resolveBeforeInstantiation

代理类

try {
   // Give BeanPostProcessors a chance to return a proxy instead of the target bean instance.
   // 给BeanPostProcessors一个机会来返回代理来替代真正的实例，应用实例化前的前置处理器,用户自定义动态代理的方式，针对于当前的被代理类需要经过标准的代理流程来创建对象
   Object bean = resolveBeforeInstantiation(beanName, mbdToUse);
   if (bean != null) {
      return bean;
   }
}

实现InstantiationAwareBeanPostProcessor

public class MyInstantiationAwareBeanPostProcessor implements InstantiationAwareBeanPostProcessor {

    @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 new BeforeInstantiation();
        }
        return null;
    }

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

        return false;
    }

    @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 PropertyValues postProcessProperties(PropertyValues pvs, Object bean, String beanName) throws BeansException {
        System.out.println("beanName:"+beanName+"----执行postProcessProperties方法");

        return pvs;
    }
}

public class BeforeInstantiation {

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

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;
    }
}

<?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="BeforeInstantiation"></bean>
    <bean id="myInstantiationAwareBeanPostProcessor" class="MyInstantiationAwareBeanPostProcessor"></bean>
</beans>

test

public class Test {

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