[Java知识库]CGLIB动态代理

被代理对象(目标对象)MyService：

package com.example.service;

public class MyService {

    public String doFirst()
    {
        System.out.println("doFirst");
        return "firstResult";
    }

    public String doLast()
    {
        System.out.println("doLast");
        return "lastResult";
    }
}

创建类MyMethodInterceptor实现cglib下的MethodInterceptor接口：

package com.example.proxy;

import net.sf.cglib.proxy.MethodInterceptor;
import net.sf.cglib.proxy.MethodProxy;

import java.lang.reflect.Method;

public class MyMethodInterceptor implements MethodInterceptor {
    private Object target;

    public MyMethodInterceptor() {
        super();
    }

    public MyMethodInterceptor(Object target) {
        super();
        this.target = target;
    }

    @Override
    public Object intercept(Object o, Method method, Object[] args, MethodProxy methodProxy) throws Throwable {

        Object result = null;
        result = method.invoke(target, args);
        System.out.println("添加增强效果");
        if(result instanceof String){
            result += "增强了";
        }

        return result;
    }
}

定义工具类创建代理对象：

package com.example.proxy;

import com.example.service.MyService;
import net.sf.cglib.proxy.Enhancer;

public class FactoryProxy {
    public Object createProxy(Object target)
    {
        //使用cglib创建代理对象

        //1.创建cglib中的关键对象Enhancer
        Enhancer en = new Enhancer();

        //2.指定目标类
        en.setSuperclass(target.getClass());

        //3.指定增强功能的对象
        en.setCallback(new MyMethodInterceptor(target));

        //4.创建代理对象
        return en.create();
    }
}

测试代码：

package com.example.test;

import com.example.proxy.FactoryProxy;
import com.example.service.MyService;

public class CglibTest {
    public static void main(String[] args) {
        //1.创建目标对象
        MyService target = new MyService();

        //2.创建工具类
        FactoryProxy factory = new FactoryProxy();

        //3.调用工具方法，得到代理对象
        MyService proxy = (MyService)factory.createProxy(target);

        //4.通过代理对象，执行业务方法
        String result = proxy.doFirst();
        System.out.println(result);

    }
}

效果：

doFirst
添加增强效果
firstResult增强了