（009）spring之BeanFactoryPostProcessor的执行时机和作用

　　BeanFactoryPostProcessor接口中只有一个方法postProcessBeanFactory，该方法在spring容器初始化后执行，并且只执行一次。它会在BeanPostProcessor中的方法执行之前先执行。示例如下：

　　pom.xml

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.edu.spring</groupId>
    <artifactId>spring</artifactId>
    <version>1.0.0</version>

    <name>spring</name>
    <!-- FIXME change it to the project's website -->
    <url>http://www.example.com</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>
    
    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>4.3.2.RELEASE</version>
        </dependency>
    </dependencies>

</project>

　　User.java

package com.edu.spring;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;

public class User {

private ApplicationContext applicationContext;
    
    public void init(){
        System.out.println("User init()");
    }
    public void show(){
        System.out.println("User show(): "+applicationContext);
    }
    
    @Autowired
    public void setApplicationContext(ApplicationContext applicationContext) {
        System.out.println("------set()-----");
        this.applicationContext = applicationContext;
    }
    
}

　　MyConfig.java

package com.edu.spring;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class MyConfig {

    @Bean(initMethod="init")
    public User createUser(){
        return new User();
    }
}

　　EchoBeanPostProcssor.java

package com.edu.spring;

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

 
@Component
public class EchoBeanPostProcssor implements BeanPostProcessor {

    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName)
            throws BeansException {
        // TODO Auto-generated method stub
        System.out.println("-------------postProcessBeforeInitialization-------------"+bean.getClass());
        return bean;
    }


    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName)
            throws BeansException {
        // TODO Auto-generated method stub
        System.out.println("-------------postProcessAfterInitialization-------------"+bean.getClass());
        return bean;
    }

}

　　MyBeanFactoryPostProcessor.java

package com.edu.spring;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.stereotype.Component;

@Component
public class MyBeanFactoryPostProcessor implements BeanFactoryPostProcessor {

    @Override
    public void postProcessBeanFactory(
            ConfigurableListableBeanFactory beanFactory) throws BeansException {
        // TODO Auto-generated method stub
        System.out.println("--------------------"+beanFactory.getBeanDefinitionCount());
    }

}

　　运行结果如下：