point.
Class<?> beanClass = resolveBeanClass(mbd, beanName);
if (beanClass != null && !Modifier.isPublic(beanClass.getModifiers()) && !mbd.isNonPublicAccessAllowed()) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName,
"Bean class isn't public, and non-public access not allowed: " + beanClass.getName());
}
Supplier<?> instanceSupplier = mbd.getInstanceSupplier();
if (instanceSupplier != null) {
return obtainFromSupplier(instanceSupplier, beanName);
}
if (mbd.getFactoryMethodName() != null) {
return instantiateUsingFactoryMethod(beanName, mbd, args);
}
// Shortcut when re-creating the same bean...
boolean resolved = false;
boolean autowireNecessary = false;
if (args == null) {
synchronized (mbd.constructorArgumentLock) {
if (mbd.resolvedConstructorOrFactoryMethod != null) {
resolved = true;
autowireNecessary = mbd.constructorArgumentsResolved;
}
}
}
if (resolved) {
if (autowireNecessary) {
return autowireConstructor(beanName, mbd, null, null);
}
else {
// 调用instantiateBean方法
return instantiateBean(beanName, mbd);
}
}
// Candidate constructors for autowiring?
Constructor<?>[] ctors = determineConstructorsFromBeanPostProcessors(beanClass, beanName);
if (ctors != null || mbd.getResolvedAutowireMode() == AUTOWIRE_CONSTRUCTOR ||
mbd.hasConstructorArgumentValues() || !ObjectUtils.isEmpty(args)) {
return autowireConstructor(beanName, mbd, ctors, args);
}
// Preferred constructors for default construction?
ctors = mbd.getPreferredConstructors();
if (ctors != null) {
return autowireConstructor(beanName, mbd, ctors, null);
}
// No special handling: simply use no-arg constructor.
return instantiateBean(beanName, mbd);
}
// 在AbstractAutowireCapableBeanFactory抽象类的createBeanInstance方法中调用的instantiateBean(beanName, mbd)方法
protected BeanWrapper instantiateBean(final String beanName, final RootBeanDefinition mbd) {
try {
Object beanInstance;
final BeanFactory parent = this;
if (System.getSecurityManager() != null) {
// 核心逻辑
beanInstance = AccessController.doPrivileged((PrivilegedAction<Object>) () ->
getInstantiationStrategy().instantiate(mbd, beanName, parent),
getAccessControlContext());
}
else {
// 核心逻辑
beanInstance = getInstantiationStrategy().instantiate(mbd, beanName, parent);
}
BeanWrapper bw = new BeanWrapperImpl(beanInstance);
initBeanWrapper(bw);
return bw;
}
catch (Throwable ex) {
throw new BeanCreationException(
mbd.getResourceDescription(), beanName, "Instantiation of bean failed", ex);
}
}
// 上面的getInstantiationStrategy()方法代码
protected InstantiationStrategy getInstantiationStrategy() {
return this.instantiationStrategy;
}
getInstantiationStrategy()方法的返回接口对象的策略对象的一个实现SimpleInstantiationStrategy
- org.springframework.beans.factory.support.SimpleInstantiationStrategy
- SimpleInstantiationStrategy.instantiate(RootBeanDefinition bd, @Nullable String beanName, BeanFactory owner)方法的具体实现：
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35@Override
public Object instantiate(RootBeanDefinition bd, @Nullable String beanName, BeanFactory owner) {
// Don't override the class with CGLIB if no overrides.
if (!bd.hasMethodOverrides()) {
Constructor<?> constructorToUse;
synchronized (bd.constructorArgumentLock) {
constructorToUse = (Constructor<?>) bd.resolvedConstructorOrFactoryMethod;
if (constructorToUse == null) {
final Class<?> clazz = bd.getBeanClass();
if (clazz.isInterface()) {
throw new BeanInstantiationException(clazz, "Specified class is an interface");
}
try {
if (System.getSecurityManager() != null) {
constructorToUse = AccessController.doPrivileged(
(PrivilegedExceptionAction<Constructor<?>>) clazz::getDeclaredConstructor);
}
else {
constructorToUse = clazz.getDeclaredConstructor();
}
bd.resolvedConstructorOrFactoryMethod = constructorToUse;
}
catch (Throwable ex) {
throw new BeanInstantiationException(clazz, "No default constructor found", ex);
}
}
}
// 调用静态方法BeanUtils.instantiateClass(constructorToUse);
return BeanUtils.instantiateClass(constructorToUse);
}
else {
// Must generate CGLIB subclass.
