spring ioc容器初始化

IOC容器的初始化分为三个过程实现：

• 第一个过程是Resource资源定位。这个Resouce指的是BeanDefinition的资源定位。这个过程就是容器找数据的过程，就像水桶装水需要先找到水一样。

• 第二个过程是BeanDefinition的载入过程。这个载入过程是把用户定义好的Bean表示成Ioc容器内部的数据结构，而这个容器内部的数据结构就是BeanDefition。

• 第三个过程是向IOC容器注册这些BeanDefinition的过程，这个过程就是将前面的BeanDefition保存到HashMap中的过程。

上面提到的过程一般是不包括Bean的依赖注入的实现。在Spring中，Bean的载入和依赖注入是两个独立的过程。依赖注入一般发生在应用第一次通过getBean向容器索取Bean的时候。下面的一张图描述了这三个过程调用的主要方法，图中的四个过程其实描述的是上面的第二个过程和第三个过程：

1 Resource定位

下面来看看主要的三个ApplicationContext的实现类是如何定位资源的，也就是找到我们通常所说“applicationContetx.xml”等配置文件的。

1.1 ClassPathXmlApplicationContext与FileSystemXmlApplicationContext

这两个类都是非Web容器时，常用的ApplicationContext类。他们很相似，所有的构造方法都在重载调用一段核心的代码。这段代码虽然很短，但是其中是一个很复杂的执行过程，它完成了IOC容器的初始化。

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1. super(parent);  
2.         setConfigLocations(configLocations);  
3.         if (refresh) {  
4.             refresh();  
5.         }  

1. super(parent);

2. setConfigLocations(configLocations);

3. if (refresh) {

4. refresh();

5. }

这其中的setConfigLocations方法就是在进行资源定位。这个方法在AbstractRefreshableConfigApplicationContext类中实现。这个方法首先进行了非空了检验。这个Assert是Spring框架的一个工具类，这里面进行了一个非空判断。然后对这个路径进行了一些处理。这样就完成了资源的定位。这个定位其实就是使用者主动把配置文件的位置告诉Spring框架。

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1. if (locations != null) {  
2.             Assert.noNullElements(locations, "Config locations must not be null");  
3.             this.configLocations = new String[locations.length];  
4.             for (int i = 0; i < locations.length; i++) {  
5.                 this.configLocations[i] = resolvePath(locations[i]).trim();  
6.             }  
7.         }  
8.         else {  
9.             this.configLocations = null;  
10.         }  

1. if (locations != null) {

2. Assert.noNullElements(locations, "Config locations must not be null");

3. this.configLocations = new String[locations.length];

4. for (int i = 0; i < locations.length; i++) {

5. this.configLocations[i] = resolvePath(locations[i]).trim();

6. }

7. }

8. else {

9. this.configLocations = null;

10. }

1.2 XmlWebApplicationContext

这个类是web容器初始化spring IOC容器的类。对于web应用来说，我们通常是不是直接去初始化这个容器的，它的装载是一个自动进行的过程。这是因为我们在web.xml中配置了这样一句话，这其实就是spring的入口

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1.   
2.         org.springframework.web.context.ContextLoaderListener  
3.       

2. org.springframework.web.context.ContextLoaderListener

 

（1）下面来看这个类ContextLoaderListener，从它的定义就能看出，这是一个ServletContextListener，它的核心方法就是下面的contextInitialized事件，也就是当web容器初始化的时候，spring容器也进行了初始化。

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1. public class ContextLoaderListener extends ContextLoader implements ServletContextListener  

public class ContextLoaderListener extends ContextLoader implements ServletContextListener

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1. /** 
2.  * Initialize the root web application context. 
3.  */  
4. @Override  
5. public void contextInitialized(ServletContextEvent event) {  
6.     initWebApplicationContext(event.getServletContext());  
7. }  

1. /**

2. * Initialize the root web application context.

3. */

4. @Override

5. public void contextInitialized(ServletContextEvent event) {

6. initWebApplicationContext(event.getServletContext());

7. }

这个方法将servletContext作为参数传入，它的目标就是为了读取web.xml配置文件，找到我们对spring的配置。

（2）下面来看initWebApplicationContext方法，它完成了对webApplictionContext的初始化工作。这个方法里的有比较重要的几段代码，他们主要完成了webAppliction构建，参数的注入，以及保存

• 构建webApplictionContext

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1. if (this.context == null) {  
2.                 this.context = createWebApplicationContext(servletContext);  
3.             }  

1. if (this.context == null) {

2. this.context = createWebApplicationContext(servletContext);

3. }

这段代码看字面意思就知道是新建了一个webApplicationContext。它是由一个工具类产生一个新的wac,这个方法中调用了determineContextClass方法，它决定了容器初始化为哪种类型的ApplicationContext，因为我们可以在web.xml中对这种类型进行指定。而如果没有指定的话，就将使用默认的XmlWebApplicationContext。

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1. protected Class determineContextClass(ServletContext servletContext) {  
2.         String contextClassName = servletContext.getInitParameter(CONTEXT_CLASS_PARAM);  
3.         if (contextClassName != null) {  
4.             try {  
5.                 return ClassUtils.forName(contextClassName, ClassUtils.getDefaultClassLoader());  
6.             }  
7.             catch (ClassNotFoundException ex) {  
8.                 throw new ApplicationContextException(  
9.                         "Failed to load custom context class [" + contextClassName + "]", ex);  
10.             }  
11.         }  
12.         else {  
13.             contextClassName = defaultStrategies.getProperty(WebApplicationContext.class.getName());  
14.             try {  
15.                 return ClassUtils.forName(contextClassName, ContextLoader.class.getClassLoader());  
16.             }  
17.             catch (ClassNotFoundException ex) {  
18.                 throw new ApplicationContextException(  
19.                         "Failed to load default context class [" + contextClassName + "]", ex);  
20.             }  
21.         }  
22.     }  

1. protected Class determineContextClass(ServletContext servletContext) {

2. String contextClassName = servletContext.getInitParameter(CONTEXT_CLASS_PARAM);

3. if (contextClassName != null) {

4. try {

5. return ClassUtils.forName(contextClassName, ClassUtils.getDefaultClassLoader());

6. }

7. catch (ClassNotFoundException ex) {

8. throw new ApplicationContextException(

9. "Failed to load custom context class [" + contextClassName + "]", ex);

10. }

11. }

12. else {

13. contextClassName = defaultStrategies.getProperty(WebApplicationContext.class.getName());

14. try {

15. return ClassUtils.forName(contextClassName, ContextLoader.class.getClassLoader());

