JDK动态代理的实现原理

1、示例demo

计算接口

package com.zcqby.proxy.jdk;

public interface Calculator {

    public int add(int i, int j);

    public int sub(int i, int j);

    public int mult(int i, int j);

    public int div(int i, int j);
}

实现类

package com.zcqby.proxy.jdk;

public class MyCalculator implements Calculator {
    @Override
    public int add(int i, int j) {
        int result = i + j;
        return result;
    }

    @Override
    public int sub(int i, int j) {
        int result = i - j;
        return result;
    }

    @Override
    public int mult(int i, int j) {
        int result = i * j;
        return result;
    }

    @Override
    public int div(int i, int j) {
        int result = i / j;
        return result;
    }
}

代理类

package com.zcqby.proxy.jdk;

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

public class CalculatorProxy {
    public static Calculator getProxy(final Calculator calculator){
        ClassLoader loader = calculator.getClass().getClassLoader();
        Class<?>[] interfaces = calculator.getClass().getInterfaces();
        InvocationHandler h = 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) {
                } finally {
                }
                return result;
            }
        };
        Object proxy = Proxy.newProxyInstance(loader, interfaces, h);
        return (Calculator) proxy;
    }
}

测试类

package com.zcqby.proxy.jdk;

public class Test {
    public static void main(String[] args) {
        System.getProperties().put("sun.misc.ProxyGenerator.saveGeneratedFiles", "true");
        Calculator proxy = CalculatorProxy.getProxy(new MyCalculator());
        proxy.add(1,1);
        proxy.div(10,100);
        System.out.println(proxy.getClass());
    }
}