【Spring源码解析】Bean生命周期

Bean创建过程

1. 实例化bean 设置bean属性
2. Aware(注入Bean ID、BeanFactory和AppCtx)
3. BeanPostProcessor(s).postProcessBeforeInitialization
4. InitializingBean(s).afterPropertiesSet
5. 定制的Bean init方法
6. BeanPostProcessor(s).postProcessAfterInitialization
7. Bean初始化完毕

Bean销毁过程

1. 若实现了DisposableBean接口，则会调用destory方法
2. 若配置了destory-method属性，则会调用其配置的销毁方法

各种接口方法分类

1. Bean自身的方法
   • Bean本身调用的方法
   • 通过配置文件中的init-method和destroy-method指定的方法
2. Bean级生命周期接口方法
   • BeanNameAware
   • BeanFactoryAware
   • InitializingBean
   • DiposableBean
3. 容器级生命周期接口方法
   • BeanPostProcessor
   • InstantiationAwareBeanPostProcessor
4. 工厂后处理器接口方法(容器级，在应用上下文装配配置文件之后立即调用)
   • AspectJWeavingEnabler
   • ConfigurationClassPostProcessor
   • CustomAutowireConfigure

测试Demo

• LifeCycleBean

package com.example.spring.bean;

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

public class LifeCycleBean implements BeanPostProcessor, BeanNameAware,
        BeanClassLoaderAware, BeanFactoryAware, InitializingBean, DisposableBean {

    private String name;

    public LifeCycleBean() {
        System.out.println("-----------------------1.Bean构造器");
    }
    public void setName(String name) {
        System.out.println("-----------------------2.Bean属性注入");
        this.name = name;
    }
    @Override
    public void setBeanName(String name) {
        System.out.println("-----------------------3.BeanNameAware的setBeanName()");
    }

    @Override
    public void setBeanClassLoader(ClassLoader classLoader) {
        System.out.println("-----------------------4.BeanClassLoaderAware的setBeanClassLoader()");
    }

    @Override
    public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
        System.out.println("-----------------------5.BeanFactoryAware的setBeanFactory()");
    }



    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        System.out.println("-----------------------6.[初始化之前]BeanPostProcessor的postProcessBeforeInitialization()");
        return bean;
    }
    @Override
    public void afterPropertiesSet() throws Exception {
        System.out.println("-----------------------7.[初始化中，属性注入后]InitializingBean的afterPropertiesSet()");
    }
    public void initMethod() {
        System.out.println("-----------------------8.调用<bean>的init-method属性自定义的初始化方法");
    }
    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        System.out.println("-----------------------9.[初始化之后]BeanPostProcessor的postProcessAfterInitialization()");
        return bean;
    }

    public void normalMethod() {
        System.out.println("-----------------------10.[容器初始化完成]程序运行，当JVM关闭时，销毁容器");
    }

    @Override
    public void destroy() throws Exception {
        System.out.println("-----------------------11.[容器销毁]DisposableBean的destroy()");
    }

    public void destroyMethod() {
        System.out.println("-----------------------12.[容器销毁]调用<bean>的destory-method属性自定义的销毁方法");
    }

    public String getName() {
        return name;
    }
}

• spring-bean-life-cycle.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"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="lifeCycleBean" class="com.example.spring.bean.LifeCycleBean" destroy-method="destroyMethod" init-method="initMethod">
        <property name="name" value="name"/>
    </bean>

</beans>

• Test

public class SpringTest {
    /**
     * 测试Bean生命周期
     * */
    @Test
    public void testBeanLifeCycle() {
        ClassPathResource resource = new ClassPathResource("spring-bean-life-cycle.xml");
        DefaultListableBeanFactory factory = new DefaultListableBeanFactory();
        factory.addBeanPostProcessor(new LifeCycleBean());
        XmlBeanDefinitionReader reader = new XmlBeanDefinitionReader(factory);
        reader.loadBeanDefinitions(resource);

        LifeCycleBean lifeCycleBean = (LifeCycleBean) factory.getBean("lifeCycleBean");
        lifeCycleBean.normalMethod();

        factory.destroySingleton("lifeCycleBean");
    }
}