return instantiateWithMethodInjection(bd, beanName, owner);
}
}静态方法BeanUtils.instantiateClass(constructorToUse)的实现细节
- 代码位置：org.springframework.beans.BeanUtils
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42public static <T> T instantiateClass(Constructor<T> ctor, Object... args) throws BeanInstantiationException {
Assert.notNull(ctor, "Constructor must not be null");
try {
ReflectionUtils.makeAccessible(ctor);
// 判断是否是Kotlin类型
if (KotlinDetector.isKotlinReflectPresent() && KotlinDetector.isKotlinType(ctor.getDeclaringClass())) {
// 是Kotlin类型
return KotlinDelegate.instantiateClass(ctor, args);
}
else {
// 不是Kotlin类型
Class<?>[] parameterTypes = ctor.getParameterTypes();
Assert.isTrue(args.length <= parameterTypes.length, "Can't specify more arguments than constructor parameters");
Object[] argsWithDefaultValues = new Object[args.length];
for (int i = 0 ; i < args.length; i++) {
if (args[i] == null) {
Class<?> parameterType = parameterTypes[i];
argsWithDefaultValues[i] = (parameterType.isPrimitive() ? DEFAULT_TYPE_VALUES.get(parameterType) : null);
}
else {
argsWithDefaultValues[i] = args[i];
}
}
// 调用Constructor的newInstance方法，使用反射创建实例
// 到此之后bean实例创建完成
return ctor.newInstance(argsWithDefaultValues);
}
}
catch (InstantiationException ex) {
throw new BeanInstantiationException(ctor, "Is it an abstract class?", ex);
}
catch (IllegalAccessException ex) {
throw new BeanInstantiationException(ctor, "Is the constructor accessible?", ex);
}
catch (IllegalArgumentException ex) {
throw new BeanInstantiationException(ctor, "Illegal arguments for constructor", ex);
}
catch (InvocationTargetException ex) {
throw new BeanInstantiationException(ctor, "Constructor threw exception", ex.getTargetException());
}
}
AbstractAutowireCapableBeanFactory抽象类的中doCreateBean方法中调用的populateBean(beanName, mbd, instanceWrapper)方法
- 在AbstractAutowireCapableBeanFactory抽象类中的方法populateBean方法
- 该方法用于填充bean 具体发生依赖注入的地方####################################################################################################################################################33
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187@SuppressWarnings("deprecation") // for postProcessPropertyValues
protected void populateBean(String beanName, RootBeanDefinition mbd, @Nullable BeanWrapper bw) {
if (bw == null) {
if (mbd.hasPropertyValues()) {
throw new BeanCreationException(
mbd.getResourceDescription(), beanName, "Cannot apply property values to null instance");
}
else {
// Skip property population phase for null instance.
return;
}
}
// Give any InstantiationAwareBeanPostProcessors the opportunity to modify the
// state of the bean before properties are set. This can be used, for example,
// to support styles of field injection.
boolean continueWithPropertyPopulation = true;
if (!mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) {
for (BeanPostProcessor bp : getBeanPostProcessors()) {
if (bp instanceof InstantiationAwareBeanPostProcessor) {
InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;
if (!ibp.postProcessAfterInstantiation(bw.getWrappedInstance(), beanName)) {
continueWithPropertyPopulation = false;
break;
}
}
}
}
if (!continueWithPropertyPopulation) {
return;
}
// 获取bean的所有属性 用于后面配置Property元素 即依赖关系
PropertyValues pvs = (mbd.hasPropertyValues() ? mbd.getPropertyValues() : null);
int resolvedAutowireMode = mbd.getResolvedAutowireMode();
if (resolvedAutowireMode == AUTOWIRE_BY_NAME || resolvedAutowireMode == AUTOWIRE_BY_TYPE) {
MutablePropertyValues newPvs = new MutablePropertyValues(pvs);
// Add property values based on autowire by name if applicable.
if (resolvedAutowireMode == AUTOWIRE_BY_NAME) {
autowireByName(beanName, mbd, bw, newPvs);
}
// Add property values based on autowire by type if applicable.
