BeanPostProcessor 结构图

1 code 如下：

package com.gientech.resolveBeforeInstantiation;

public class BeforeInstantiation {

    public void doSomething(){
        System.out.println("do some thing ......");
    }
}

package com.gientech.resolveBeforeInstantiation;


import org.springframework.cglib.proxy.MethodInterceptor;
import org.springframework.cglib.proxy.MethodProxy;

import java.lang.reflect.Method;

public class MyMethodInterceptor implements MethodInterceptor {

    @Override
    public Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable {
        System.out.println("目标方法执行之前： " + method);
        Object o1 = methodProxy.invokeSuper(o, objects);
        System.out.println("目标方法执行之后： " + method);
        return o1;
    }
}

BeanPostProcessor 接口中有postProcessBeforeInitialization，postProcessAfterInitialization 两个方法，
InstantiationAwareBeanPostProcessor 接口中有postProcessBeforeInstantiation，postProcessAfterInstantiation，postProcessProperties 方法
MyInstantiationAwareBeanPostProcessor 继承了InstantiationAwareBeanPostProcessor 接口，所以 在MyInstantiationAwareBeanPostProcessor 中需要实现5个方法。

package com.gientech.resolveBeforeInstantiation;

import org.springframework.beans.BeansException;
import org.springframework.beans.PropertyValues;
import org.springframework.beans.factory.config.InstantiationAwareBeanPostProcessor;
import org.springframework.cglib.proxy.Enhancer;

public class MyInstantiationAwareBeanPostProcessor implements InstantiationAwareBeanPostProcessor {
    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        System.out.println("beanName:"+beanName+"----执行postProcessBeforeInitialization方法");
        return bean;
    }

    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        System.out.println("beanName:"+beanName+"----执行postProcessAfterInitialization方法");
        return bean;
    }

    @Override
    public Object postProcessBeforeInstantiation(Class<?> beanClass, String beanName) throws BeansException {
        System.out.println("beanName:"+beanName+"----执行postProcessBeforeInstantiation方法");
        if (beanClass == BeforeInstantiation.class){
            Enhancer enhancer = new Enhancer();
            enhancer.setSuperclass(beanClass);
            enhancer.setCallback(new MyMethodInterceptor());
            BeforeInstantiation beforeInstantiation = (BeforeInstantiation) enhancer.create();
            System.out.println("创建代理对象： " + beforeInstantiation);
            return beforeInstantiation;
        }
        return beanClass;
    }

    @Override
    public boolean postProcessAfterInstantiation(Object bean, String beanName) throws BeansException {
        return false;
    }


    @Override
    public PropertyValues postProcessProperties(PropertyValues pvs, Object bean, String beanName) throws BeansException {
        return pvs;
    }
}

配置文件如下：

<?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="beforeInstantiation" class="com.gientech.resolveBeforeInstantiation.BeforeInstantiation"></bean>
    <bean id="myInstantiationAwareBeanPostProcessor" class="com.gientech.resolveBeforeInstantiation.MyInstantiationAwareBeanPostProcessor"></bean>
    
</beans>

package com.gientech.resolveBeforeInstantiation;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class BeforeInstantiationTest {

    public static void main(String[] args) {
        ApplicationContext ac = new ClassPathXmlApplicationContext("BeforeInstantiation.xml");
        BeforeInstantiation bean = ac.getBean(BeforeInstantiation.class);
        bean.doSomething();
    }
}

运行结果如下

创建完成后Bean在内存中的名称如下