Spring框架学习之第6节

• bean的生命周期

为什么总是一个生命当做一个重点？

Servlet –> servlet生命周期

Java对象生命周期

往往笔试，面试总喜欢问生命周期的问题？

①   实例化（当我们的程序加载beans.xml文件时）把我们的bean（前提是单态的即scope=singleton）实例化到内存

②   调用set方法设置属性

③   如果你实现了bean名字关注接口（BeanNameAware）则，可以通过setBeanName获取id号

④   如果你实现了bean工厂关注接口，则（BeanFactoryAware）则可以获取bean工厂，beanFactory

⑤   如果你实现了ApplicationContextAware接口，则调用方法

public void setApplicationContext(ApplicationContext arg0)

throws BeansException {

// TODO Auto-generated method stub

System.out.println("setApplicationContext"+arg0);

}

⑥   如果bean和一个后置处理器关联了，则会自动去调用Object postProcessBeforeInitialization方法

⑦   了InitializingBean接口，则会调用afterPropertiesSet方法

⑧   如果自己在<bean init-method=”init”>则可以在bean中定义自己的初始化方法

⑨   如果bean和一个后置处理器关联了，则会自动去调用Object postProcessAfterInitialization方法

⑩   使用我们的bean

?   容器关闭

?   可以通过实现DisposableBean接口来调用方法destroy

?   可以在<bean destroy-method=”fun1” /> 调用定制的销毁方法

小结：

我们在实际开发中往往没有用到这么多的过程，常见的过程是

1--2--6-10-9-11

问题：通过BeanFactory来获取bean对象，bean的生命周期是否和Applicationcontext 是一样吗?

不是一样，bean在工厂中创建的生命周期会简单一些

具体

项目结构

beans.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:aop="http://www.springframework.org/schema/aop"
		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/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd
			http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd">

<bean id="personService" destroy-method="mydestroy" init-method="init" class="com.litao.beanlife.PersonService">
<!-- -这里注入我们属性，前提就是有setName才能OK -->
<property name="name">
<value>xiaoming</value>
</property>
</bean>

<bean id="personService2" class="com.litao.beanlife.PersonService">
<!-- -这里注入我们属性，前提就是有setName才能OK -->
<property name="name">
<value>xiaohong</value>
</property>
</bean>

<!-- 配置我们自己的后置处理器（有点类似我们的fiter） -->
<bean id="myBeanPostProcessor" class="com.litao.beanlife.MyBeanPostProcessor" />

</beans>

App1.java

package com.litao.beanlife;

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;

public class App1 {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		ApplicationContext ac = new ClassPathXmlApplicationContext("com/litao/beanlife/beans.xml");
		//BeanFactory factory = new XmlBeanFactory(new ClassPathResource("com/litao/beanlife/beans.xml"));
		PersonService ps = (PersonService)ac.getBean("personService");
		//PersonService ps = (PersonService)factory.getBean("personService");
		ps.sayHi();

	}

}

MyBeanPostProcessor.java

package com.litao.beanlife;

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

public class MyBeanPostProcessor implements BeanPostProcessor {

	//arg0就是beans.xml中要被实例的bean对象
	public Object postProcessAfterInitialization(Object arg0, String arg1)
			throws BeansException {
		// TODO Auto-generated method stub
		System.out.println("postProcessAfterInitialization函数被调用");
		System.out.println(arg0+" 被创建的时间是"+new java.util.Date());
		return arg0;
	}

	@Override
	public Object postProcessBeforeInitialization(Object arg0, String arg1)
			throws BeansException {
		// TODO Auto-generated method stub
		System.out.println("postProcessBeforeInitialization函数被调用");
		return arg0;
	}

}

PersonService.java

package com.litao.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{

	private String name;

	public PersonService(){
		System.out.println("PersonService构造函数被调用");
	}

	public PersonService(String abc){
		System.out.println("PersonService构造函数被调用");
	}

	public String getName() {
		return name;
	}

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

	public void sayHi(){
		System.out.println("hi "+ name);
	}

	//该方法可以给arg0传送正在被实例化的bean的id是什么
	public void setBeanName(String arg0) {
		// TODO Auto-generated method stub
		System.out.println("setBeanName被调用 值为"+arg0);

	}

	//该方法可以传递beanFactory
	public void setBeanFactory(BeanFactory arg0) throws BeansException {
		// TODO Auto-generated method stub
		System.out.println("setBeanFactory "+arg0);
	}

	//该方法传递上下文ApplicationContext
	public void setApplicationContext(ApplicationContext arg0)
			throws BeansException {
		// TODO Auto-generated method stub
		System.out.println("setApplicationContext"+arg0);
	}

	public void init(){
		System.out.println("我自己的init方法");
	}

	@Override
	public void afterPropertiesSet() throws Exception {
		// TODO Auto-generated method stub
		System.out.println("afterPropertiesSet()");
	}

	//定制我们的销毁方法
	public void mydestroy() {
		// TODO Auto-generated method stub
		//我们可以关闭数据连接，socket，文件流，释放该bean的资源
		System.out.println("释放各种资源");

	}	

}