if (resolvedAutowireMode == AUTOWIRE_BY_TYPE) {
autowireByType(beanName, mbd, bw, newPvs);
}
pvs = newPvs;
}
boolean hasInstAwareBpps = hasInstantiationAwareBeanPostProcessors();
boolean needsDepCheck = (mbd.getDependencyCheck() != AbstractBeanDefinition.DEPENDENCY_CHECK_NONE);
PropertyDescriptor[] filteredPds = null;
if (hasInstAwareBpps) {
if (pvs == null) {
pvs = mbd.getPropertyValues();
}
for (BeanPostProcessor bp : getBeanPostProcessors()) {
if (bp instanceof InstantiationAwareBeanPostProcessor) {
InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;
PropertyValues pvsToUse = ibp.postProcessProperties(pvs, bw.getWrappedInstance(), beanName);
if (pvsToUse == null) {
if (filteredPds == null) {
filteredPds = filterPropertyDescriptorsForDependencyCheck(bw, mbd.allowCaching);
}
pvsToUse = ibp.postProcessPropertyValues(pvs, filteredPds, bw.getWrappedInstance(), beanName);
if (pvsToUse == null) {
return;
}
}
pvs = pvsToUse;
}
}
}
if (needsDepCheck) {
if (filteredPds == null) {
filteredPds = filterPropertyDescriptorsForDependencyCheck(bw, mbd.allowCaching);
}
checkDependencies(beanName, mbd, filteredPds, pvs);
}
if (pvs != null) {
// 核心逻辑 applyPropertyValues方法的具体代码在下面
applyPropertyValues(beanName, mbd, bw, pvs);
}
}
// 上面方法中调用的applyPropertyValues方法具体代码
protected void applyPropertyValues(String beanName, BeanDefinition mbd, BeanWrapper bw, PropertyValues pvs) {
if (pvs.isEmpty()) {
return;
}
if (System.getSecurityManager() != null && bw instanceof BeanWrapperImpl) {
((BeanWrapperImpl) bw).setSecurityContext(getAccessControlContext());
}
MutablePropertyValues mpvs = null;
List<PropertyValue> original;
if (pvs instanceof MutablePropertyValues) {
mpvs = (MutablePropertyValues) pvs;
if (mpvs.isConverted()) {
// Shortcut: use the pre-converted values as-is.
try {
bw.setPropertyValues(mpvs);
return;
}
catch (BeansException ex) {
throw new BeanCreationException(
mbd.getResourceDescription(), beanName, "Error setting property values", ex);
}
}
original = mpvs.getPropertyValueList();
}
else {
original = Arrays.asList(pvs.getPropertyValues());
}
TypeConverter converter = getCustomTypeConverter();
if (converter == null) {
converter = bw;
}
BeanDefinitionValueResolver valueResolver = new BeanDefinitionValueResolver(this, beanName, mbd, converter);
// Create a deep copy, resolving any references for values.
List<PropertyValue> deepCopy = new ArrayList<>(original.size());
boolean resolveNecessary = false;
for (PropertyValue pv : original) {
if (pv.isConverted()) {
deepCopy.add(pv);
}
else {
String propertyName = pv.getName();
Object originalValue = pv.getValue();
if (originalValue == AutowiredPropertyMarker.INSTANCE) {
Method writeMethod = bw.getPropertyDescriptor(propertyName).getWriteMethod();
if (writeMethod == null) {
throw new IllegalArgumentException("Autowire marker for property without write method: " + pv);
}
originalValue = new DependencyDescriptor(new MethodParameter(writeMethod, 0), true);
}
// 获取property对应的值 resolveValueIfNecessary方法的代码在下面给出
Object resolvedValue = valueResolver.resolveValueIfNecessary(pv, originalValue);
Object convertedValue = resolvedValue;
boolean convertible = bw.isWritableProperty(propertyName) &&
!PropertyAccessorUtils.isNestedOrIndexedProperty(propertyName);
if (convertible) {
convertedValue = convertForProperty(resolvedValue, propertyName, bw, converter);
}
// Possibly store converted value in merged bean definition,
// in order to avoid re-conversion for every created bean instance.
