spring中 有一大堆Aware結尾介面,  例如BeanFactoryAware,  ApplicationContextAware, ServletContextAware等

 在程式中 我們自定義的bean實現了 Aware相關介面  spring 通過回撥   就可以獲得一些資源  

 比如說 我們的bean實現BeanFactoryAware  spring會在bean例項化(getBean)階段 回撥該setBeanFactory方法   注入BeanFactory例項(也就是this)   

 spring   BeanFactoryAware 介面定義

1. publicinterface BeanFactoryAware {  
2.    void setBeanFactory(BeanFactory beanFactory) throws BeansException;  
3. }  

 spring容器中的bean 例項化 是在AbstractBeanFactory getBean中發生

1. public Object getBean(String name, Class requiredType, Object[] args) 
   throws BeansException {  
2.     return doGetBean(name, requiredType, args, false);  
3. }  

呼叫的 doGetBean 方法比較複雜  簡單看看 建立單例這段

1. protected Object doGetBean(  
2.             final String name, final Class requiredType, final Object[] args, boolean typeCheckOnly) throws BeansException {  
3.         final String beanName = transformedBeanName(name);  
4.             .................略          // Create bean instance.
5.             //bean的定義是不是單例 
6.             if (mbd.isSingleton()) {  
7.                 sharedInstance = getSingleton(beanName, new ObjectFactory() {  
8.                     public Object getObject() throws BeansException {  
9.                         try {  
10.                             // 是一個抽象方法  在子類AbstractAutowireCapableBeanFactory中實現
11.                             return createBean(beanName, mbd, args);  
12.                         }  
13.                         catch (BeansException ex) {  
14.                             destroySingleton(beanName);  
15.                             throw ex;  
16.                         }  
17.                     }  
18.                 });  
19.                 bean = getObjectForBeanInstance(sharedInstance, name, beanName, mbd);  
20.             }  
21.         .................略  
22.         return bean;  
23.     }  

AbstractAutowireCapableBeanFactory  createBean方法

1. protected Object createBean(final String beanName, final RootBeanDefinition mbd, final Object[] args)  
2.         throws BeanCreationException {  
3.     AccessControlContext acc = AccessController.getContext();  
4.     return AccessController.doPrivileged(new PrivilegedAction() {  
5.         public Object run() {  
6.             .................略  
7.             //關注doCreateBean方法
8.             Object beanInstance = doCreateBean(beanName, mbd, args);  
9.             if (logger.isDebugEnabled()) {  
10.                 logger.debug("Finished creating instance of bean '" + beanName + "'");  
11.             }  
12.             return beanInstance;  
13.         }  
14.     }, acc);  
15. }  

doCreateBean方法

1. protected Object doCreateBean(final String beanName, final RootBeanDefinition mbd, final Object[] args) {  
2.         // Instantiate the bean.
3.         BeanWrapper instanceWrapper = null;  
4.         if (mbd.isSingleton()) {  
5.             instanceWrapper = (BeanWrapper) this.factoryBeanInstanceCache.remove(beanName);  
6.         }  
7.         .................略  
8.         // Initialize the bean instance.
9.         Object exposedObject = bean;  
10.         try {  
11.             populateBean(beanName, mbd, instanceWrapper);  
12.             //實現 *Aware部分介面， InitializingBean介面  方法呼叫在此發生
13.             exposedObject = initializeBean(beanName, exposedObject, mbd);  
14.         }  
15.         catch (Throwable ex) {  
16.             if (ex instanceof BeanCreationException && beanName.equals(((BeanCreationException) ex).getBeanName())) {  
17.                 throw (BeanCreationException) ex;  
18.             }  
19.             else {  
20.                 thrownew BeanCreationException(mbd.getResourceDescription(), beanName, "Initialization of bean failed", ex);  
21.             }  
22.         }  
23.         .................略  
24.         return exposedObject;  
25. }  

initializeBean方法

1. protected Object initializeBean(String beanName, Object bean, RootBeanDefinition mbd) {  
2.     if (bean instanceof BeanNameAware) {  
3.         ((BeanNameAware) bean).setBeanName(beanName);  
4.     }  
5.     if (bean instanceof BeanClassLoaderAware) {  
6.         ((BeanClassLoaderAware) bean).setBeanClassLoader(getBeanClassLoader());  
7.     }  
8.     // 如果當前bean 是BeanFactoryAware的一個例項 
9.     if (bean instanceof BeanFactoryAware) {  
10.         //回調當前例項注入資源
11.         ((BeanFactoryAware) bean).setBeanFactory(this);  
12.     }  
13.     Object wrappedBean = bean;  
14.     if (mbd == null || !mbd.isSynthetic()) {  
15.         //BeanPostProcessor 介面  postProcessBeforeInitialization方法回撥
16.         wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);  
17.     }  
18.     try {  
19.         // 實現InitializingBean介面  afterPropertiesSet方法呼叫
20.         invokeInitMethods(beanName, wrappedBean, mbd);  
21.     }  
22.     catch (Throwable ex) {  
23.         thrownew BeanCreationException(  
24.                 (mbd != null ? mbd.getResourceDescription() : null),  
25.                 beanName, "Invocation of init method failed", ex);  
26.     }  
27.     if (mbd == null || !mbd.isSynthetic()) {  
28.         wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);  
29.     }  
30.     return wrappedBean;  
31. }  

Spring  aware相關介面