java 动态代理 proxy gclib

 

代理分两种：静态代理、动态代理

静态代理：创建一个工具，传入实体引用，在通过引用点方法执行

接口名 target；

public 构造方法（接口名 target）{

this.target=target;

}

@Override

public Object execute(){

//操作前

target.execute()

//操作后

}

=======================以上是静态代理====================

动态代理：

通过jdk proxy 或 cglib 等工具生成一个代理的类再加载到jvm中运行

InvocationHandlerTool
MainTest
MethedInvocationHandler
ProxyGeneratorUtils
UserService
UserServiceImp

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

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

/**
 * @author XQQ
 * @create 2018-09-21 11:07
 * @desc
 **/
public class MainTest {


    public static void main(String[] args) {


        UserService userService=new UserServiceImp();
        InvocationHandlerTool proxy=new InvocationHandlerTool(userService);
        UserService o = (UserService) Proxy.newProxyInstance(userService.getClass().getClassLoader(), userService.getClass().getInterfaces(), proxy);
        o.sayHello();

        System.out.println("--proxy---简单粗暴-------");
        UserService o2 =(UserService) Proxy.newProxyInstance(userService.getClass().getClassLoader(), userService.getClass().getInterfaces(), new InvocationHandler() {
            @Override
            public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                method.invoke(userService, args);
                return null;
            }
        });
        o2.sayHello();
        System.out.println("--proxy---简单粗暴-------");


        System.out.println("--proxy---简单实用-------");
        UserService bind =(UserService) proxy.bind(userService);
        bind.sayHello();
        System.out.println("--proxy---简单实用-------");



        System.out.println("--methodInterceptor---常用-------");
        MethodInterceptor methodInterceptor=new MethedInvocationHandler();
        Enhancer enhancer=new Enhancer();
        enhancer.setSuperclass(UserServiceImp.class);
        enhancer.setCallback(methodInterceptor);

        UserService o1 = (UserService)enhancer.create();
        o1.sayHello();

        System.out.println("--methodInterceptor---常用-------");




        System.out.println("--CGLIB---简单粗暴-------");
        enhancer.setSuperclass(UserServiceImp.class);
        enhancer.setCallback(new MethodInterceptor(){

            @Override
            public Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable {
                methodProxy.invokeSuper(o,objects);
                return null;
            }
        });
        UserService service= (UserService) enhancer.create();
        userService.sayHello();
        System.out.println("--CGLIB---简单粗暴-------");


        System.out.println("--proxyGenerator 生成代理类-------");
        ProxyGeneratorUtils.writeProxyClassToHardDisk("$Proxy11.class");
        System.out.println("--CGLIB---简单粗暴-------");
    }


}

执行结果：

进入:sayHello
方法业务代码
进入 end:sayHello
--proxy---简单粗暴-------
方法业务代码
--proxy---简单粗暴-------
--proxy---简单实用-------
进入:sayHello
方法业务代码
进入 end:sayHello
--proxy---简单实用-------
--methodInterceptor---常用-------
sayHello
方法业务代码
sayHello
--methodInterceptor---常用-------
--CGLIB---简单粗暴-------
方法业务代码
--CGLIB---简单粗暴-------
--proxyGenerator 生成代理类-------
--CGLIB---简单粗暴-------

Process finished with exit code 0

public interface UserService {
    void sayHello();
}

public class UserServiceImp implements UserService {
    @Override
    public void sayHello() {

        System.out.println("方法业务代码");
    }
}


public class InvocationHandlerTool implements InvocationHandler {
    private Object target;

    public InvocationHandlerTool(Object target){
        this.target=target;
    }


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

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {

        System.out.println("进入:"+method.getName());

        Object invoke = method.invoke(target, args);

        System.out.println("进入 end:"+method.getName());
        return invoke;
    }
}

public class MethedInvocationHandler implements MethodInterceptor{
    @Override
    public Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable {

        System.out.println(method.getName());
        Object o1 = methodProxy.invokeSuper(o, objects);
        System.out.println(method.getName());
        return o1;

    }
}


public class ProxyGeneratorUtils {
    /**
     * 把代理类的字节码写到硬盘上
     *
     * @param path 保存路径
     */
    public static void writeProxyClassToHardDisk(String path) {
        // 第一种方法，这种方式在刚才分析ProxyGenerator时已经知道了
         System.getProperties().put("sun.misc.ProxyGenerator.saveGeneratedFiles", true);

        // 第二种方法

        // 获取代理类的字节码
        byte[] classFile = ProxyGenerator.generateProxyClass("$Proxy11", UserServiceImp.class.getInterfaces());

        FileOutputStream out = null;

        try {
            out = new FileOutputStream(path);
            out.write(classFile);
            out.flush();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                out.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

 

全部代码都在上面了。proxy 和 cglib两种方式

<!-- https://mvnrepository.com/artifact/cglib/cglib -->
<dependency>
   <groupId>cglib</groupId>
   <artifactId>cglib</artifactId>
   <version>2.2.2</version>
</dependency>