一、概述

spring中有许多扩展点，开发人员可在此基础上扩展和增强，BeanPostProcessor、和BeanFactoryPostProcessor是两个比较重大的扩展点，可以对Bean进行增强(apo)、修改Bean的定义信息、或添加新的Bean定义，下面通过一个小的案例，观察下各自运行的时机。

二、案例实战

1、MyTestStudent类(实现InitializingBean接口)：

public class MyTestStudent implements InitializingBean {

    /**
     * 学生编码
     */
    private Integer stuCode;

    /**
     * 学生名称
     */
    private String stuName;

    public MyTestStudent() {
        System.out.println("---MyTestStudent构造方法被调用");
    }

    public Integer getStuCode() {
        System.out.println("---MyTestStudent#getStuCode方法被调用");
        return stuCode;
    }

    public void setStuCode(Integer stuCode) {
        System.out.println("---MyTestStudent#setStuCode方法被调用");
        this.stuCode = stuCode;
    }

    public String getStuName() {
        System.out.println("---MyTestStudent#getStuName方法被调用");
        return stuName;
    }

    public void setStuName(String stuName) {
        System.out.println("---MyTestStudent#setStuName方法被调用");
        this.stuName = stuName;
    }

    @Override
    public void afterPropertiesSet() {
        System.out.println("---MyTestStudent#afterPropertiesSet方法被调用");
    }
}

2、MyTestBeanPostProcessor类(实现BeanPostProcessor接口)：

public class MyTestBeanPostProcessor implements BeanPostProcessor {

    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        System.out.println("---MyTestBeanPostProcessor#postProcessBeforeInitialization方法被执行，当前对象：" + beanName);
        return bean;
    }

    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        System.out.println("---MyTestBeanPostProcessor#postProcessAfterInitialization方法被执行，当前对象：" + beanName);
        return bean;
    }
}

3、
MyTestBeanFactoryPostProcessor类(实现BeanFactoryPostProcessor接口)：

public class MyTestBeanFactoryPostProcessor implements BeanFactoryPostProcessor {

    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
        System.out.println("---MyTestBeanFactoryPostProcessor#postProcessBeanFactory法被执行");
    }
}

4、myLifeCycle.xml配置文件：

<?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:context="http://www.springframework.org/schema/context"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
                http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd"
       default-autowire="byName">

    <bean id="myTestStudent" class="com.druid.demo.springcycle.MyTestStudent">
        <property name="stuCode" value="101"/>
        <property name="stuName" value="张三"/>
    </bean>
    <bean id="myTestBeanPostProcessor" class="com.druid.demo.springcycle.MyTestBeanPostProcessor"/>
    <bean id="myTestBeanFactoryPostProcessor" class="com.druid.demo.springcycle.MyTestBeanFactoryPostProcessor"/>
</beans>

5、MyMainTest测试类：

public class MyMainTest {
    public static void main(String[] args) {
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("myLifeCycle.xml");
    }
}

6、运行结果输出：

BeanPostProcessor和BeanFactoryPostProcessor区别

1、解析xml配置文件，加载bean定义信息(BeanDefinition)
2、调用BeanFactoryPostProcessor#postProcessBeanFactory方法，可动态新增bean定义信息(BeanDefinition)，
或者修改bean定义信息
3、调用MyTestStudent构造方法
4、为MyTestStudent类设置属性信息(调用两个set方法)
5、调用BeanPostProcessor#postProcessBeforeInitialization方法，进行bean初始化前增强
6、调用MyTestStudent#afterPropertiesSet方法，执行初始化逻辑
7、调用BeanPostProcessor#postProcessAfterInitialization方法，进行bean初始化后增强(aop一般在此实现)