16. }

17. catch (ClassNotFoundException ex) {

18. throw new ApplicationContextException(

19. "Failed to load default context class [" + contextClassName + "]", ex);

20. }

21. }

22. }

• 注入参数，初始化这个空的容器 。这个过程的入口是configureAndRefreshWebApplicationContext这个方法中完成了wac的Id设置，将servletContext注入到wac中，还有最重要的方法，就是setConfigLocation.这里从web.xml中寻找指定的配置文件的位置，也就是我们通常配置的“contextConfigLocation”属性

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1. String configLocationParam = sc.getInitParameter(CONFIG_LOCATION_PARAM);  
2.         if (configLocationParam != null) {  
3.             wac.setConfigLocation(configLocationParam);  
4.         }  

1. String configLocationParam = sc.getInitParameter(CONFIG_LOCATION_PARAM);

2. if (configLocationParam != null) {

3. wac.setConfigLocation(configLocationParam);

4. }

那么如果没有指定呢？在XMLWebApplicationContext中这样一些常量，他们表示了配置文件的默认位置

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1. /** Default config location for the root context */  
2.     public static final String DEFAULT_CONFIG_LOCATION = "/WEB-INF/applicationContext.xml";  
3.   
4.     /** Default prefix for building a config location for a namespace */  
5.     public static final String DEFAULT_CONFIG_LOCATION_PREFIX = "/WEB-INF/";  
6.   
7.     /** Default suffix for building a config location for a namespace */  
8.     public static final String DEFAULT_CONFIG_LOCATION_SUFFIX = ".xml";  

1. /** Default config location for the root context */

2. public static final String DEFAULT_CONFIG_LOCATION = "/WEB-INF/applicationContext.xml";

4. /** Default prefix for building a config location for a namespace */

5. public static final String DEFAULT_CONFIG_LOCATION_PREFIX = "/WEB-INF/";

7. /** Default suffix for building a config location for a namespace */

8. public static final String DEFAULT_CONFIG_LOCATION_SUFFIX = ".xml";

 

 

• spring容器初始化完成后，放入serverletContext中，这样在web容器中就可以拿到applicationContext

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1. servletContext.setAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE, this.context);  

servletContext.setAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE, this.context);

2 BeanDefinition载入

这个过程是最繁琐，也是最重要的一个过程。这一个过程分为以下几步，

• 构造一个BeanFactory,也就是IOC容器

• 调用XML解析器得到document对象

•  按照Spring的规则解析BeanDefition

对于以上过程，都需要一个入口，也就是前面提到的refresh()方法，这个方法AbstractApplicationContext类中，它描述了整个ApplicationContext的初始化过程，比如BeanFactory的更新，MessgaeSource和PostProcessor的注册等等。它更像是个初始化的提纲，这个过程为Bean的声明周期管理提供了条件。

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1. public void refresh() throws BeansException, IllegalStateException {  
2.         synchronized (this.startupShutdownMonitor) {  
3.             // Prepare this context for refreshing.  
4.             prepareRefresh();  
5.   
6.             // Tell the subclass to refresh the internal bean factory.  
7.             ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();  
8.   
9.             // Prepare the bean factory for use in this context.  
10.             prepareBeanFactory(beanFactory);  
11.   
12.             try {  
13.                 // Allows post-processing of the bean factory in context subclasses.  
14.                 postProcessBeanFactory(beanFactory);  
15.   
16.                 // Invoke factory processors registered as beans in the context.  
17.                 invokeBeanFactoryPostProcessors(beanFactory);  
18.   
19.                 // Register bean processors that intercept bean creation.  
20.                 registerBeanPostProcessors(beanFactory);  
21.   
22.                 // Initialize message source for this context.  
23.                 initMessageSource();  
24.   
25.                 // Initialize event multicaster for this context.  
26.                 initApplicationEventMulticaster();  
27.   
28.                 // Initialize other special beans in specific context subclasses.  
29.                 onRefresh();  
30.   
31.                 // Check for listener beans and register them.  
32.                 registerListeners();  
33.   
34.                 // Instantiate all remaining (non-lazy-init) singletons.  
35.                 finishBeanFactoryInitialization(beanFactory);  
36.   
37.                 // Last step: publish corresponding event.  
38.                 finishRefresh();  
39.             }  
40.   
41.             catch (BeansException ex) {  
42.                 logger.warn("Exception encountered during context initialization - cancelling refresh attempt", ex);  
43.   
44.                 // Destroy already created singletons to avoid dangling resources.  
45.                 destroyBeans();  
46.   
47.                 // Reset 'active' flag.  
48.                 cancelRefresh(ex);  
49.   
50.                 // Propagate exception to caller.  
51.                 throw ex;  
52.             }  
53.         }  
54.     }  

1. public void refresh() throws BeansException, IllegalStateException {

2. synchronized (this.startupShutdownMonitor) {

3. // Prepare this context for refreshing.

4. prepareRefresh();

6. // Tell the subclass to refresh the internal bean factory.

7. ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();

9. // Prepare the bean factory for use in this context.

10. prepareBeanFactory(beanFactory);

12. try {

13. // Allows post-processing of the bean factory in context subclasses.

14. postProcessBeanFactory(beanFactory);

16. // Invoke factory processors registered as beans in the context.

17. invokeBeanFactoryPostProcessors(beanFactory);

19. // Register bean processors that intercept bean creation.

20. registerBeanPostProcessors(beanFactory);

22. // Initialize message source for this context.

23. initMessageSource();

25. // Initialize event multicaster for this context.

26. initApplicationEventMulticaster();

28. // Initialize other special beans in specific context subclasses.

29. onRefresh();

31. // Check for listener beans and register them.

32. registerListeners();

34. // Instantiate all remaining (non-lazy-init) singletons.

35. finishBeanFactoryInitialization(beanFactory);

37. // Last step: publish corresponding event.

38. finishRefresh();

39. }

41. catch (BeansException ex) {

42. logger.warn("Exception encountered during context initialization - cancelling refresh attempt", ex);

44. // Destroy already created singletons to avoid dangling resources.

45. destroyBeans();

47. // Reset 'active' flag.

48. cancelRefresh(ex);

50. // Propagate exception to caller.

