Spring源码学习IOC(7)：浅析aware相关接口

spring中 有一大堆Aware结尾接口,  例如BeanFactoryAware,  ApplicationContextAware, ServletContextAware等

 在程序中 我们自定义的bean实现了 Aware相关接口  spring 通过回调   就可以获得一些资源  

 比如说 我们的bean实现BeanFactoryAware  spring会在bean实例化(getBean)阶段 回调该setBeanFactory方法   注入BeanFactory实例(也就是this)   

 spring   BeanFactoryAware 接口定义

[java]  view plain copy print ?

1. public interface BeanFactoryAware {  
2.   
3.    void setBeanFactory(BeanFactory beanFactory) throws BeansException;  
4.   
5. }  

 spring容器中的bean 实例化 是在AbstractBeanFactory getBean中发生

[java]  view plain copy print ?

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

调用的 doGetBean 方法比较复杂  简单看看 创建单例这段

[java]  view plain copy print ?

1. protected Object doGetBean(  
2.             final String name, final Class requiredType, final Object[] args, boolean typeCheckOnly) throws BeansException {  
3.   
4.         final String beanName = transformedBeanName(name);  
5.             .................略          // Create bean instance.  
6.             //bean的定义是不是单例   
7.             if (mbd.isSingleton()) {  
8.                 sharedInstance = getSingleton(beanName, new ObjectFactory() {  
9.                     public Object getObject() throws BeansException {  
10.                         try {  
11.                             // 是一个抽象方法  在子类AbstractAutowireCapableBeanFactory中实现  
12.                             return createBean(beanName, mbd, args);  
13.                         }  
14.                         catch (BeansException ex) {  
15.                             destroySingleton(beanName);  
16.                             throw ex;  
17.                         }  
18.                     }  
19.                 });  
20.                 bean = getObjectForBeanInstance(sharedInstance, name, beanName, mbd);  
21.             }  
22.   
23.         .................略  
24.         return bean;  
25.     }  

AbstractAutowireCapableBeanFactory  createBean方法

[java]  view plain copy print ?

1. protected Object createBean(final String beanName, final RootBeanDefinition mbd, final Object[] args)  
2.         throws BeanCreationException {  
3.   
4.     AccessControlContext acc = AccessController.getContext();  
5.     return AccessController.doPrivileged(new PrivilegedAction() {  
6.         public Object run() {  
7.             .................略  
8.             //关注doCreateBean方法  
9.             Object beanInstance = doCreateBean(beanName, mbd, args);  
10.             if (logger.isDebugEnabled()) {  
11.                 logger.debug("Finished creating instance of bean '" + beanName + "'");  
12.             }  
13.             return beanInstance;  
14.         }  
15.     }, acc);  
16. }  

doCreateBean方法

[java]  view plain copy print ?

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.             //实现 *Aware部分接口， InitializingBean接口  方法调用在此发生  
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.                 throw new BeanCreationException(mbd.getResourceDescription(), beanName, "Initialization of bean failed", ex);  
21.             }  
22.         }  
23.   
24.         .................略  
25.         return exposedObject;  
26. }  

initializeBean方法

[java]  view plain copy print ?

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.     // 如果当前bean 是BeanFactoryAware的一个实例   
9.     if (bean instanceof BeanFactoryAware) {  
10.         //回调当前实例注入资源  
11.         ((BeanFactoryAware) bean).setBeanFactory(this);  
12.     }  
13.   
14.     Object wrappedBean = bean;  
15.     if (mbd == null || !mbd.isSynthetic()) {  
16.         //BeanPostProcessor 接口  postProcessBeforeInitialization方法回调  
17.         wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);  
18.     }  
19.     try {  
20.         // 实现InitializingBean接口  afterPropertiesSet方法调用  
21.         invokeInitMethods(beanName, wrappedBean, mbd);  
22.     }  
23.     catch (Throwable ex) {  
24.         throw new BeanCreationException(  
25.                 (mbd != null ? mbd.getResourceDescription() : null),  
26.                 beanName, "Invocation of init method failed", ex);  
27.     }  
28.   
29.     if (mbd == null || !mbd.isSynthetic()) {  
30.         wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);  
31.     }  
32.     return wrappedBean;  
33. }  

Spring  aware相关接口