bean的生命周期

一、流程图

二、各环节介绍

spring管理bean，通过反射找到构造方法，实例化bean对象
Bean实例化后对将Bean的引入和值注入到Bean的属性中
BeanNameAware.setBeanName()，获取设置bean的名称
BeanFactoryAware.setBeanFactory()，获取BeanFactory容器实例即获取bean
ApplicationContextAware.setApplicationContext()，获取bean所在应用上下文引用
BeanPostProcessor.postProcessBeforeInitialization()，前置处理器，获取bean，为bean填充属性
InitializingBean.afterPropertiesSet()，初始化方法
bean使用init-method声明了初始化方法
BeanPostProcessor.postProcessBeforeInitialization()，后置处理器，获取bean
DisposableBean.destory()，销毁方法
bean使用destory-method声明了销毁方法

三、代码测试

public class Book implements BeanNameAware, BeanFactoryAware, ApplicationContextAware,
        InitializingBean, DisposableBean {
    private String bookName;
    public void setBookName(String bookName) {
        System.out.println("book注入属性值");
        this.bookName = bookName;
    }
    public Book() {
        System.out.println("book对象实例化");
    }
    @Override
    public void setBeanName(String name) {
        System.out.println("获取bean名字");
    }
    @Override
    public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
        System.out.println("获取bean工厂实例");
    }
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        System.out.println("获取应用上下文");
    }
    @Override
    public void afterPropertiesSet() throws Exception {
        System.out.println("初始化方法");
    }
    public void definedInit(){
        System.out.println("自定义初始化方法");
    }
    @Override
    public void destroy() throws Exception {
        System.out.println("销毁方法");
    }
    public void definedDestroy(){
        System.out.println("自定义销毁方法");
    }
}

public class MyBeanPostProcessor implements BeanPostProcessor {
    // 容器加载的时候会加载一些其他的bean，会调用初始化前和初始化后方法
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        if(bean instanceof Book){
            System.out.println("BeanPostProcessor.before invoke");
        }
        return bean;
    }
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        if(bean instanceof Book){
            System.out.println("BeanPostProcessor.after invoke");
        }
        return bean;
    }
}

<?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="book" class="com.xc.com.xc.entity.Book" init-method="definedInit" destroy-method="definedDestroy" >
        <property name="bookName" value="西游记"/>
    </bean>
    <bean id="myBeanPostProcessor" class="com.xc.com.xc.entity.MyBeanPostProcessor" />
</beans>

public class Client {
    public static void main(String[] args) {
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("bean.xml");
        Book book = (Book) context.getBean("book");
        context.destroy();
    }
}

结果：
book对象实例化
book注入属性值
获取bean名字
获取bean工厂实例
获取应用上下文
BeanPostProcessor.before invoke
初始化方法
自定义初始化方法
BeanPostProcessor.after invoke
销毁方法
自定义销毁方法