51. throw ex;

52. }

53. }

54. }

2.1 构建IOC容器

这个过程的入口是refresh方法中的obtainFreshBeanFactory（）方法。整个过程构建了一个DefaultListableBeanFactory对象，这也就是IOC容器的实际类型。这一过程的核心如下：

2.1.1 obtainFreshBeanFactory

这个方法的作用是通知子类去初始化ioc容器，它调用了AbstractRefreshableApplicationContext的refreshBeanFactory 方法 进行后续工作。同时在日志是debug模式的时候，向日志输出初始化结果。

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1. protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {  
2.         refreshBeanFactory();  
3.         ConfigurableListableBeanFactory beanFactory = getBeanFactory();  
4.         if (logger.isDebugEnabled()) {  
5.             logger.debug("Bean factory for " + getDisplayName() + ": " + beanFactory);  
6.         }  
7.         return beanFactory;  
8.     }  

1. protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {

2. refreshBeanFactory();

3. ConfigurableListableBeanFactory beanFactory = getBeanFactory();

4. if (logger.isDebugEnabled()) {

5. logger.debug("Bean factory for " + getDisplayName() + ": " + beanFactory);

6. }

7. return beanFactory;

8. }

2.1.2 refreshBeanFactory

这个方法在创建IOC容器前，如果已经有容器存在，那么需要将已有的容器关闭和销毁，保证refresh之后使用的是新建立的容器。同时 在创建了空的IOC容器后，开始了对BeanDefitions的载入

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1. protected final void refreshBeanFactory() throws BeansException {  
2.         if (hasBeanFactory()) {  
3.             destroyBeans();  
4.             closeBeanFactory();  
5.         }  
6.         try {  
7.             DefaultListableBeanFactory beanFactory = createBeanFactory();//创建了IOC容器  
8.             beanFactory.setSerializationId(getId());  
9.             customizeBeanFactory(beanFactory);  
10.             loadBeanDefinitions(beanFactory);// 启动对BeanDefitions的载入  
11.             synchronized (this.beanFactoryMonitor) {  
12.                 this.beanFactory = beanFactory;  
13.             }  
14.         }  
15.         catch (IOException ex) {  
16.             throw new ApplicationContextException("I/O error parsing bean definition source for " + getDisplayName(), ex);  
17.         }  
18.     }  

1. protected final void refreshBeanFactory() throws BeansException {

2. if (hasBeanFactory()) {

3. destroyBeans();

4. closeBeanFactory();

5. }

6. try {

7. DefaultListableBeanFactory beanFactory = createBeanFactory();//创建了IOC容器

8. beanFactory.setSerializationId(getId());

9. customizeBeanFactory(beanFactory);

10. loadBeanDefinitions(beanFactory);// 启动对BeanDefitions的载入

11. synchronized (this.beanFactoryMonitor) {

12. this.beanFactory = beanFactory;

13. }

14. }

15. catch (IOException ex) {

16. throw new ApplicationContextException("I/O error parsing bean definition source for " + getDisplayName(), ex);

17. }

18. }

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1. protected DefaultListableBeanFactory createBeanFactory() {  
2.         return new DefaultListableBeanFactory(getInternalParentBeanFactory());  
3.     }  

1. protected DefaultListableBeanFactory createBeanFactory() {

2. return new DefaultListableBeanFactory(getInternalParentBeanFactory());

3. }

2.2 解析XML文件

对于Spring，我们通常使用xml形式的配置文件定义Bean，在对BeanDefition载入之前，首先需要进行的就是XML文件的解析。整个过程的核心方法如下：

2.2.1 loadBeanDefinitions(DefaultListableBeanFactory beanFactory)

这里构造一个XmlBeanDefinitionReader对象，把解析工作交给他去实现

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1. protected void loadBeanDefinitions(DefaultListableBeanFactory beanFactory) throws BeansException, IOException {  
2.         // 定义一个XmlBeanDefinitionReader对象 用于解析XML  
3.         XmlBeanDefinitionReader beanDefinitionReader = new XmlBeanDefinitionReader(beanFactory);  
4.   
5.         //进行一些初始化和环境配置  
6.         // Configure the bean definition reader with this context's  
7.         // resource loading environment.  
8.         beanDefinitionReader.setEnvironment(this.getEnvironment());  
9.         beanDefinitionReader.setResourceLoader(this);  
10.         beanDefinitionReader.setEntityResolver(new ResourceEntityResolver(this));  
11.   
12.         // Allow a subclass to provide custom initialization of the reader,  
13.         // then proceed with actually loading the bean definitions.  
14.         initBeanDefinitionReader(beanDefinitionReader);  
15.         //解析入口  
16.         loadBeanDefinitions(beanDefinitionReader);  
17.     }  

1. protected void loadBeanDefinitions(DefaultListableBeanFactory beanFactory) throws BeansException, IOException {

2. // 定义一个XmlBeanDefinitionReader对象 用于解析XML

3. XmlBeanDefinitionReader beanDefinitionReader = new XmlBeanDefinitionReader(beanFactory);

5. //进行一些初始化和环境配置

6. // Configure the bean definition reader with this context's

7. // resource loading environment.

8. beanDefinitionReader.setEnvironment(this.getEnvironment());

9. beanDefinitionReader.setResourceLoader(this);

10. beanDefinitionReader.setEntityResolver(new ResourceEntityResolver(this));

12. // Allow a subclass to provide custom initialization of the reader,

13. // then proceed with actually loading the bean definitions.

14. initBeanDefinitionReader(beanDefinitionReader);

15. //解析入口

16. loadBeanDefinitions(beanDefinitionReader);

17. }

2.2.2 loadBeanDefinitions

（1） AbstractXmlApplicationContext类 ，利用reader的方法解析，向下调用（Load the bean definitions with the given XmlBeanDefinitionReader.）

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1. protected void loadBeanDefinitions(XmlBeanDefinitionReader reader) throws BeansException, IOException {  
2.         Resource[] configResources = getConfigResources();  
3.         if (configResources != null) {  
4.             reader.loadBeanDefinitions(configResources);  
5.         }  
6.         String[] configLocations = getConfigLocations();  
7.         if (configLocations != null) {  
8.             reader.loadBeanDefinitions(configLocations);  
9.         }  
10.     }  

1. protected void loadBeanDefinitions(XmlBeanDefinitionReader reader) throws BeansException, IOException {

2. Resource[] configResources = getConfigResources();

3. if (configResources != null) {

4. reader.loadBeanDefinitions(configResources);

5. }

6. String[] configLocations = getConfigLocations();

7. if (configLocations != null) {

8. reader.loadBeanDefinitions(configLocations);

9. }

10. }

（2） AbstractBeanDefinitionReader 类 解析Resource  向下调用

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1. public int loadBeanDefinitions(Resource... resources) throws BeanDefinitionStoreException {  
2.         Assert.notNull(resources, "Resource array must not be null");  
3.         int counter = 0;  
4.         for (Resource resource : resources) {  
5.             counter += loadBeanDefinitions(resource);  
6.         }  
7.         return counter;  
8.     }  

1. public int loadBeanDefinitions(Resource... resources) throws BeanDefinitionStoreException {

