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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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