JDK proxy 和cglib 源码解读

1 JDK Proxy 案例

JDK 代理类必须要实现一个接口。
创建接口

package com.gientech.proxy.jdk;

public interface ICalculator {
    public Integer add(Integer i,Integer j);
    public Integer sub(Integer i,Integer j);
    public Integer mul(Integer i,Integer j);
    public Integer div(Integer i,Integer j);
}

创建实现类

package com.gientech.proxy.jdk;

public class MyCalculator implements ICalculator{
    @Override
    public Integer add(Integer i, Integer j) {
        return i+j;
    }

    @Override
    public Integer sub(Integer i, Integer j) {
        return i-j;
    }

    @Override
    public Integer mul(Integer i, Integer j) {
        return i*j;
    }

    @Override
    public Integer div(Integer i, Integer j) {
        return i/j;
    }
}

创建proxy

package com.gientech.proxy.jdk;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;

public class CalculatorProxy {
    public static ICalculator getProxy(final ICalculator calculator){
        ClassLoader loader = calculator.getClass().getClassLoader();
        Class<?>[] interfaces = calculator.getClass().getInterfaces();
        InvocationHandler handler = new InvocationHandler() {
            @Override
            public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                Object result = null;
                try {
                    result = method.invoke(calculator, args);
                }catch (Exception e){
                    System.out.println(e);
                }finally {

                }
                return result;

            }
        };
        Object proxy = Proxy.newProxyInstance(loader, interfaces, handler);
        return (ICalculator) proxy;

    }
}

创建测试类

package com.gientech.proxy.jdk;


public class JDKProxyTest {
    public static void main(String[] args) {
        System.getProperties().put("sun.misc.", "true");
        ICalculator proxy = CalculatorProxy.getProxy(new MyCalculator());
        Integer result = proxy.add(1,1);
        System.out.println("result  ----  " + result);
        System.out.println(proxy.getClass());
    }
}

运行结果如下：

2 Cglib proxy 案例

Classload
创建被代理类

package com.gientech.proxy.cglib;


public class MyCalculator {
    public Integer add(Integer i, Integer j) {
        return i+j;
    }

    public Integer sub(Integer i, Integer j) {
        return i-j;
    }

    public Integer mul(Integer i, Integer j) {
        return i*j;
    }

    public Integer div(Integer i, Integer j) {
        return i/j;
    }
}

创建回调对象

package com.gientech.proxy.cglib;


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

import java.lang.reflect.Method;

public class MyCglib implements MethodInterceptor {


    @Override
    public Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable {
        Object o1 = methodProxy.invokeSuper(o, objects);
        return o1;
    }
}

创建测试类

package com.gientech.proxy.cglib;

import org.springframework.cglib.core.DebuggingClassWriter;
import org.springframework.cglib.proxy.Enhancer;

public class MyCglibTest {

    public static void main(String[] args) {
        // 动态代理创建的class文件村存储到本地
        System.setProperty(DebuggingClassWriter.DEBUG_LOCATION_PROPERTY, "d:\\test\\code");

        // 通过cglib动态代理获取代理对象的过程，创建调用的对象
        Enhancer enhancer = new Enhancer();
        // 设置enhancer对象的父类
        enhancer.setSuperclass(MyCalculator.class);
        // 设置enhancer的回调对象
        enhancer.setCallback(new MyCglib());
        // 创建代理对象
        MyCalculator myCalculator = (MyCalculator) enhancer.create();
        // 通过代理对象调用目标方法
        int result = myCalculator.add(1,2);
        System.out.println(myCalculator.getClass() + "   ---   " + result);
    }
}