2. Assert.notNull(resources, "Resource array must not be null");

3. int counter = 0;

4. for (Resource resource : resources) {

5. counter += loadBeanDefinitions(resource);

6. }

7. return counter;

8. }

（3） XmlBeanDefinitionReader 

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1. public int loadBeanDefinitions(Resource resource) throws BeanDefinitionStoreException {  
2.         return loadBeanDefinitions(new EncodedResource(resource));  
3.     }  

1. public int loadBeanDefinitions(Resource resource) throws BeanDefinitionStoreException {

2. return loadBeanDefinitions(new EncodedResource(resource));

3. }

在下面方法得到了XML文件，并打开IO流，准备进行解析。实际向下调用

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1. public int loadBeanDefinitions(EncodedResource encodedResource) throws BeanDefinitionStoreException {  
2.         Assert.notNull(encodedResource, "EncodedResource must not be null");  
3.         if (logger.isInfoEnabled()) {  
4.             logger.info("Loading XML bean definitions from " + encodedResource.getResource());  
5.         }  
6.   
7.         Set currentResources = this.resourcesCurrentlyBeingLoaded.get();  
8.         if (currentResources == null) {  
9.             currentResources = new HashSet(4);  
10.             this.resourcesCurrentlyBeingLoaded.set(currentResources);  
11.         }  
12.         if (!currentResources.add(encodedResource)) {  
13.             throw new BeanDefinitionStoreException(  
14.                     "Detected cyclic loading of " + encodedResource + " - check your import definitions!");  
15.         }  
16.         try {  
17.             InputStream inputStream = encodedResource.getResource().getInputStream();  
18.             try {  
19.                 InputSource inputSource = new InputSource(inputStream);  
20.                 if (encodedResource.getEncoding() != null) {  
21.                     inputSource.setEncoding(encodedResource.getEncoding());  
22.                 }  
23.                 return doLoadBeanDefinitions(inputSource, encodedResource.getResource());  
24.             }  
25.             finally {  
26.                 inputStream.close();  
27.             }  
28.         }  
29.         catch (IOException ex) {  
30.             throw new BeanDefinitionStoreException(  
31.                     "IOException parsing XML document from " + encodedResource.getResource(), ex);  
32.         }  
33.         finally {  
34.             currentResources.remove(encodedResource);  
35.             if (currentResources.isEmpty()) {  
36.                 this.resourcesCurrentlyBeingLoaded.remove();  
37.             }  
38.         }  
39.     }  

1. public int loadBeanDefinitions(EncodedResource encodedResource) throws BeanDefinitionStoreException {

2. Assert.notNull(encodedResource, "EncodedResource must not be null");

3. if (logger.isInfoEnabled()) {

4. logger.info("Loading XML bean definitions from " + encodedResource.getResource());

5. }

7. Set currentResources = this.resourcesCurrentlyBeingLoaded.get();

8. if (currentResources == null) {

9. currentResources = new HashSet(4);

10. this.resourcesCurrentlyBeingLoaded.set(currentResources);

11. }

12. if (!currentResources.add(encodedResource)) {

13. throw new BeanDefinitionStoreException(

14. "Detected cyclic loading of " + encodedResource + " - check your import definitions!");

15. }

16. try {

17. InputStream inputStream = encodedResource.getResource().getInputStream();

18. try {

19. InputSource inputSource = new InputSource(inputStream);

20. if (encodedResource.getEncoding() != null) {

21. inputSource.setEncoding(encodedResource.getEncoding());

22. }

23. return doLoadBeanDefinitions(inputSource, encodedResource.getResource());

24. }

25. finally {

26. inputStream.close();

27. }

28. }

29. catch (IOException ex) {

30. throw new BeanDefinitionStoreException(

31. "IOException parsing XML document from " + encodedResource.getResource(), ex);

32. }

33. finally {

34. currentResources.remove(encodedResource);

35. if (currentResources.isEmpty()) {

36. this.resourcesCurrentlyBeingLoaded.remove();

37. }

38. }

39. }

（4） doLoadBeanDefinitions

下面是它的核心方法，第一句调用Spring解析XML的方法得到document对象，而第二句则是载入BeanDefitions的入口

[java] view plain copy

1. try {  
2.             Document doc = doLoadDocument(inputSource, resource);  
3.             return registerBeanDefinitions(doc, resource);  
4.         }  

1. try {

2. Document doc = doLoadDocument(inputSource, resource);

3. return registerBeanDefinitions(doc, resource);

4. }

2.3 解析Spring数据结构

这一步是将document对象解析成spring内部的bean结构，实际上是AbstractBeanDefinition对象。这个对象的解析结果放入BeanDefinitionHolder中，而整个过程是由BeanDefinitionParserDelegate完成。

2.3.1 registerBeanDefinitions

解析BeanDefinitions的入口，向下调用doRegisterBeanDefinitions方法

[java] view plain copy

1. public void registerBeanDefinitions(Document doc, XmlReaderContext readerContext) {  
2.         this.readerContext = readerContext;  
3.         logger.debug("Loading bean definitions");  
4.         Element root = doc.getDocumentElement();  
5.         doRegisterBeanDefinitions(root);  
6.     }  

1. public void registerBeanDefinitions(Document doc, XmlReaderContext readerContext) {

2. this.readerContext = readerContext;

3. logger.debug("Loading bean definitions");

4. Element root = doc.getDocumentElement();

5. doRegisterBeanDefinitions(root);

6. }

2.3.2 doRegisterBeanDefinitions

定义了BeanDefinitionParserDelegate 解析处理器对象，向下调用parseBeanDefinitions 方法

[java] view plain copy

1. protected void doRegisterBeanDefinitions(Element root) {  
2.         // Any nested  elements will cause recursion in this method. In  
3.         // order to propagate and preserve  default-* attributes correctly,  
4.         // keep track of the current (parent) delegate, which may be null. Create  
5.         // the new (child) delegate with a reference to the parent for fallback purposes,  
6.         // then ultimately reset this.delegate back to its original (parent) reference.  
7.         // this behavior emulates a stack of delegates without actually necessitating one.  
8.         BeanDefinitionParserDelegate parent = this.delegate;  
9.         this.delegate = createDelegate(getReaderContext(), root, parent);  
10.   
11.         if (this.delegate.isDefaultNamespace(root)) {  
12.             String profileSpec = root.getAttribute(PROFILE_ATTRIBUTE);  
13.             if (StringUtils.hasText(profileSpec)) {  
14.                 String[] specifiedProfiles = StringUtils.tokenizeToStringArray(  
15.                         profileSpec, BeanDefinitionParserDelegate.MULTI_VALUE_ATTRIBUTE_DELIMITERS);  
16.                 if (!getReaderContext().getEnvironment().acceptsProfiles(specifiedProfiles)) {  
17.                     return;  
18.                 }  
19.             }  
20.         }  
21.   
22.         preProcessXml(root);  
23.         parseBeanDefinitions(root, this.delegate);  
24.         postProcessXml(root);  
25.   
26.         this.delegate = parent;  
27.     }  

1. protected void doRegisterBeanDefinitions(Element root) {

2. // Any nested elements will cause recursion in this method. In

3. // order to propagate and preserve default-* attributes correctly,

4. // keep track of the current (parent) delegate, which may be null. Create

5. // the new (child) delegate with a reference to the parent for fallback purposes,

6. // then ultimately reset this.delegate back to its original (parent) reference.

