Spring中常用重要的接口

Spring (ApplicationContext 初始化Bean的方法 refresh())

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.//创建Bean并post等方法
				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) {
				// Destroy already created singletons to avoid dangling resources.
				destroyBeans();

				// Reset 'active' flag.
				cancelRefresh(ex);

				// Propagate exception to caller.
				throw ex;
			}
		}
	}

　　

Spring 框架中想自己在bean的初始化阶段自定义一些逻辑，或者想获取一些资源，非常有用的接口有

BeanPostProcessor,// properties 设置完成，InitializingBean的 afterPropertiesSet()， init-method完成后对bean进行一些逻辑处理

InitializingBean,// 提供afterPropertiesSet()，位于init-method之前调用（这两方法都可用于实现bean init方法）；

DestructionAwareBeanPostProcessor,//postProcessBeforeDestruction(Object bean, String beanName) 方法于 destory方法之前调用；

BeanFactoryAware // setBeanFactory(BeanFactory beanFactory) 接口使Bean初始化完成后获取BeanFactory资源，以便操作。类似的还有ApplicationContextAware....

public interface BeanPostProcessor {

    /**property values已经设置完成，
     * Apply this BeanPostProcessor to the given new bean instance <i>before</i> any bean
     * initialization callbacks (like InitializingBean's <code>afterPropertiesSet</code>
     * or a custom init-method). The bean will already be populated with property values.
     * The returned bean instance may be a wrapper around the original.
     * @param bean the new bean instance
     * @param beanName the name of the bean
     * @return the bean instance to use, either the original or a wrapped one; if
     * <code>null</code>, no subsequent BeanPostProcessors will be invoked
     * @throws org.springframework.beans.BeansException in case of errors
     * @see org.springframework.beans.factory.InitializingBean#afterPropertiesSet
     */
    Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException;

    /**
     * Apply this BeanPostProcessor to the given new bean instance <i>after</i> any bean
     * initialization callbacks (like InitializingBean's <code>afterPropertiesSet</code>
     * or a custom init-method). The bean will already be populated with property values.
     * The returned bean instance may be a wrapper around the original.
     * <p>In case of a FactoryBean, this callback will be invoked for both the FactoryBean
     * instance and the objects created by the FactoryBean (as of Spring 2.0). The
     * post-processor can decide whether to apply to either the FactoryBean or created
     * objects or both through corresponding <code>bean instanceof FactoryBean</code> checks.
     * <p>This callback will also be invoked after a short-circuiting triggered by a
     * {@link InstantiationAwareBeanPostProcessor#postProcessBeforeInstantiation} method,
     * in contrast to all other BeanPostProcessor callbacks.
     * @param bean the new bean instance
     * @param beanName the name of the bean
     * @return the bean instance to use, either the original or a wrapped one; if
     * <code>null</code>, no subsequent BeanPostProcessors will be invoked
     * @throws org.springframework.beans.BeansException in case of errors
     * @see org.springframework.beans.factory.InitializingBean#afterPropertiesSet
     * @see org.springframework.beans.factory.FactoryBean
     */
    Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException;

}

/**已经完成了property 填充（完成InitializingBean 接口的afterPropertiesSet（）调用，如果指定init-method 方法，也已经完成的调用（after..()之后））
　　　

     * Initialize the given bean instance, applying factory callbacks
     * as well as init methods and bean post processors.
     * <p>Called from {@link #createBean} for traditionally defined beans,
     * and from {@link #initializeBean} for existing bean instances.
     * @param beanName the bean name in the factory (for debugging purposes)
     * @param bean the new bean instance we may need to initialize
     * @param mbd the bean definition that the bean was created with
     * (can also be <code>null</code>, if given an existing bean instance)
     * @return the initialized bean instance (potentially wrapped)
     * @see BeanNameAware
     * @see BeanClassLoaderAware
     * @see BeanFactoryAware
     * @see #applyBeanPostProcessorsBeforeInitialization
     * @see #invokeInitMethods
     * @see #applyBeanPostProcessorsAfterInitialization
     */
    protected Object initializeBean(final String beanName, final Object bean, RootBeanDefinition mbd) {
        if (System.getSecurityManager() != null) {
            AccessController.doPrivileged(new PrivilegedAction<Object>() {
                public Object run() {
                    invokeAwareMethods(beanName, bean);
                    return null;
                }
            }, getAccessControlContext());
        }
        else {
            invokeAwareMethods(beanName, bean);
        }

        Object wrappedBean = bean;
        if (mbd == null || !mbd.isSynthetic()) {
            wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);//调用BeanPostProcessor的before方法
        }

        try {
            invokeInitMethods(beanName, wrappedBean, mbd);
        }
        catch (Throwable ex) {
            throw new BeanCreationException(
                    (mbd != null ? mbd.getResourceDescription() : null),
                    beanName, "Invocation of init method failed", ex);
        }

        if (mbd == null || !mbd.isSynthetic()) {
            wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);//调用

