java动态代理 · luowen&weiwei-(luowen ❤️ wwei)

代理模式, 可以只提供方法, 实际操作交给被代理对象去完成, 好处是可以在不修改原来代码基础上新增功能, 也可以优化, 当然还有等等…
简单说下java的三中代理实现

静态代理

JDK8的新特性, 接口中可以有方法体, 主要实现一个print方法

package main.staticproxy;
 public interface JDK8Tools {

     public default void print(Object msg) {
         System.out.println(msg);
     }
 }

学习接口, 定义了三个方法

package main.staticproxy;
public interface Study {

    public abstract void studyJava();

    public abstract void studyPhp();

    public abstract void studyJavaScript();

}

“我”实现了学习接口

package main.staticproxy;
public class StudentOfLuowen implements JDK8Tools, Study {
    @Override
    public void studyJava() {
        print("I love Java");
    }

    @Override
    public void studyPhp() {
        print("I'am paper");
    }

    @Override
    public void studyJavaScript() {
        print("JavaScript is very Hot!!!");
    }
}

通过代理类, 代理我学习, 外面看是”代理类”在学习, 其实是”我”在学习

package main.staticproxy;
public class StudentProxy implements JDK8Tools, Study{
    private StudentOfLuowen studentOfLuowen = null;

    public StudentProxy(StudentOfLuowen studentOfLuowen) {
        this.studentOfLuowen = studentOfLuowen;
    }

    @Override
    public void studyJava() {
        print("proxy luowen Study JavaStart");
        studentOfLuowen.studyJava();
        print("proxy luowen Study JavaEnd");

    }

    @Override
    public void studyPhp() {
        print("proxy luowen Study PHP start");
        studentOfLuowen.studyPhp();
        print("proxy luowen Study PHP end");
    }

    @Override
    public void studyJavaScript() {
        print("proxy luowen Study JavaScript start");
        studentOfLuowen.studyJavaScript();
        print("proxy luowen Study JavaScript end");
    }
}

测试类

package main.staticproxy;
 public class StudentProxyTest {
     public static void main(String[] args) {
         StudentProxy studentProxy = new StudentProxy(new StudentOfLuowen());

         studentProxy.studyJavaScript();
         studentProxy.studyJava();
         studentProxy.studyPhp();
     }
 }

JDK5 反射包中的Proxy代理对象(被代理对象一定要有接口实现, 这是硬伤)

同上JDK8Tools接口和Study接口
同上”我(StudentOfLuowen)”对象实现了 JDK8Tools, Study接口

JDK5 Proxy实现

package main.jdkproxy;

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

public class Jdk5Proxy<T> implements InvocationHandler{

    private T target = null;

    public T bind (T target) {
        this.target = target;
        return (T) Proxy.newProxyInstance(target.getClass().getClassLoader(), target.getClass().getInterfaces(), this);
    }


    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        System.out.println(method.getName() + ": invoke start!!");
        Object result = method.invoke(target, args);
        System.out.println(method.getName() + ": invoke end!!");
        return result;
    }

}

JDK5 Proxy 测试

package main.jdkproxy;

import main.StudentOfLuowen;
import main.Study;

public class Jdk5ProxyTest {
    public static void main(String[] args) {
        Study proxy = new Jdk5Proxy<Study>().bind(new StudentOfLuowen());

        proxy.studyJava();
        proxy.studyJavaScript();
        proxy.studyPhp();
    }
}

cglib动态代理 (完美解决JDK5Proxy代理的问题)

独立的学生, 没有实现任何接口

package main.cglibproxy;
public class IndependentStudent {
    public void studyMath() {
        System.out.println("学习数学");
    }

    public void studyEnglish() {
        System.out.println("学习英语");
    }
}

CGlib代理实现

package main.cglibproxy;

import net.sf.cglib.proxy.Enhancer;
import net.sf.cglib.proxy.MethodInterceptor;
import net.sf.cglib.proxy.MethodProxy;
import java.lang.reflect.Method;
public class CGlibProxy<T> implements MethodInterceptor{

    private T target = null;

    public T bind(T target) {
        this.target = target;
        return (T) Enhancer.create(target.getClass(), this);

        // another implement method
        // Enhancer enhancer = new Enhancer();//该类用于生成代理对象
        // enhancer.setSuperclass(this.target.getClass());//设置父类
        // enhancer.setCallback(this);//设置回调用对象为本身
        // return enhancer.create();
    }

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

测试代码

package main.cglibproxy;

public class CGlibProxyTest {

    public static void main(String[] args) {
        IndependentStudent independentStudent = new CGlibProxy<IndependentStudent>().bind(new IndependentStudent());
        independentStudent.studyEnglish();
        independentStudent.studyMath();
    }
}

PS: 欢迎拍砖