7. // this behavior emulates a stack of delegates without actually necessitating one.

8. BeanDefinitionParserDelegate parent = this.delegate;

9. this.delegate = createDelegate(getReaderContext(), root, parent);

11. if (this.delegate.isDefaultNamespace(root)) {

12. String profileSpec = root.getAttribute(PROFILE_ATTRIBUTE);

13. if (StringUtils.hasText(profileSpec)) {

14. String[] specifiedProfiles = StringUtils.tokenizeToStringArray(

15. profileSpec, BeanDefinitionParserDelegate.MULTI_VALUE_ATTRIBUTE_DELIMITERS);

16. if (!getReaderContext().getEnvironment().acceptsProfiles(specifiedProfiles)) {

17. return;

18. }

19. }

20. }

22. preProcessXml(root);

23. parseBeanDefinitions(root, this.delegate);

24. postProcessXml(root);

26. this.delegate = parent;

27. }

2.3.3 parseBeanDefinitions

从document对象的根节点开始，依据不同类型解析。具体调用parseDefaultElement和parseCustomElement两个方法进行解析。这个主要的区别是因为bean的命名空间可能不同，Spring的默认命名空间是“http://www.springframework.org/schema/beans”，如果不是这个命名空间中定义的bean，将使用parseCustomElement方法。

[java] view plain copy

1. protected void parseBeanDefinitions(Element root, BeanDefinitionParserDelegate delegate) {  
2.         if (delegate.isDefaultNamespace(root)) {  
3.             NodeList nl = root.getChildNodes();  
4.             for (int i = 0; i < nl.getLength(); i++) {  
5.                 Node node = nl.item(i);  
6.                 if (node instanceof Element) {  
7.                     Element ele = (Element) node;  
8.                     if (delegate.isDefaultNamespace(ele)) {  
9.                         parseDefaultElement(ele, delegate);  
10.                     }  
11.                     else {  
12.                         delegate.parseCustomElement(ele);  
13.                     }  
14.                 }  
15.             }  
16.         }  
17.         else {  
18.             delegate.parseCustomElement(root);  
19.         }  
20.     }  

1. protected void parseBeanDefinitions(Element root, BeanDefinitionParserDelegate delegate) {

2. if (delegate.isDefaultNamespace(root)) {

3. NodeList nl = root.getChildNodes();

4. for (int i = 0; i < nl.getLength(); i++) {

5. Node node = nl.item(i);

6. if (node instanceof Element) {

7. Element ele = (Element) node;

8. if (delegate.isDefaultNamespace(ele)) {

9. parseDefaultElement(ele, delegate);

10. }

11. else {

12. delegate.parseCustomElement(ele);

13. }

14. }

15. }

16. }

17. else {

18. delegate.parseCustomElement(root);

19. }

20. }

2.3.4 parseDefaultElement

这个方法就是根据bean的类型进行不同的方法解析。

[java] view plain copy

1. private void parseDefaultElement(Element ele, BeanDefinitionParserDelegate delegate) {  
2.         //解析import  
3.         if (delegate.nodeNameEquals(ele, IMPORT_ELEMENT)) {  
4.             importBeanDefinitionResource(ele);  
5.         }  
6.         //解析alias  
7.         else if (delegate.nodeNameEquals(ele, ALIAS_ELEMENT)) {  
8.             processAliasRegistration(ele);  
9.         }  
10.         //解析普通的bean  
11.         else if (delegate.nodeNameEquals(ele, BEAN_ELEMENT)) {  
12.             processBeanDefinition(ele, delegate);  
13.         }  
14.         //解析beans  递归返回  
15.         else if (delegate.nodeNameEquals(ele, NESTED_BEANS_ELEMENT)) {  
16.             // recurse  
17.             doRegisterBeanDefinitions(ele);  
18.         }  
19.     }  

1. private void parseDefaultElement(Element ele, BeanDefinitionParserDelegate delegate) {

2. //解析import

3. if (delegate.nodeNameEquals(ele, IMPORT_ELEMENT)) {

4. importBeanDefinitionResource(ele);

5. }

6. //解析alias

7. else if (delegate.nodeNameEquals(ele, ALIAS_ELEMENT)) {

8. processAliasRegistration(ele);

9. }

10. //解析普通的bean

11. else if (delegate.nodeNameEquals(ele, BEAN_ELEMENT)) {

12. processBeanDefinition(ele, delegate);

13. }

14. //解析beans 递归返回

15. else if (delegate.nodeNameEquals(ele, NESTED_BEANS_ELEMENT)) {

16. // recurse

17. doRegisterBeanDefinitions(ele);

18. }

19. }

2.3.5 processBeanDefinition

这个方法完成对普通，也是最常见的Bean的解析。这个方法实际上完成了解析和注册两个过程。这两个过程分别向下调用parseBeanDefinitionElement和registerBeanDefinition方法。

[java] view plain copy

1. protected void processBeanDefinition(Element ele, BeanDefinitionParserDelegate delegate) {  
2.         //定义BeanDefinitionHolder对象 ，完成解析的对象存放在这个对象里面  
3.         BeanDefinitionHolder bdHolder = delegate.parseBeanDefinitionElement(ele);  
4.         if (bdHolder != null) {  
5.             bdHolder = delegate.decorateBeanDefinitionIfRequired(ele, bdHolder);  
6.             try {  
7.                 // 向容器注册解析完成的Bean  
8.                 BeanDefinitionReaderUtils.registerBeanDefinition(bdHolder, getReaderContext().getRegistry());  
9.             }  
10.             catch (BeanDefinitionStoreException ex) {  
11.                 getReaderContext().error("Failed to register bean definition with name '" +  
12.                         bdHolder.getBeanName() + "'", ele, ex);  
13.             }  
14.             // Send registration event.  
15.             getReaderContext().fireComponentRegistered(new BeanComponentDefinition(bdHolder));  
16.         }  
17.     }  
18.       

