本篇文章为你整理了spring源码学习（读懂spring源码）的详细内容，包含有spring源码视频教程 读懂spring源码 spring源码深度解析(第2版) spring源码分析和总结简书 spring源码学习，希望能帮助你了解 spring源码学习。
spring架构
按照图中的流程，一定要自己使用idea工具配合着debug，慢慢去看里面源码，除了花费一点时间，不会很难，绝对可以理解的
spring测试用例：
maven依赖：
dependencies
dependency
groupId org.projectlombok /groupId
artifactId lombok /artifactId
version 1.18.0 /version
/dependency
dependency
groupId org.springframework /groupId
artifactId spring-context /artifactId
version 5.2.12.RELEASE /version
/dependency
/dependencies
测试类：
import lombok.Data;
@Data
public class Person {
private int id;
private String name;
private int age;
private String gender;
application.xml配置文件：
?xml version="1.0" encoding="UTF-8"?
beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"
!--注册一个对象，spring回自动创建这个对象--
一个bean标签就表示一个对象
id:这个对象的唯一标识
class:注册对象的完全限定名
bean id="person"
!--使用property标签给对象的属性赋值
name:表示属性的名称
value：表示属性的值
property name="id" value="1" /property
property name="name" value="zhangsan" /property
property name="age" value="18" /property
property name="gender" value="男" /property
/bean
/beans
启动类：
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class SpringDemoTest {
public static void main(String[] args) {
//ApplicationContext:表示spring容器
//ClassPathXmlApplicationContext:表示从当前classpath路径中获取xml文件的配置
//根据spring的配置文件来获取ioc容器对象
ApplicationContext context = new ClassPathXmlApplicationContext("application.xml");
Person person = context.getBean("person", Person.class);
System.out.println(person);
先允许确保正常打印person对象无误，打上断点，进行调式，deg代码
使用F7进入代码内部，这里处理了一个WebLogic 8.1应用关闭的bug，在AbstractApplicationContext类中
继续F7往下走，又回来了
继续F7进去往下走，调用了ClassPathXmlApplicationContext的构造方法
继续F7进去往下走，在构造方法中做了一些事情
这里调用了父类的构造方法，获取到了资源处理器
获取到了配置文件application.xml，使用setConfigLocations()放到了ConfigLocations，所以后面肯定会用到
然后调用了refresh();方法，
F7进入查看这个方法，里面一共调用了13个方法
@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.
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.
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 Springs core, since we
// might not ever need metadata for singleton beans anymore...
resetCommonCaches();
1、prepareRefresh();
refresh()方法刚进来时候，首先有个同步操作，开启和关闭不能同事进行，然后调用了prepareRefresh();方法
使用F7进去查看prepareRefresh()方法，有些有些注释是我手动加的说明
protected void prepareRefresh() {
// Switch to active.
this.startupDate = System.currentTimeMillis(); // 设置开始时间
this.closed.set(false); // 设置ioc容器的状态，closed是关闭的
this.active.set(true); // active 是true的
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(); // 初始化子类扩展的一些东西
// Validate that all properties marked as required are resolvable:
// see ConfigurablePropertyResolver#setRequiredProperties
getEnvironment().validateRequiredProperties();
// Store pre-refresh ApplicationListeners...
if (this.earlyApplicationListeners == null) {
// 创建空的集合存放监听事件
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 ();
2、obtainFreshBeanFactory(); 重点
obtainFreshBeanFactory();方法上面的注释说了，告诉子类刷新内部bean工厂
F7进入方法看到里面调用了2个方法，一个是刷新bean工厂，一个是获取bean工厂，主要是看refreshBeanFactory(), getBeanFactory()方法基本没做什么事
进入到refreshBeanFactory()方法里面，查看这个刷新BeanFactory的方法
/**
* This implementation performs an actual refresh of this contexts underlying
* bean factory, shutting down the previous bean factory (if any) and
* initializing a fresh bean factory for the next phase of the contexts lifecycle.