if (resolvedValue == originalValue) {
if (convertible) {
pv.setConvertedValue(convertedValue);
}
deepCopy.add(pv);
}
else if (convertible && originalValue instanceof TypedStringValue &&
!((TypedStringValue) originalValue).isDynamic() &&
!(convertedValue instanceof Collection || ObjectUtils.isArray(convertedValue))) {
pv.setConvertedValue(convertedValue);
deepCopy.add(pv);
}
else {
resolveNecessary = true;
deepCopy.add(new PropertyValue(pv, convertedValue));
}
}
}
if (mpvs != null && !resolveNecessary) {
mpvs.setConverted();
}
// Set our (possibly massaged) deep copy.
try {
// 获取到依赖的对象值后 将依赖值注入
bw.setPropertyValues(new MutablePropertyValues(deepCopy));
}
catch (BeansException ex) {
throw new BeanCreationException(
mbd.getResourceDescription(), beanName, "Error setting property values", ex);
}
}
valueResolver.resolveValueIfNecessary(pv, originalValue);对应的方法
- 代码位置：org.springframework.beans.factory.support.BeanDefinitionValueResolver
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173@Nullable
public Object resolveValueIfNecessary(Object argName, @Nullable Object value) {
// We must check each value to see whether it requires a runtime reference
// to another bean to be resolved.
if (value instanceof RuntimeBeanReference) {
RuntimeBeanReference ref = (RuntimeBeanReference) value;
// 核心逻辑 解决Bean依赖关系 具体代码在下方贴出
return resolveReference(argName, ref);
}
else if (value instanceof RuntimeBeanNameReference) {
String refName = ((RuntimeBeanNameReference) value).getBeanName();
refName = String.valueOf(doEvaluate(refName));
if (!this.beanFactory.containsBean(refName)) {
throw new BeanDefinitionStoreException(
"Invalid bean name '" + refName + "' in bean reference for " + argName);
}
return refName;
}
else if (value instanceof BeanDefinitionHolder) {
// Resolve BeanDefinitionHolder: contains BeanDefinition with name and aliases.
BeanDefinitionHolder bdHolder = (BeanDefinitionHolder) value;
return resolveInnerBean(argName, bdHolder.getBeanName(), bdHolder.getBeanDefinition());
}
else if (value instanceof BeanDefinition) {
// Resolve plain BeanDefinition, without contained name: use dummy name.
BeanDefinition bd = (BeanDefinition) value;
String innerBeanName = "(inner bean)" + BeanFactoryUtils.GENERATED_BEAN_NAME_SEPARATOR +
ObjectUtils.getIdentityHexString(bd);
return resolveInnerBean(argName, innerBeanName, bd);
}
else if (value instanceof DependencyDescriptor) {
Set<String> autowiredBeanNames = new LinkedHashSet<>(4);
Object result = this.beanFactory.resolveDependency(
(DependencyDescriptor) value, this.beanName, autowiredBeanNames, this.typeConverter);
for (String autowiredBeanName : autowiredBeanNames) {
if (this.beanFactory.containsBean(autowiredBeanName)) {
this.beanFactory.registerDependentBean(autowiredBeanName, this.beanName);
}
}
return result;
}
else if (value instanceof ManagedArray) {
// May need to resolve contained runtime references.
ManagedArray array = (ManagedArray) value;
Class<?> elementType = array.resolvedElementType;
if (elementType == null) {
String elementTypeName = array.getElementTypeName();
if (StringUtils.hasText(elementTypeName)) {
try {
elementType = ClassUtils.forName(elementTypeName, this.beanFactory.getBeanClassLoader());
array.resolvedElementType = elementType;
}
catch (Throwable ex) {
// Improve the message by showing the context.
throw new BeanCreationException(
this.beanDefinition.getResourceDescription(), this.beanName,
"Error resolving array type for " + argName, ex);
}
}
else {
elementType = Object.class;
}
}
return resolveManagedArray(argName, (List<?>) value, elementType);
}
else if (value instanceof ManagedList) {
// May need to resolve contained runtime references.
return resolveManagedList(argName, (List<?>) value);
}
else if (value instanceof ManagedSet) {
// May need to resolve contained runtime references.
return resolveManagedSet(argName, (Set<?>) value);
}
else if (value instanceof ManagedMap) {
// May need to resolve contained runtime references.