1. protected void processBeanDefinition(Element ele, BeanDefinitionParserDelegate delegate) {

2. //定义BeanDefinitionHolder对象 ，完成解析的对象存放在这个对象里面

3. BeanDefinitionHolder bdHolder = delegate.parseBeanDefinitionElement(ele);

4. if (bdHolder != null) {

5. bdHolder = delegate.decorateBeanDefinitionIfRequired(ele, bdHolder);

6. try {

7. // 向容器注册解析完成的Bean

8. BeanDefinitionReaderUtils.registerBeanDefinition(bdHolder, getReaderContext().getRegistry());

9. }

10. catch (BeanDefinitionStoreException ex) {

11. getReaderContext().error("Failed to register bean definition with name '" +

12. bdHolder.getBeanName() + "'", ele, ex);

13. }

14. // Send registration event.

15. getReaderContext().fireComponentRegistered(new BeanComponentDefinition(bdHolder));

16. }

17. }

2.3.6 parseBeanDefinitionElement

定义在BeanDefinitionParserDelegate 类中，完成了BeanDefition解析工作。在这里可以看到，AbstractBeanDefinition实际上spring的内部保存的数据结构

[java] view plain copy

1. public BeanDefinitionHolder parseBeanDefinitionElement(Element ele, BeanDefinition containingBean) {  
2.         String id = ele.getAttribute(ID_ATTRIBUTE);  
3.         String nameAttr = ele.getAttribute(NAME_ATTRIBUTE);  
4.   
5.         List aliases = new ArrayList();  
6.         if (StringUtils.hasLength(nameAttr)) {  
7.             String[] nameArr = StringUtils.tokenizeToStringArray(nameAttr, MULTI_VALUE_ATTRIBUTE_DELIMITERS);  
8.             aliases.addAll(Arrays.asList(nameArr));  
9.         }  
10.   
11.         String beanName = id;  
12.         if (!StringUtils.hasText(beanName) && !aliases.isEmpty()) {  
13.             beanName = aliases.remove(0);  
14.             if (logger.isDebugEnabled()) {  
15.                 logger.debug("No XML 'id' specified - using '" + beanName +  
16.                         "' as bean name and " + aliases + " as aliases");  
17.             }  
18.         }  
19.   
20.         if (containingBean == null) {  
21.             checkNameUniqueness(beanName, aliases, ele);  
22.         }  
23.   
24.         AbstractBeanDefinition beanDefinition = parseBeanDefinitionElement(ele, beanName, containingBean);  
25.         if (beanDefinition != null) {  
26.             if (!StringUtils.hasText(beanName)) {  
27.                 try {  
28.                     if (containingBean != null) {  
29.                         beanName = BeanDefinitionReaderUtils.generateBeanName(  
30.                                 beanDefinition, this.readerContext.getRegistry(), true);  
31.                     }  
32.                     else {  
33.                         beanName = this.readerContext.generateBeanName(beanDefinition);  
34.                         // Register an alias for the plain bean class name, if still possible,  
35.                         // if the generator returned the class name plus a suffix.  
36.                         // This is expected for Spring 1.2/2.0 backwards compatibility.  
37.                         String beanClassName = beanDefinition.getBeanClassName();  
38.                         if (beanClassName != null &&  
39.                                 beanName.startsWith(beanClassName) && beanName.length() > beanClassName.length() &&  
40.                                 !this.readerContext.getRegistry().isBeanNameInUse(beanClassName)) {  
41.                             aliases.add(beanClassName);  
42.                         }  
43.                     }  
44.                     if (logger.isDebugEnabled()) {  
45.                         logger.debug("Neither XML 'id' nor 'name' specified - " +  
46.                                 "using generated bean name [" + beanName + "]");  
47.                     }  
48.                 }  
49.                 catch (Exception ex) {  
50.                     error(ex.getMessage(), ele);  
51.                     return null;  
52.                 }  
53.             }  
54.             String[] aliasesArray = StringUtils.toStringArray(aliases);  
55.             return new BeanDefinitionHolder(beanDefinition, beanName, aliasesArray);  
56.         }  
57.   
58.         return null;  
59.     }  

1. public BeanDefinitionHolder parseBeanDefinitionElement(Element ele, BeanDefinition containingBean) {

2. String id = ele.getAttribute(ID_ATTRIBUTE);

3. String nameAttr = ele.getAttribute(NAME_ATTRIBUTE);

5. List aliases = new ArrayList();

6. if (StringUtils.hasLength(nameAttr)) {

7. String[] nameArr = StringUtils.tokenizeToStringArray(nameAttr, MULTI_VALUE_ATTRIBUTE_DELIMITERS);

8. aliases.addAll(Arrays.asList(nameArr));

9. }

11. String beanName = id;

12. if (!StringUtils.hasText(beanName) && !aliases.isEmpty()) {

13. beanName = aliases.remove(0);

14. if (logger.isDebugEnabled()) {

15. logger.debug("No XML 'id' specified - using '" + beanName +

16. "' as bean name and " + aliases + " as aliases");

17. }

18. }

20. if (containingBean == null) {

21. checkNameUniqueness(beanName, aliases, ele);

22. }

24. AbstractBeanDefinition beanDefinition = parseBeanDefinitionElement(ele, beanName, containingBean);

25. if (beanDefinition != null) {

26. if (!StringUtils.hasText(beanName)) {

27. try {

28. if (containingBean != null) {

29. beanName = BeanDefinitionReaderUtils.generateBeanName(

30. beanDefinition, this.readerContext.getRegistry(), true);

31. }

32. else {

33. beanName = this.readerContext.generateBeanName(beanDefinition);

34. // Register an alias for the plain bean class name, if still possible,

35. // if the generator returned the class name plus a suffix.

36. // This is expected for Spring 1.2/2.0 backwards compatibility.