@Override
protected final void refreshBeanFactory() throws BeansException {
if (hasBeanFactory()) { // 这里很明显是判断有没有BeanFactory
// 如果已经有BeanFactory，就给销毁掉
destroyBeans();
closeBeanFactory();
try {
DefaultListableBeanFactory beanFactory = createBeanFactory(); // 准备创建BeanFactory，方法在下面看
beanFactory.setSerializationId(getId()); // 这个时候，上面一行代码已经创建好BeanFactory了，给BeanFactory存放序列化id
customizeBeanFactory(beanFactory); // 给BeanFactory设置自定义的功能，这个时候BeanFactory是空的，所以啥也没做
loadBeanDefinitions(beanFactory); // 合理非常重要，把bean的值放进BeanFactory进行加载过程，看下面的loadBeanDefinitions()方法介绍
this.beanFactory = beanFactory;
catch (IOException ex) {
throw new ApplicationContextException("I/O error parsing bean definition source for " + getDisplayName(), ex);
createBeanFactory()
createBeanFactory()方法，返回的是一个DefaultListableBeanFactory，这里最后返回的就是一个空对象，自己可以debug时候点进去看看
protected DefaultListableBeanFactory createBeanFactory() {
// getInternalParentBeanFactory() 返回的是个空的，所以直接看DefaultListableBeanFactory的构造方法，调用了supper()方法，里面调用到AbstractAutowireCapableBeanFactory()方法
return new DefaultListableBeanFactory(getInternalParentBeanFactory());
DefaultListableBeanFactory构造方法调用supper，里面调用了下面代码AbstractAutowireCapableBeanFactory()方法
public AbstractAutowireCapableBeanFactory() {
super(); // 调用父类创建抽象工厂，中间会把所有属性的值进行填充，可以自己在这里去具体细看
// 给ignoreDependencyInterface这个集合存放下面的3个Aware
ignoreDependencyInterface(BeanNameAware.class);
ignoreDependencyInterface(BeanFactoryAware.class);
ignoreDependencyInterface(BeanClassLoaderAware.class);
* Create a new AbstractAutowireCapableBeanFactory with the given parent.
* @param parentBeanFactory parent bean factory, or {@code null} if none
public AbstractAutowireCapableBeanFactory(@Nullable BeanFactory parentBeanFactory) {
this(); // 这个this()调用的是上面的AbstractAutowireCapableBeanFactory方法
setParentBeanFactory(parentBeanFactory); // 这个parentBeanFactory是空的
loadBeanDefinitions()
/**
* Loads the bean definitions via an XmlBeanDefinitionReader.
* @see org.springframework.beans.factory.xml.XmlBeanDefinitionReader
* @see #initBeanDefinitionReader
* @see #loadBeanDefinitions
@Override
protected void loadBeanDefinitions(DefaultListableBeanFactory beanFactory) throws BeansException, IOException {
// Create a new XmlBeanDefinitionReader for the given BeanFactory.创建XmlBeanDefinitionReader，可以自己调试进入查看做了什么
XmlBeanDefinitionReader beanDefinitionReader = new XmlBeanDefinitionReader(beanFactory);
// Configure the bean definition reader with this contexts
// resource loading environment.
beanDefinitionReader.setEnvironment(this.getEnvironment()); 给BeanDefinitionReader存放当前环境的对象
beanDefinitionReader.setResourceLoader(this); // 设置资源加载器，存放的是当前类的本身，是ClassPathXmlApplicationContext
beanDefinitionReader.setEntityResolver(new ResourceEntityResolver(this)); // 这个是为了处理xml文件，可以点进去看一下，主要是获取类加载器，把资源值加载进去，然后设置到EntityResolver里面
// Allow a subclass to provide custom initialization of the reader,
// then proceed with actually loading the bean definitions.
initBeanDefinitionReader(beanDefinitionReader); // 给beanDefinitionReader进行初始化工作，主要是进行最基本的一个验证xml，这里不是太难，可以自己点进去看看
loadBeanDefinitions(beanDefinitionReader); // 开始真正的加载过程，这里非常重要
loadBeanDefinitions()
/**
* Load the bean definitions with the given XmlBeanDefinitionReader.