return resolveManagedMap(argName, (Map<?, ?>) value);
}
else if (value instanceof ManagedProperties) {
Properties original = (Properties) value;
Properties copy = new Properties();
original.forEach((propKey, propValue) -> {
if (propKey instanceof TypedStringValue) {
propKey = evaluate((TypedStringValue) propKey);
}
if (propValue instanceof TypedStringValue) {
propValue = evaluate((TypedStringValue) propValue);
}
if (propKey == null || propValue == null) {
throw new BeanCreationException(
this.beanDefinition.getResourceDescription(), this.beanName,
"Error converting Properties key/value pair for " + argName + ": resolved to null");
}
copy.put(propKey, propValue);
});
return copy;
}
else if (value instanceof TypedStringValue) {
// Convert value to target type here.
TypedStringValue typedStringValue = (TypedStringValue) value;
Object valueObject = evaluate(typedStringValue);
try {
Class<?> resolvedTargetType = resolveTargetType(typedStringValue);
if (resolvedTargetType != null) {
return this.typeConverter.convertIfNecessary(valueObject, resolvedTargetType);
}
else {
return valueObject;
}
}
catch (Throwable ex) {
// Improve the message by showing the context.
throw new BeanCreationException(
this.beanDefinition.getResourceDescription(), this.beanName,
"Error converting typed String value for " + argName, ex);
}
}
else if (value instanceof NullBean) {
return null;
}
else {
return evaluate(value);
}
}
// 上面resolveValueIfNecessary方法中调用的resolveReference方法
// 最后获取到依赖的bean
@Nullable
private Object resolveReference(Object argName, RuntimeBeanReference ref) {
try {
Object bean;
Class<?> beanType = ref.getBeanType();
if (ref.isToParent()) {
BeanFactory parent = this.beanFactory.getParentBeanFactory();
if (parent == null) {
throw new BeanCreationException(
this.beanDefinition.getResourceDescription(), this.beanName,
"Cannot resolve reference to bean " + ref +
" in parent factory: no parent factory available");
}
if (beanType != null) {
// 发生递归调用
bean = parent.getBean(beanType);
}
else {
// 发生递归调用 根据依赖的名称从BeanFactory中递归得到依赖 最后获取到依赖的bean
bean = parent.getBean(String.valueOf(doEvaluate(ref.getBeanName())));
}
}
else {
String resolvedName;
if (beanType != null) {
NamedBeanHolder<?> namedBean = this.beanFactory.resolveNamedBean(beanType);
bean = namedBean.getBeanInstance();
resolvedName = namedBean.getBeanName();
}
else {
resolvedName = String.valueOf(doEvaluate(ref.getBeanName()));
bean = this.beanFactory.getBean(resolvedName);
}
this.beanFactory.registerDependentBean(resolvedName, this.beanName);
}
if (bean instanceof NullBean) {
bean = null;
}
return bean;
}
catch (BeansException ex) {
throw new BeanCreationException(
this.beanDefinition.getResourceDescription(), this.beanName,
"Cannot resolve reference to bean '" + ref.getBeanName() + "' while setting " + argName, ex);
}
}
AbstractPropertyAccessor的setPropertyValues(PropertyValues pvs)方法
- 代码位置：org.springframework.beans.AbstractPropertyAccessor
- 循环属性列表
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48@Override
public void setPropertyValues(PropertyValues pvs) throws BeansException {
setPropertyValues(pvs, false, false);
}
// 循环属性列表
@Override
public void setPropertyValues(PropertyValues pvs, boolean ignoreUnknown, boolean ignoreInvalid)
throws BeansException {
List<PropertyAccessException> propertyAccessExceptions = null;
List<PropertyValue> propertyValues = (pvs instanceof MutablePropertyValues ?
((MutablePropertyValues) pvs).getPropertyValueList() : Arrays.asList(pvs.getPropertyValues()));
// 循环属性列表
for (PropertyValue pv : propertyValues) {
try {
// This method may throw any BeansException, which won't be caught
// here, if there is a critical failure such as no matching field.
// We can attempt to deal only with less serious exceptions.
// 该方法通过AbstractNestablePropertyAccessor的setPropertyValue(PropertyValue pv)方法实现
setPropertyValue(pv);
}
catch (NotWritablePropertyException ex) {
if (!ignoreUnknown) {
throw ex;
}
// Otherwise, just ignore it and continue...