37. String beanClassName = beanDefinition.getBeanClassName();

38. if (beanClassName != null &&

39. beanName.startsWith(beanClassName) && beanName.length() > beanClassName.length() &&

40. !this.readerContext.getRegistry().isBeanNameInUse(beanClassName)) {

41. aliases.add(beanClassName);

42. }

43. }

44. if (logger.isDebugEnabled()) {

45. logger.debug("Neither XML 'id' nor 'name' specified - " +

46. "using generated bean name [" + beanName + "]");

47. }

48. }

49. catch (Exception ex) {

50. error(ex.getMessage(), ele);

51. return null;

52. }

53. }

54. String[] aliasesArray = StringUtils.toStringArray(aliases);

55. return new BeanDefinitionHolder(beanDefinition, beanName, aliasesArray);

56. }

58. return null;

59. }

[java] view plain copy

1. /** 
2.      * Parse the bean definition itself, without regard to name or aliases. May return 
3.      * {@code null} if problems occurred during the parsing of the bean definition. 
4.      */  
5.     public AbstractBeanDefinition parseBeanDefinitionElement(  
6.             Element ele, String beanName, BeanDefinition containingBean) {  
7.   
8.         this.parseState.push(new BeanEntry(beanName));  
9.   
10.         String className = null;  
11.         if (ele.hasAttribute(CLASS_ATTRIBUTE)) {  
12.             className = ele.getAttribute(CLASS_ATTRIBUTE).trim();  
13.         }  
14.   
15.         try {  
16.             String parent = null;  
17.             if (ele.hasAttribute(PARENT_ATTRIBUTE)) {  
18.                 parent = ele.getAttribute(PARENT_ATTRIBUTE);  
19.             }  
20.             AbstractBeanDefinition bd = createBeanDefinition(className, parent);  
21.   
22.             parseBeanDefinitionAttributes(ele, beanName, containingBean, bd);  
23.             bd.setDescription(DomUtils.getChildElementValueByTagName(ele, DESCRIPTION_ELEMENT));  
24.   
25.             parseMetaElements(ele, bd);  
26.             parseLookupOverrideSubElements(ele, bd.getMethodOverrides());  
27.             parseReplacedMethodSubElements(ele, bd.getMethodOverrides());  
28.   
29.             parseConstructorArgElements(ele, bd);  
30.             parsePropertyElements(ele, bd);  
31.             parseQualifierElements(ele, bd);  
32.   
33.             bd.setResource(this.readerContext.getResource());  
34.             bd.setSource(extractSource(ele));  
35.   
36.             return bd;  
37.         }  
38.         catch (ClassNotFoundException ex) {  
39.             error("Bean class [" + className + "] not found", ele, ex);  
40.         }  
41.         catch (NoClassDefFoundError err) {  
42.             error("Class that bean class [" + className + "] depends on not found", ele, err);  
43.         }  
44.         catch (Throwable ex) {  
45.             error("Unexpected failure during bean definition parsing", ele, ex);  
46.         }  
47.         finally {  
48.             this.parseState.pop();  
49.         }  
50.   
51.         return null;  
52.     }  

1. /**

2. * Parse the bean definition itself, without regard to name or aliases. May return

3. * {@code null} if problems occurred during the parsing of the bean definition.

4. */

5. public AbstractBeanDefinition parseBeanDefinitionElement(

6. Element ele, String beanName, BeanDefinition containingBean) {

8. this.parseState.push(new BeanEntry(beanName));

10. String className = null;

11. if (ele.hasAttribute(CLASS_ATTRIBUTE)) {

12. className = ele.getAttribute(CLASS_ATTRIBUTE).trim();

13. }

15. try {

16. String parent = null;

17. if (ele.hasAttribute(PARENT_ATTRIBUTE)) {

18. parent = ele.getAttribute(PARENT_ATTRIBUTE);

19. }

20. AbstractBeanDefinition bd = createBeanDefinition(className, parent);

22. parseBeanDefinitionAttributes(ele, beanName, containingBean, bd);

23. bd.setDescription(DomUtils.getChildElementValueByTagName(ele, DESCRIPTION_ELEMENT));

25. parseMetaElements(ele, bd);

26. parseLookupOverrideSubElements(ele, bd.getMethodOverrides());

27. parseReplacedMethodSubElements(ele, bd.getMethodOverrides());

29. parseConstructorArgElements(ele, bd);

30. parsePropertyElements(ele, bd);

31. parseQualifierElements(ele, bd);

33. bd.setResource(this.readerContext.getResource());

34. bd.setSource(extractSource(ele));

36. return bd;

37. }

38. catch (ClassNotFoundException ex) {

39. error("Bean class [" + className + "] not found", ele, ex);

40. }

41. catch (NoClassDefFoundError err) {

42. error("Class that bean class [" + className + "] depends on not found", ele, err);

43. }

44. catch (Throwable ex) {

45. error("Unexpected failure during bean definition parsing", ele, ex);

46. }

47. finally {

48. this.parseState.pop();

49. }

51. return null;

52. }

2.4 注册BeanDefition

完成了上面的三步后，目前ApplicationContext中有两种类型的结构，一个是DefaultListableBeanFactory，它是Spring IOC容器，另一种是若干个BeanDefinitionHolder，这里面包含实际的Bean对象，AbstractBeanDefition。

需要把二者关联起来，这样Spring才能对Bean进行管理。在DefaultListableBeanFactory中定义了一个Map对象，保存所有的BeanDefition。这个注册的过程就是把前面解析得到的Bean放入这个Map的过程。

[java] view plain copy

1. /** Map of bean definition objects, keyed by bean name */  
2.     private final Map beanDefinitionMap = new ConcurrentHashMap(64);  

1. /** Map of bean definition objects, keyed by bean name */

2.     private final Map beanDefinitionMap = new ConcurrentHashMap(64);

2.4.1 registerBeanDefinition

注册的入口，对于普通的Bean和Alias调用不同类型的注册方法进行注册。

[java] view plain copy

1. public static void registerBeanDefinition(  
2.             BeanDefinitionHolder definitionHolder, BeanDefinitionRegistry registry)  
3.             throws BeanDefinitionStoreException {  
4.   
5.         // Register bean definition under primary name.  
6.         String beanName = definitionHolder.getBeanName();  
7.         registry.registerBeanDefinition(beanName, definitionHolder.getBeanDefinition());  
8.   
9.         // Register aliases for bean name, if any.  
10.         String[] aliases = definitionHolder.getAliases();  
11.         if (aliases != null) {  
12.             for (String alias : aliases) {  
13.                 registry.registerAlias(beanName, alias);  
14.             }  
15.         }  
16.     }  

1. public static void registerBeanDefinition(

2. BeanDefinitionHolder definitionHolder, BeanDefinitionRegistry registry)

3. throws BeanDefinitionStoreException {

5. // Register bean definition under primary name.

6. String beanName = definitionHolder.getBeanName();

7. registry.registerBeanDefinition(beanName, definitionHolder.getBeanDefinition());

9. // Register aliases for bean name, if any.

