spring之InitializingBean接口的使用

//记录几个spring的接口以及使用
//从名字可以看出来这个接口主要用于初始化bean用。在bean被初始化后就会执行afterPropertiesSet方法。
public interface InitializingBean {

 void afterPropertiesSet() throws Exception;

}

//其实现原理如下该方法在AbstractAutowireCapableBeanFactory中
protected void invokeInitMethods(String beanName, final Object bean, RootBeanDefinition mbd)
			throws Throwable {
                //判断是否实现了InitializingBean接口
		boolean isInitializingBean = (bean instanceof InitializingBean);
		if (isInitializingBean && (mbd == null || !mbd.isExternallyManagedInitMethod("afterPropertiesSet"))) {
			if (logger.isDebugEnabled()) {
				logger.debug("Invoking afterPropertiesSet() on bean with name '" + beanName + "'");
			}
			if (System.getSecurityManager() != null) {
				try {
					AccessController.doPrivileged(new PrivilegedExceptionAction<Object>() {
						@Override
						public Object run() throws Exception {
						//执行afterPropertiesSet
							((InitializingBean) bean).afterPropertiesSet();
							return null;
						}
					}, getAccessControlContext());
				}
				catch (PrivilegedActionException pae) {
					throw pae.getException();
				}
			}
			else {
			        //执行afterPropertiesSet
				((InitializingBean) bean).afterPropertiesSet();
			}
		}

		if (mbd != null) {
			String initMethodName = mbd.getInitMethodName();
			if (initMethodName != null && !(isInitializingBean && "afterPropertiesSet".equals(initMethodName)) &&
					!mbd.isExternallyManagedInitMethod(initMethodName)) {
				invokeCustomInitMethod(beanName, bean, mbd);
			}
		}
	}

/**
所以我们在写框架的时候如果要进行一些初始化工作就可以实现InitializingBean接口。
*/