}
catch (NullValueInNestedPathException ex) {
if (!ignoreInvalid) {
throw ex;
}
// Otherwise, just ignore it and continue...
}
catch (PropertyAccessException ex) {
if (propertyAccessExceptions == null) {
propertyAccessExceptions = new ArrayList<>();
}
propertyAccessExceptions.add(ex);
}
}
// If we encountered individual exceptions, throw the composite exception.
if (propertyAccessExceptions != null) {
PropertyAccessException[] paeArray = propertyAccessExceptions.toArray(new PropertyAccessException[0]);
throw new PropertyBatchUpdateException(paeArray);
}
}
AbstractNestablePropertyAccessor的 setPropertyValue(PropertyValue pv)方法
- 代码位置：org.springframework.beans.AbstractNestablePropertyAccessor########################################################################################################################################
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23@Override
public void setPropertyValue(PropertyValue pv) throws BeansException {
PropertyTokenHolder tokens = (PropertyTokenHolder) pv.resolvedTokens;
if (tokens == null) {
String propertyName = pv.getName();
AbstractNestablePropertyAccessor nestedPa;
try {
nestedPa = getPropertyAccessorForPropertyPath(propertyName);
}
catch (NotReadablePropertyException ex) {
throw new NotWritablePropertyException(getRootClass(), this.nestedPath + propertyName,
"Nested property in path '" + propertyName + "' does not exist", ex);
}
tokens = getPropertyNameTokens(getFinalPath(nestedPa, propertyName));
if (nestedPa == this) {
pv.getOriginalPropertyValue().resolvedTokens = tokens;
}
nestedPa.setPropertyValue(tokens, pv);
}
else {
setPropertyValue(tokens, pv);
}
} - 上面setPropertyValue(PropertyValue pv)方法的重载方法setPropertyValue(PropertyTokenHolder tokens, PropertyValue pv)
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8protected void setPropertyValue(PropertyTokenHolder tokens, PropertyValue pv) throws BeansException {
if (tokens.keys != null) {
processKeyedProperty(tokens, pv);
}
else {
processLocalProperty(tokens, pv);
}
} - processLocalProperty(PropertyTokenHolder tokens, PropertyValue pv)方法
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69private void processLocalProperty(PropertyTokenHolder tokens, PropertyValue pv) {
PropertyHandler ph = getLocalPropertyHandler(tokens.actualName);
if (ph == null || !ph.isWritable()) {
if (pv.isOptional()) {
if (logger.isDebugEnabled()) {
logger.debug("Ignoring optional value for property '" + tokens.actualName +
"' - property not found on bean class [" + getRootClass().getName() + "]");
}
return;
}
else {
throw createNotWritablePropertyException(tokens.canonicalName);
}
}
Object oldValue = null;
try {
Object originalValue = pv.getValue();//
Object valueToApply = originalValue;//
if (!Boolean.FALSE.equals(pv.conversionNecessary)) {
if (pv.isConverted()) {
valueToApply = pv.getConvertedValue();
}
else {
if (isExtractOldValueForEditor() && ph.isReadable()) {
try {
oldValue = ph.getValue();
}
catch (Exception ex) {
if (ex instanceof PrivilegedActionException) {
ex = ((PrivilegedActionException) ex).getException();
}
if (logger.isDebugEnabled()) {
logger.debug("Could not read previous value of property '" +
this.nestedPath + tokens.canonicalName + "'", ex);
}
}
}
valueToApply = convertForProperty(
tokens.canonicalName, oldValue, originalValue, ph.toTypeDescriptor());
}
pv.getOriginalPropertyValue().conversionNecessary = (valueToApply != originalValue);
}
ph.setValue(valueToApply);// 具体代码在下方列出
}
catch (TypeMismatchException ex) {
throw ex;
}
catch (InvocationTargetException ex) {
PropertyChangeEvent propertyChangeEvent = new PropertyChangeEvent(
getRootInstance(), this.nestedPath + tokens.canonicalName, oldValue, pv.getValue());
if (ex.getTargetException() instanceof ClassCastException) {
throw new TypeMismatchException(propertyChangeEvent, ph.getPropertyType(), ex.getTargetException());
}
else {
Throwable cause = ex.getTargetException();
if (cause instanceof UndeclaredThrowableException) {
// May happen e.g. with Groovy-generated methods
cause = cause.getCause();
}
throw new MethodInvocationException(propertyChangeEvent, cause);
}
}
catch (Exception ex) {
PropertyChangeEvent pce = new PropertyChangeEvent(
getRootInstance(), this.nestedPath + tokens.canonicalName, oldValue, pv.getValue());
throw new MethodInvocationException(pce, ex);
}
}
- 上述ph.setValue方法在org.springframework.beans.AbstractNestablePropertyAccessor抽象类中定义
- public abstract void setValue(@Nullable Object value) throws Exception;
- 一个具体实现在org.springframework.beans.BeanWrapperImp的内部类BeanPropertyHandler中，完整代码如下：
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26private final PropertyDescriptor pd; //BeanPropertyHandler中的字段
@Override
public void setValue(final @Nullable Object value) throws Exception {
final Method writeMethod = (this.pd instanceof GenericTypeAwarePropertyDescriptor ?