* p The lifecycle of the bean factory is handled by the {@link #refreshBeanFactory}
* method; hence this method is just supposed to load and/or register bean definitions.
* @param reader the XmlBeanDefinitionReader to use
* @throws BeansException in case of bean registration errors
* @throws IOException if the required XML document isnt found
* @see #refreshBeanFactory
* @see #getConfigLocations
* @see #getResources
* @see #getResourcePatternResolver
protected void loadBeanDefinitions(XmlBeanDefinitionReader reader) throws BeansException, IOException {
Resource[] configResources = getConfigResources(); // 获取资源，这里是没有的，所以为空
if (configResources != null) {
reader.loadBeanDefinitions(configResources);
String[] configLocations = getConfigLocations(); // 这里是获取资源路径，就是获取到application.xml文件，想不起来的话看下面这个图，这时候肯定有值，所以进入下面判断里
if (configLocations != null) {
reader.loadBeanDefinitions(configLocations); // 开始进行整体的一个加载过程，看下面的具体代码
loadBeanDefinitions
@Override
public int loadBeanDefinitions(String... locations) throws BeanDefinitionStoreException {
Assert.notNull(locations, "Location array must not be null");
int count = 0;
for (String location : locations) {
count += loadBeanDefinitions(location); // 因为传的参数是数组，所以要遍历，看下面的loadBeanDefinitions具体实现代码，是又一个loadBeanDefinitions的重载方法代码
return count;
loadBeanDefinitions
public int loadBeanDefinitions(String location, @Nullable Set Resource actualResources) throws BeanDefinitionStoreException {
ResourceLoader resourceLoader = getResourceLoader(); // 前面已经知道了资源路径，所以在这里进行加载过来
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 {
// 这一行代码做了处理，把location加进去，然后获取Resources资源，自己点进去看看，调用的getResources方法在下面查看代码
Resource[] resources = ((ResourcePatternResolver) resourceLoader).getResources(location);
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;
getResources()
public Resource[] getResources(String locationPattern) throws IOException {
Assert.notNull(locationPattern, "Location pattern must not be null");
if (locationPattern.startsWith("classpath*:")) { // 判断传过来的是否以 classpath*: 为前缀，就是解析xml文件里的配置
return this.getPathMatcher().isPattern(locationPattern.substring("classpath*:".length())) ? this.findPathMatchingResources(locationPattern) : this.findAllClassPathResources(locationPattern.substring("classpath*:".length()));
} else {
// 判断是否是 war: 或者 */ ， 都不是
int prefixEnd = locationPattern.startsWith("war:") ? locationPattern.indexOf("*/") + 1 : locationPattern.indexOf(58) + 1;
// 既然都不是，所以使用后面判断代码，当前的这个值加载回来，获取当前资源路径，把资源路径放到Resource对象里面
return this.getPathMatcher().isPattern(locationPattern.substring(prefixEnd)) ? this.findPathMatchingResources(locationPattern) : new Resource[]{this.getResourceLoader().getResource(locationPattern)};
public Resource getResource(String location) {
Assert.notNull(location, "Location must not be null");
Iterator var2 = this.getProtocolResolvers().iterator();
Resource resource;
do {
if (!var2.hasNext()) {
if (location.startsWith("/")) {
return this.getResourceByPath(location);
if (location.startsWith("classpath:")) {
return new ClassPathResource(location.substring("classpath:".length()), this.getClassLoader());
try {
URL url = new URL(location);
