spring中bean的生命周期详解

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本文详细介绍了Spring框架中Bean的生命周期，包括从Bean的创建到销毁过程中经历的各种回调方法及事件。文章通过具体代码示例展示了如何实现Bean初始化和销毁的方法，并使用BeanPostProcessor进行后置处理。

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spring中bean的生命周期详解

首先，beans.xml文件配置

<?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:tx="http://www.springframework.org/schema/tx"
        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
                http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd
                http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd">
<bean id="personService" class="com.beanlife.PersonService" init-method="init"  destroy-method="destoryBean">
        <property name="name" >
                <value>siege</value>
        </property>
</bean>
<bean id="myBeanPostProcessor"  class="com.beanlife.MyBeanPostProcessor">
</bean>
</beans>

PersonService.java
package com.beanlife;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.BeanNameAware;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;

public class PersonService implements BeanNameAware,BeanFactoryAware,ApplicationContextAware,InitializingBean,DisposableBean{
    public PersonService() {
        super();
        System.out.println("PersonService被创建");
    }

    private String name;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
        System.out.println("setName被调用");
    }

    public void showName(){
        System.out.println(this.name);
    }

    @Override
    public void setApplicationContext(ApplicationContext appliactionContext)throws BeansException {
        System.out.println(appliactionContext);
    }

    @Override
    public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
        System.out.println(beanFactory);
    }

    @Override
    public void setBeanName(String  beanName) {
        System.out.println(beanName);
    }

    @Override
    public void afterPropertiesSet() throws Exception {
        System.out.println("调用afterPropertiesSet()方法");
    }

    public void init(){
        System.out.println("init方法被调用");
    }

    public void destoryBean(){
        System.out.println("destoryBean方法被调用");
    }

    @Override
    public void destroy() throws Exception {
        System.out.println("destroy");
    }
}

继承BeanPostProcessor实现后置处理器的MyBeanPostProcessor.java

package com.beanlife;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;


public class MyBeanPostProcessor implements BeanPostProcessor {

    @Override
    public Object postProcessAfterInitialization(Object arg0, String arg1)throws BeansException {
        System.out.println("*********postProcessAfterInitialization**************");
        System.out.println(arg0);
        System.out.println(arg1);
        System.out.println("*********postProcessAfterInitialization**************");
        return arg0;
    }

    @Override
    public Object postProcessBeforeInitialization(Object arg0, String arg1)throws BeansException {
        System.out.println("*********postProcessBeforeInitialization**************");
        System.out.println(arg0);
        System.out.println(arg1);
        System.out.println("*********postProcessBeforeInitialization**************");
        return arg0;
    }

}

测试类Test.java



package com.beanlife;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Test {

    public static void main(String[] args) {
        ApplicationContext ac=new ClassPathXmlApplicationContext("com/beanlife/beans.xml");
        PersonService p=(PersonService) ac.getBean("personService");
        p.showName();
    }

}

测试结果如下:

PersonService被创建  
setName被调用  
personService  
org.springframework.beans.factory.support.DefaultListableBeanFactory@a068d1: defining beans [personService,myBeanPostProcessor]; root of factory hierarchy  
org.springframework.context.support.ClassPathXmlApplicationContext@75222b: display name [org.springframework.context.support.ClassPathXmlApplicationContext@75222b]; startup date [Sat Jan 31 21:36:08 CST 2015]; root of context hierarchy  
*********postProcessBeforeInitialization**************  
com.beanlife.PersonService@4f701  
personService  
*********postProcessBeforeInitialization**************  
调用afterPropertiesSet()方法  
init方法被调用  
*********postProcessAfterInitialization**************  
com.beanlife.PersonService@4f701  
personService  
*********postProcessAfterInitialization**************  
siege

若通过beanFactory获取bean,即修改Test.java文件为:

BeanFactory factory=new XmlBeanFactory(new ClassPathResource("com/beanlife/beans.xml"));
PersonService p=(PersonService) factory.getBean("personService");

则测试结果为:

PersonService被创建  
setName被调用  
personService  
org.springframework.beans.factory.xml.XmlBeanFactory@11274d2: defining beans [personService,myBeanPostProcessor]; root of factory hierarchy  
调用afterPropertiesSet()方法  
init方法被调用  
siege

整个bean的生命周期如下图:

这里写图片描述