((GenericTypeAwarePropertyDescriptor) this.pd).getWriteMethodForActualAccess() :
this.pd.getWriteMethod());// 找到属性的set方法
if (System.getSecurityManager() != null) {
AccessController.doPrivileged((PrivilegedAction<Object>) () -> {
ReflectionUtils.makeAccessible(writeMethod);
return null;
});
try {
AccessController.doPrivileged((PrivilegedExceptionAction<Object>) () ->
writeMethod.invoke(getWrappedInstance(), value), acc);
// 调用Method的invoke方法，完成属性注入
}
catch (PrivilegedActionException ex) {
throw ex.getException();
}
}
else {
ReflectionUtils.makeAccessible(writeMethod);
writeMethod.invoke(getWrappedInstance(), value);//调用Method的invoke方法，完成属性注入
}
} - 至此Ioc容器的启动过程基本结束
15. finishRefresh();方法
- org.springframework.context.support.AbstractApplicationContext中的finishRefresh()方法
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16refresh()过程抛出异常时
- 之中有两个处理方法destroyBeans()和cancelRefresh(ex)
16.1 destroyBeans();方法
- org.springframework.context.support.AbstractApplicationContext中的destroyBeans()方法
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16.2 cancelRefresh(ex);方法
- org.springframework.context.support.AbstractApplicationContext中的cancelRefresh(ex)方法
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3protected void cancelRefresh(BeansException ex) {
this.active.set(false);
}16.3抛出异常BeansException
17 resetCommonCaches();方法
- org.springframework.context.support.AbstractApplicationContext中的resetCommonCaches()方法
- try-catch-finally代码块中finally包裹的方法
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ReflectionUtils.clearCache();
AnnotationUtils.clearCache();
ResolvableType.clearCache();
CachedIntrospectionResults.clearClassLoader(getClassLoader());
} - 执行到此Ioc容器启动完成，可以正式投入使用
总结
- Ioc的底层原理实现：Spring Ioc启动分为两步：
- 1.创建BeanFactory
- 2.实例化Bean
- Spring的Bean在内存中的状态就是BeanDefination
- 在Bean的创建和依赖注入的过程中，需要根据BeanDefination的信息来递归的完成依赖注入，从代码可以看到，这些递归都是以getBean()为入口的，一个递归是在上下文体系中查找需要的bean和bean的依赖关系；另一个递归是在依赖注入时，通过递归调用容器的getBean方法得到当前依赖的Bean，同时也触发对依赖bean的创建和注入。在对bean的属性进行依赖注入时，解析过程也是一个递归过程，这样根据依赖关系，一层一层的完成Bean的创建和注入，直到当前bean相关的整个依赖链的注入完成。由于整个IoC容器启动过程较为复杂，使用下面的一张图来描述让读者更清楚厘清IoC容器的启动过程。
模板
代码位置:org.springframework.context.support.AbstractApplicationContext.java
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3protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {
}代码位置:org.springframework.context.support.AbstractApplicationContext.java
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代码位置:.java
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代码位置:.java
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参考资料
- Spring源码深度解析（第二版） 郝佳
- Spring5企业级开发实战 周冠亚 黄文毅 配套源码
- Gitee同步版本：https://gitee.com/ACANX/spring5projectdemo
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