return (Resource)(ResourceUtils.isFileURL(url) ? new FileUrlResource(url) : new UrlResource(url));
} catch (MalformedURLException var5) {
// 上面条件都不满足，所以会执行下面这行，通过路径返回Resource资源，点进去就可以看到处理过程了
return this.getResourceByPath(location);
ProtocolResolver protocolResolver = (ProtocolResolver)var2.next();
resource = protocolResolver.resolve(location, this);
} while(resource == null);
return resource;
通过路径获取到resources对象后，又调用了loadBeanDefinitions()重载方法，上面执行调用时穿入的参数是字符串，现在传入的参数是资源，执行到这个方法来看下面源码
loadBeanDefinitions
public 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);
// 现在什么都没做，所以这个里面的ThreadLocal啥也没干，currentResources是空的
Set EncodedResource currentResources = this.resourcesCurrentlyBeingLoaded.get();
// 把encodedResource，也就是application.xml给加入到currentResources里面
if (!currentResources.add(encodedResource)) {
throw new BeanDefinitionStoreException(
"Detected cyclic loading of " + encodedResource + " - check your import definitions!");
// 获取输入流对象，读取xml文件
try (InputStream inputStream = encodedResource.getResource().getInputStream()) {
InputSource inputSource = new InputSource(inputStream);
if (encodedResource.getEncoding() != null) {
inputSource.setEncoding(encodedResource.getEncoding());
// 这里开始真正执行，跳到下面的doLoadBeanDefinitions代码去看吧
return doLoadBeanDefinitions(inputSource, encodedResource.getResource());
catch (IOException ex) {
throw new BeanDefinitionStoreException(
"IOException parsing XML document from " + encodedResource.getResource(), ex);
finally {
currentResources.remove(encodedResource);
if (currentResources.isEmpty()) {
this.resourcesCurrentlyBeingLoaded.remove();
doLoadBeanDefinitions()
protected int doLoadBeanDefinitions(InputSource inputSource, Resource resource)
throws BeanDefinitionStoreException {
try {
// 按照文档方式读取xml配置资源对象，主要是验证配置文件是否规范正确，先验证头信息，再验证其他配置信息，
// 最后得到一个DocumentBuilder对象，可以通过这个对象过去到配置文件的属性值了
Document doc = doLoadDocument(inputSource, resource); // 具体是把xml解析一下成Document，它就是个字符串，可以自己点进去细看一下
int count = registerBeanDefinitions(doc, resource); // 点进去看源码，看下面代码
if (logger.isDebugEnabled()) {
logger.debug("Loaded " + count + " bean definitions from " + resource);
return count; // 这里返回的是1，因为我只有一个person对象
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);
返回count为1，具体整个过程要下面的内容，到这个位置结束，就可以知道具体实现了
registerBeanDefinitions()
/**
* Register the bean definitions contained in the given DOM document.
* Called by {@code loadBeanDefinitions}.
* p Creates a new instance of the parser class and invokes
* {@code registerBeanDefinitions} on it.
* @param doc the DOM document
* @param resource the resource descriptor (for context information)
* @return the number of bean definitions found
* @throws BeanDefinitionStoreException in case of parsing errors
* @see #loadBeanDefinitions
* @see #setDocumentReaderClass
* @see BeanDefinitionDocumentReader#registerBeanDefinitions
public int registerBeanDefinitions(Document doc, Resource resource) throws BeanDefinitionStoreException {
// 创建一个BeanDefinitionDocumentReader，这个和前面的BeanDefinitionReader是不一样的，不要搞混了
BeanDefinitionDocumentReader documentReader = createBeanDefinitionDocumentReader();
// getRegistry()是获取BeanFactory，.getBeanDefinitionCount 是获取注册了多少个BeanDefinition