10. String[] aliases = definitionHolder.getAliases();

11. if (aliases != null) {

12. for (String alias : aliases) {

13. registry.registerAlias(beanName, alias);

14. }

15. }

16. }

2.4.2 registerBeanDefinition

注册Bean 定义在DefaultListableBeanFactory中

[java] view plain copy

1. public void registerBeanDefinition(String beanName, BeanDefinition beanDefinition)  
2.             throws BeanDefinitionStoreException {  
3.         //非空断言  
4.         Assert.hasText(beanName, "Bean name must not be empty");  
5.         Assert.notNull(beanDefinition, "BeanDefinition must not be null");  
6.   
7.         if (beanDefinition instanceof AbstractBeanDefinition) {  
8.             try {  
9.                 ((AbstractBeanDefinition) beanDefinition).validate();  
10.             }  
11.             catch (BeanDefinitionValidationException ex) {  
12.                 throw new BeanDefinitionStoreException(beanDefinition.getResourceDescription(), beanName,  
13.                         "Validation of bean definition failed", ex);  
14.             }  
15.         }  
16.   
17.         BeanDefinition oldBeanDefinition;  
18.   
19.         oldBeanDefinition = this.beanDefinitionMap.get(beanName);  
20.         //同名检测  
21.         if (oldBeanDefinition != null) {  
22.             //是否能够覆盖检测  
23.             if (!this.allowBeanDefinitionOverriding) {  
24.                 throw new BeanDefinitionStoreException(beanDefinition.getResourceDescription(), beanName,  
25.                         "Cannot register bean definition [" + beanDefinition + "] for bean '" + beanName +  
26.                         "': There is already [" + oldBeanDefinition + "] bound.");  
27.             }  
28.             else if (oldBeanDefinition.getRole() < beanDefinition.getRole()) {  
29.                 // e.g. was ROLE_APPLICATION, now overriding with ROLE_SUPPORT or ROLE_INFRASTRUCTURE  
30.                 if (this.logger.isWarnEnabled()) {  
31.                     this.logger.warn("Overriding user-defined bean definition for bean '" + beanName +  
32.                             " with a framework-generated bean definition ': replacing [" +  
33.                             oldBeanDefinition + "] with [" + beanDefinition + "]");  
34.                 }  
35.             }  
36.             else {  
37.                 if (this.logger.isInfoEnabled()) {  
38.                     this.logger.info("Overriding bean definition for bean '" + beanName +  
39.                             "': replacing [" + oldBeanDefinition + "] with [" + beanDefinition + "]");  
40.                 }  
41.             }  
42.         }  
43.         else {  
44.             this.beanDefinitionNames.add(beanName);  
45.             this.manualSingletonNames.remove(beanName);  
46.             this.frozenBeanDefinitionNames = null;  
47.         }  
48.         //放入Map中  
49.         this.beanDefinitionMap.put(beanName, beanDefinition);  
50.   
51.         if (oldBeanDefinition != null || containsSingleton(beanName)) {  
52.             resetBeanDefinition(beanName);  
53.         }  
54.     }  

1. public void registerBeanDefinition(String beanName, BeanDefinition beanDefinition)

2. throws BeanDefinitionStoreException {

3. //非空断言

4. Assert.hasText(beanName, "Bean name must not be empty");

5. Assert.notNull(beanDefinition, "BeanDefinition must not be null");

7. if (beanDefinition instanceof AbstractBeanDefinition) {

8. try {

9. ((AbstractBeanDefinition) beanDefinition).validate();

10. }

11. catch (BeanDefinitionValidationException ex) {

12. throw new BeanDefinitionStoreException(beanDefinition.getResourceDescription(), beanName,

13. "Validation of bean definition failed", ex);

14. }

15. }

17. BeanDefinition oldBeanDefinition;

19. oldBeanDefinition = this.beanDefinitionMap.get(beanName);

20. //同名检测

21. if (oldBeanDefinition != null) {

22. //是否能够覆盖检测

23. if (!this.allowBeanDefinitionOverriding) {

24. throw new BeanDefinitionStoreException(beanDefinition.getResourceDescription(), beanName,

25. "Cannot register bean definition [" + beanDefinition + "] for bean '" + beanName +

26. "': There is already [" + oldBeanDefinition + "] bound.");

27. }

28. else if (oldBeanDefinition.getRole() < beanDefinition.getRole()) {

29. // e.g. was ROLE_APPLICATION, now overriding with ROLE_SUPPORT or ROLE_INFRASTRUCTURE

30. if (this.logger.isWarnEnabled()) {

31. this.logger.warn("Overriding user-defined bean definition for bean '" + beanName +

32. " with a framework-generated bean definition ': replacing [" +

33. oldBeanDefinition + "] with [" + beanDefinition + "]");

34. }

35. }

36. else {

37. if (this.logger.isInfoEnabled()) {

38. this.logger.info("Overriding bean definition for bean '" + beanName +

39. "': replacing [" + oldBeanDefinition + "] with [" + beanDefinition + "]");

40. }

41. }

42. }

43. else {

44. this.beanDefinitionNames.add(beanName);

45. this.manualSingletonNames.remove(beanName);

46. this.frozenBeanDefinitionNames = null;

47. }

48. //放入Map中

49. this.beanDefinitionMap.put(beanName, beanDefinition);

51. if (oldBeanDefinition != null || containsSingleton(beanName)) {

52. resetBeanDefinition(beanName);

53. }

54. }

2.4.3 registerAlias

定义在SimpleAliasRegistry类，对别名进行注册

[java] view plain copy

1. public void registerAlias(String name, String alias) {  
2.         Assert.hasText(name, "'name' must not be empty");  
3.         Assert.hasText(alias, "'alias' must not be empty");  
4.         if (alias.equals(name)) {  
5.             this.aliasMap.remove(alias);  
6.         }  
7.         else {  
8.             if (!allowAliasOverriding()) {  
9.                 String registeredName = this.aliasMap.get(alias);  
10.                 if (registeredName != null && !registeredName.equals(name)) {  
11.                     throw new IllegalStateException("Cannot register alias '" + alias + "' for name '" +  
12.                             name + "': It is already registered for name '" + registeredName + "'.");  
13.                 }  
14.             }  
15.             checkForAliasCircle(name, alias);  
16.             this.aliasMap.put(alias, name);  
17.         }  
18.     }  

1. public void registerAlias(String name, String alias) {

2. Assert.hasText(name, "'name' must not be empty");

3. Assert.hasText(alias, "'alias' must not be empty");

4. if (alias.equals(name)) {

5. this.aliasMap.remove(alias);

6. }

7. else {

8. if (!allowAliasOverriding()) {

9. String registeredName = this.aliasMap.get(alias);

10. if (registeredName != null && !registeredName.equals(name)) {

11. throw new IllegalStateException("Cannot register alias '" + alias + "' for name '" +

12. name + "': It is already registered for name '" + registeredName + "'.");

13. }

14. }

15. checkForAliasCircle(name, alias);

16. this.aliasMap.put(alias, name);

17. }

18. }