BeanPostProcessor的after方法

} return wrappedBean; }

BeanFactory bf =   new XmlBeanFactory(new ClassPathResource("spring.xml"));

bf 只是保存一些BeanDeinationMap， 并不会马上实例化，需要后续调用getBean才初始化：

ApplicationContext ac2 = new ClassPathXmlApplicationContext("spring.xml");

ac2 会马上将spring.xml中定义的bean实例化加到factory的缓存中。

例子用ApplicationContext ：

spring.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:aop="http://www.springframework.org/schema/aop"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:mvc="http://www.springframework.org/schema/mvc"

    xsi:schemaLocation="http://www.springframework.org/schema/beans
      http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
      http://www.springframework.org/schema/context
      http://www.springframework.org/schema/context/spring-context-3.2.xsd
      http://www.springframework.org/schema/aop
      http://www.springframework.org/schema/aop/spring-aop-3.2.xsd
      http://www.springframework.org/schema/tx
      http://www.springframework.org/schema/tx/spring-tx-3.2.xsd
      http://www.springframework.org/schema/mvc
      http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd
      ">
      <alias name="user" alias="testxx"/>
      <bean id="father" abstract="true">
      <property name="local" value="Us"/>
      </bean>
      <bean id="user" class="com.donghua.bean.User" parent="father">
      <property name="name" value="Allen"/>
      <property name="age" value="6"/>
      </bean>
       <bean id="user3" class="com.donghua.bean.User3" init-method="myInit" destroy-method="destroy">
      <property name="name" value="Allen3"/>
      <property name="age" value="61"/>
      </bean>
      <bean id="factory" class="com.donghua.bean.MyBeanFactory"/>
</beans>

　User3:

package com.donghua.bean;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.beans.factory.config.DestructionAwareBeanPostProcessor;

public class User3 implements BeanPostProcessor, InitializingBean, DestructionAwareBeanPostProcessor,BeanFactoryAware
{
	BeanFactory beanFactory;
	private String name;
	private int age;

	public String getName()
	{
		return name;
	}

	public void setName(String name)
	{
		this.name = name;
	}

	public int getAge()
	{
		return age;
	}

	public void setAge(int age)
	{
		this.age = age;
	}

	public void myInit()
	{
		System.out.println("this is my init....."+this.getAge());
	}

	@Override
	public String toString() {
		return "User [name=" + name + ", age=" + age + "]";
	}

	@Override
	public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
		// TODO Auto-generated method stub
		System.out.println("This is the post before..............");
		return bean;
	}

	@Override
	public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
		// TODO Auto-generated method stub
		System.out.println("This is the post after..............");
		return bean;
	}

	@Override
	public void afterPropertiesSet() throws Exception {
		// TODO Auto-generated method stub
		System.out.println("this is InitializingBean method..."
				+ "(called by before init method, after set property values)."+this.getAge());
	}

	@Override
	public void postProcessBeforeDestruction(Object bean, String beanName) throws BeansException {
		// TODO Auto-generated method stub
		System.out.println("this is DestructionAwareBeanPostProcessor, called when destroy bean...");
	}

	public void destroy()
	{
		System.out.println("this is destroy method....");
	}

	@Override
	public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
		// TODO Auto-generated method stub
		this.beanFactory = beanFactory;
	}

	public void getUser2()
	{
		User u =(User) beanFactory.getBean("user");
		System.out.println(u.toString()+" this is user2...");
	}
}

　

package com.donghua.test;

import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.core.io.ClassPathResource;

import com.donghua.anotation.User2;
import com.donghua.bean.MyBeanFactory;
import com.donghua.bean.User;
import com.donghua.bean.User3;

public class Test {

	public static void main(String[] args)
	{
		ApplicationContext ac2 = new ClassPathXmlApplicationContext("spring.xml");
		User3 u3 = (User3) ac2.getBean("user3");
		System.out.println(u3);
		u3.getUser2();
		((ClassPathXmlApplicationContext) ac2).close();  

	}

}

　输出顺序：

this is InitializingBean method...(called by before init method, after set property values).61      //InitializingBean
this is my init.....61　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　//init-method　　　
This is the post before..............　　　　　　　　　　　　　　　　　　　　　　　　　　　　//BeanPostProcesser
This is the post after..............
This is the post before..............
This is the post after..............
User [name=Allen3, age=61]
User [name=Allen, age=6] this is user2...                                                                                  
this is DestructionAwareBeanPostProcessor, called when destroy bean...                                   // DestructionAwareBeanPostProcessor                
this is DestructionAwareBeanPostProcessor, called when destroy bean...
this is destroy method....　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　//destory method