int countBefore = getRegistry().getBeanDefinitionCount(); // 这个时候是0个，因为还没开始注册
// 开始往里面注册，有个createReaderContext(resource)，这次使用鼠标点进去，看下面的createReaderContext方法的源码
// 看完createReaderContext(resource)后发现其实就是一个赋值的操作，然后看registerBeanDefinitions的方法
documentReader.registerBeanDefinitions(doc, createReaderContext(resource));
return getRegistry().getBeanDefinitionCount() - countBefore;
createReaderContext:
public XmlReaderContext createReaderContext(Resource resource) {
// 查看XmlReaderContext类上面的注释，
return new XmlReaderContext(resource, this.problemReporter, this.eventListener,
// 调用的下面的getNamespaceHandlerResolver()方法
this.sourceExtractor, this, getNamespaceHandlerResolver());
public NamespaceHandlerResolver getNamespaceHandlerResolver() {
if (this.namespaceHandlerResolver == null) {
// 调用了下面的createDefaultNamespaceHandlerResolver()方法
this.namespaceHandlerResolver = createDefaultNamespaceHandlerResolver();
return this.namespaceHandlerResolver;
protected NamespaceHandlerResolver createDefaultNamespaceHandlerResolver() {
ClassLoader cl = (getResourceLoader() != null ? getResourceLoader().getClassLoader() : getBeanClassLoader());
// 点进去看DefaultNamespaceHandlerResolver的源码，这个就比较好玩了
return new DefaultNamespaceHandlerResolver(cl);
通过DefaultNamespaceHandlerResolver类上面的注释可以知道，接口的默认实现，是根据映射将命名空间uri解析为实现类，包含在映射文件中。
/**
* Default implementation of the {@link NamespaceHandlerResolver} interface.
* Resolves namespace URIs to implementation classes based on the mappings
* contained in mapping file.
* p By default, this implementation looks for the mapping file at
* {@code META-INF/spring.handlers}, but this can be changed using the
* {@link #DefaultNamespaceHandlerResolver(ClassLoader, String)} constructor.
* @author Rob Harrop
* @author Juergen Hoeller
* @since 2.0
* @see NamespaceHandler
* @see DefaultBeanDefinitionDocumentReader
public class DefaultNamespaceHandlerResolver implements NamespaceHandlerResolver {
* The location to look for the mapping files. Can be present in multiple JAR files.
// 看这个"META-INF/spring.handlers"的值，
public static final String DEFAULT_HANDLER_MAPPINGS_LOCATION = "META-INF/spring.handlers";
。。。。。。
在这个META-INF/spring.handlers路径下找一找对应的spring.handlers文件里面都有很多对应的处理器，这些处理器就这么通过文件给拿过来的
这些就对应的xml配置文件里面的命名空间，所以xml文件的格式为什么要有固定的正确格式，不是白写的
registerBeanDefinitions：
@Override
public void registerBeanDefinitions(Document doc, XmlReaderContext readerContext) {
this.readerContext = readerContext;
// doc.getDocumentElement()是获取到xml文件里的父级标签
doRegisterBeanDefinitions(doc.getDocumentElement()); // 所有带do的方法都是实际干活的方法，所以这个挺重要，看下面代码
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;
// 开始赋值，这时候可以点进去看到 new了一个 BeanDefinitionParserDelegate，其实就是得到xml配置文件里对应的标签的值，如下图
this.delegate = createDelegate(getReaderContext(), root, parent);
if (this.delegate.isDefaultNamespace(root)) { // 判断是否是默认的命名空间
// PROFILE_ATTRIBUTE = "profile"，PROFILE_ATTRIBUTE的值就是"profile"，想想springboot时候，通过它来设置使用对应的环境切换，dev啦，sit啦
String profileSpec = root.getAttribute(PROFILE_ATTRIBUTE);
// 这里是同于空的，所以进不到这个判断里
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); // 这里什么都没做，可以点进去看看是个空的，没有具体的实现，所以就是让我们自己去扩展的
