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Spring Bean的生命周期
在传统的java应用中，bean的生命周期由new进行bean的实例化，然后该bean就可以使用了，当bean不被使用时，由java自动进行垃圾回收。
然而Spring的生命周期相对比较复杂：
1.Spring对bean进行实例化，即调用构造器
public MyBean01(){ System.out.println("MyBean01 构造"); }
2.Spring将值和bean的引用注入到bean对应的属性中，即调用set~方法
public void setName(String name) { System.out.println("MyBean01 值注入属性中"); this.name = name; }
3.如果该bean实现了BeanNameAware接口，Spring将bean的id传递给setBeanName()方法
@Override public void setBeanName(String name) { System.out.println("MyBean01 id: "+name); }
4.如果该bean实现了BeanFactoryAware接口，Spring将调用setBeanFactory()方法，将BeanFactory实例传入
@Override public void setBeanFactory(BeanFactory beanFactory) throws BeansException { System.out.println("BeanFactory 中有 b1 这个bean： "+beanFactory.containsBean("b1")); System.out.println("BeanFactory 调用MyBean02.class："+beanFactory.getBean(MyBean02.class).toString()); }
5.如果该bean实现了ApplicationContextAware接口，Spring将调用setApplicationContext()方法，将bean所在的应用上下文的引用传入
@Override public void setApplicationContext(ApplicationContext applicationContext) throws BeansException { applicationContext.isSingleton(name); }
6.如果bean实现了BeanPostProcessor接口，Spring将调用它的postProcessBeforeInitialization方法
@Override public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException { //在这里可以修改bean的属性，返回时得返回bean，不然程序不予执行 return bean; }
7.如果bean实现了InitializingBean接口，Spring将调用它的afterPropertiesSet()方法，另一种方法是在xml文件中配置init-method
<bean id="b1" class="com.spring.cycle.MyBean01" init-method="init"
destroy-method="distory"> <property name="name" value=http://www.mamicode.com/"tom"></property></bean>
8.如果bean实现了BeanPostProcessor接口，Spring将调用它的postProcessAfterInitialization，与步骤6协同操作卡住步骤7(init)
@Override public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException { // TODO Auto-generated method stub return null; }
9.此时，bean已经准备就绪，一直存在应用上下文中，直到该应用上下文被销毁
10.当应用上下文关闭时，如果bean实现了DisposableBean接口，Spring将调用它的destory()方法，或者在xml文件中配置destory-method
以下是4段代码，以供测试
package com.spring.cycle;import org.springframework.beans.factory.BeanNameAware;public class MyBean01 implements BeanNameAware{ public MyBean01(){ System.out.println("MyBean01 构造"); } @Override protected void finalize() throws Throwable { System.out.println("MyBean01 finalize"); super.finalize(); } public void init(){ System.out.println("MyBean01 init"); } public void distory(){ System.out.println("MyBean01 distory"); } private String name; public void setName(String name) { System.out.println("MyBean01 值注入属性中"); this.name = name; } @Override public String toString() { return "MyBean01: name--> "+name; } @Override public void setBeanName(String name) { System.out.println("MyBean01 id: "+name); }}
package com.spring.cycle;import org.springframework.beans.BeansException;import org.springframework.beans.factory.BeanFactory;import org.springframework.beans.factory.BeanFactoryAware;import org.springframework.beans.factory.config.BeanPostProcessor;import org.springframework.context.ApplicationContext;import org.springframework.context.ApplicationContextAware;public class MyBean02 implements BeanFactoryAware,ApplicationContextAware,BeanPostProcessor{ public MyBean02(){ System.out.println("MyBean02 构造"); } @Override protected void finalize() throws Throwable { System.out.println("MyBean02 finalize"); super.finalize(); } private void init(){ System.out.println("MyBean02 init"); } private void distory(){ System.out.println("MyBean02 distory"); } private String name; public void setName(String name) { System.out.println("MyBean02 值注入属性中"); this.name = name; } @Override public String toString() { return "MyBean02: name--> "+name; } @Override public void setBeanFactory(BeanFactory beanFactory) throws BeansException { System.out.println("MyBean02 BeanFactory 中有 b1 这个bean： "+beanFactory.containsBean("b1")); System.out.println("MyBean02 BeanFactory 调用MyBean02.class："+beanFactory.getBean(MyBean02.class).toString()); } @Override public void setApplicationContext(ApplicationContext applicationContext) throws BeansException { //applicationContext.isSingleton(name); System.out.println("MyBean02 applicationContext......."); } @Override public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException { //在这里可以修改bean的属性，返回时得返回bean，不然程序不予执行 return bean; } @Override public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException { // TODO Auto-generated method stub return null; }}
<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> <bean id="b1" class="com.spring.cycle.MyBean01" init-method="init" destroy-method="distory"> <property name="name" value=http://www.mamicode.com/"tom"></property> </bean> <bean id="b2" class="com.spring.cycle.MyBean02" init-method="init" destroy-method="distory"> <property name="name" value=http://www.mamicode.com/"jerry"></property> </bean></beans>
package com.spring.cycle;import org.springframework.context.ConfigurableApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;public class TestMain { public static void main(String[] args) { ConfigurableApplicationContext context = new ClassPathXmlApplicationContext("com/spring/cycle/bean-cycle.xml"); MyBean01 b1 = (MyBean01) context.getBean("b1"); MyBean02 b2 = (MyBean02) context.getBean("b2"); System.out.println(b1); System.out.println(b2); context.close(); }}
Spring Bean的生命周期
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