parseBeanDefinitions(root, this.delegate); // 这里是个核心，开始去解析BeanDefinitions了，看下面的源码
postProcessXml(root); // 这里也是空的，没有具体的实现，让自己去扩展用的
this.delegate = parent;
BeanDefinitionParserDelegate类：
BeanDefinitions()
protected void parseBeanDefinitions(Element root, BeanDefinitionParserDelegate delegate) {
if (delegate.isDefaultNamespace(root)) {
// 获取beans里面所有标签
NodeList nl = root.getChildNodes();
for (int i = 0; i nl.getLength(); i++) {
Node node = nl.item(i);
// 判断当前的一行是不是Element，这里要对应你写的xml配置文件，命名空间完后的内容
if (node instanceof Element) { // 如果这一行不为换行或注释，就会进来
Element ele = (Element) node;
// 这些都在for循环当中，也就是在循环遍历每一行，看是否是默认beans标签里面的子标签
if (delegate.isDefaultNamespace(ele)) { // 判断是否属于默认的，也就是 beans 标签里面的
parseDefaultElement(ele, delegate); // 我的xml配置文件里写的就是bean标签，所以就进来了，看下面的parseDefaultElement()方法代码
else { // 如果这一行不是属于 beans 标签里面的，是其他定义的，就会到下面
delegate.parseCustomElement(ele);
else {
delegate.parseCustomElement(root);
parseDefaultElement()方法：这个里面就比较熟悉了
private void parseDefaultElement(Element ele, BeanDefinitionParserDelegate delegate) {
if (delegate.nodeNameEquals(ele, IMPORT_ELEMENT)) { // 判断是否是import标签
importBeanDefinitionResource(ele);
else if (delegate.nodeNameEquals(ele, ALIAS_ELEMENT)) { // 判断是否是alias标签
processAliasRegistration(ele);
else if (delegate.nodeNameEquals(ele, BEAN_ELEMENT)) { // 判断是否是bean标签，很显然是，就执行下面方法
processBeanDefinition(ele, delegate); // 看下面的方法源码
else if (delegate.nodeNameEquals(ele, NESTED_BEANS_ELEMENT)) {
// recurse
doRegisterBeanDefinitions(ele);
processBeanDefinition()
protected void processBeanDefinition(Element ele, BeanDefinitionParserDelegate delegate) {
// 调用了parseBeanDefinitionElement(ele)，可以看下源码，最后调了parseBeanDefinitionElement()方法，看下面方法源码图
BeanDefinitionHolder bdHolder = delegate.parseBeanDefinitionElement(ele);
if (bdHolder != null) {
bdHolder = delegate.decorateBeanDefinitionIfRequired(ele, bdHolder);
try {
// Register the final decorated instance.
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));
parseBeanDefinitionElement():
可以看到通过bean标签获取到了具体的属性值，因为containingBean是空的，所以又调用了checkNameUniqueness()方法，其实里面就是验证bean属性值的唯一性
parseBeanDefinitionElement()方法的源码:
@Nullable
public BeanDefinitionHolder parseBeanDefinitionElement(Element ele, @Nullable BeanDefinition containingBean) {
String id = ele.getAttribute(ID_ATTRIBUTE);
String nameAttr = ele.getAttribute(NAME_ATTRIBUTE);
List String aliases = new ArrayList ();
if (StringUtils.hasLength(nameAttr)) {
String[] nameArr = StringUtils.tokenizeToStringArray(nameAttr, MULTI_VALUE_ATTRIBUTE_DELIMITERS);
aliases.addAll(Arrays.asList(nameArr));
String beanName = id;
if (!StringUtils.hasText(beanName) !aliases.isEmpty()) {
beanName = aliases.remove(0);
if (logger.isTraceEnabled()) {
logger.trace("No XML id specified - using " + beanName +
" as bean name and " + aliases + " as aliases");
if (containingBean == null) {
checkNameUniqueness(beanName, aliases, ele);
// 开始执行parseBeanDefinitionElement方法，看下面方法的源代码吧。。
AbstractBeanDefinition beanDefinition = parseBeanDefinitionElement(ele, beanName, containingBean);
if (beanDefinition != null) {
if (!StringUtils.hasText(beanName)) { // 这里beanName是person属性。
郑重声明：本文由网友发布，不代表盛行IT的观点，版权归原作者所有，仅为传播更多信息之目的，如有侵权请联系，我们将第一时间修改或删除，多谢。