02_动态代理的实现

张创琦

代码部分见 Spring02

二者区别：

JDK需要提供interface 接口，而cglib不需要接口即可完成相关功能。

基础代码

AOP.java

package com.kkb.aop;
/**
 * 切面，服务代码，切入到核心代码当中，给了四个位置，
 */
public interface AOP {
    void before();
    void exception();
    void after();
    void myFinally();
}

LogAOP.java

package com.kkb.aop;
public class LogAOP implements AOP{
    @Override
    public void before() {
        System.out.println("日志------before------");
    }
    @Override
    public void exception() {
        System.out.println("日志------exception------");
    }
    @Override
    public void after() {
        System.out.println("日志------after------");
    }
    @Override
    public void myFinally() {
        System.out.println("日志------finally------");
    }
}

TranAOP.java

package com.kkb.aop;
public class TranAOP implements AOP {
    @Override
    public void before() {
        System.out.println("事务-----before-----");
    }
    @Override
    public void exception() {
        System.out.println("事务-----exception-----");
    }
    @Override
    public void after() {
        System.out.println("事务-----after-----");
    }
    @Override
    public void myFinally() {
        System.out.println("事务-----finally-----");
    }
}

IService.java

package com.kkb.service;
/**
 * 接口定义核心方法
 *
 */
public interface IService {
    void add();
}

TeamService.java

package com.kkb.service;
public class TeamService implements IService{
    @Override
    public void add(){
        System.out.println("TeamService--------add-------");
    }
}

NBAService.java

package com.kkb.cglibProxy;
public class NBAService {
    public int add(String name, int id) {
        System.out.println("NBAService----add---");
        return id;
    }
}

方法1: 基于JDK的动态代理

思想：逐步封装代码，提高代码的简洁性

1.1 基础代码

主要函数就是 teamService

测试：

public static void main(String[] args) {
    //目标对象--被代理对象
    TeamService teamService = new TeamService();
    //返回代理对象  基于JDK的动态代理
    IService proxyService = (IService) Proxy.newProxyInstance(
        teamService.getClass().getClassLoader(),
        teamService.getClass().getInterfaces(),
        new InvocationHandler() {  //回调函数，编写代理规则
            @Override
            public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                try{
                    System.out.println("开始事务");
                    Object invoke = method.invoke(teamService, args);
                    System.out.println("提交事务");
                    return invoke;
                } catch(Exception e) {
                    System.out.println("回滚事务");
                    e.printStackTrace();
                    throw e;
                } finally{
                    System.out.println("finally---------");
                }
            }
        }
    );
    //代理对象干活
        proxyService.add();
        System.out.println(teamService.getClass());  //静态代理，地址为我们自己构建的TeamService
        System.out.println(proxyService.getClass());  //动态代理
    }

1.2 将 InvocationHandler 封装

ProxyHandler.java

public class ProxyHandler implements InvocationHandler {
    private IService service;
    private AOP aop;
    public ProxyHandler(IService service, AOP aop) {
        this.service = service;
        this.aop = aop;
    }
    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        try{
            aop.before();
            Object invoke = method.invoke(service, args);
            aop.after();
            return invoke;
        } catch(Exception e) {
            aop.exception();
            e.printStackTrace();
            throw e;
        } finally{
            aop.myFinally();
        }
    }
}

测试：

public static void main(String[] args) {
    //目标对象--被代理对象
    TeamService teamService = new TeamService();
    //切面
    AOP tranAOP = new TranAOP();
    //返回代理对象  基于JDK的动态代理
    IService proxyService = (IService) Proxy.newProxyInstance(
        teamService.getClass().getClassLoader(),
        teamService.getClass().getInterfaces(),
        new ProxyHandler(teamService, tranAOP)
    );
    //代理对象干活
    proxyService.add();
    System.out.println(teamService.getClass());
    System.out.println(proxyService.getClass());
}

1.3 JDK动态类全部封装

ProxyFactory.java

package com.kkb.dynamicProxy;
import com.kkb.aop.AOP;
import com.kkb.service.IService;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
public class ProxyFactory {
    private IService service; //目标对象
    private AOP aop; //切面
    public ProxyFactory(IService service, AOP aop) {
        this.service = service;
        this.aop = aop;
    }
    /**
     * 获取动态代理的实例
     * @return
     */
    public Object getProxyInstance() {
        return Proxy.newProxyInstance(
            service.getClass().getClassLoader(),
            service.getClass().getInterfaces(),
            new InvocationHandler() {  //回调函数，编写代理规则
                @Override
                public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                    try{
                        aop.before();
                        Object invoke = method.invoke(service, args);
                        aop.after();
                        return invoke;
                    } catch(Exception e) {
                        aop.exception();
                        e.printStackTrace();
                        throw e;
                    } finally{
                        aop.myFinally();
                    }
                }
            }
        );
    }
}

测试：

public static void main(String[] args) {
    IService teamService = new TeamService();
    AOP tranAOP = new TranAOP();
    AOP logAOP = new LogAOP();
    IService service = (IService) new ProxyFactory(teamService, tranAOP).getProxyInstance();
    IService service1 = (IService) new ProxyFactory(service, logAOP).getProxyInstance();
    service1.add(); //核心业务+服务代码 混合在一起的完整代码
}

方法2: 基于cglib的动态代理

2.1 基础代码

public static void main1(String[] args) {
        //目标对象：没有接口
        NBAService nbaService = new NBAService();
        //cglib代理
        NBAService proxyService = (NBAService) Enhancer.create(nbaService.getClass(),
                new MethodInterceptor(){ // 回调函数负责编写代理规则
            @Override
            public Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable {
                try{
                    System.out.println("事务开始");
                    Object invoke = methodProxy.invokeSuper(o, objects);  //最关注的核心的部分
                    System.out.println("事务提交");
                    return invoke;
                } catch(Exception e) {
                    System.out.println("事务回滚");
                    throw e;
                } finally{
                    System.out.println("finally----------");
                }
            }
        });
        //代理对象干活
        int res = proxyService.add("huren", 1001);
        System.out.println(res);
    }

2.2 将回调函数封装

CglibProxyFactory.java

此处事务没有实现接口，而是直接声明了它的Service .

package com.kkb.cglibProxy;
import com.kkb.aop.AOP;
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 CglibProxyFactory {
    //目标对象，没有实现接口
    private NBAService nbaService;
    //切面
    private AOP aop;
    public Object getProxyInstance(NBAService nbaService, AOP aop){
        return Enhancer.create(nbaService.getClass(), new MethodInterceptor() {
            @Override
            public Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable {
                try{
                    aop.before();
                    Object o1 = methodProxy.invokeSuper(o, objects);
                    aop.after();
                    return o1;
                } catch(Exception e) {
                    aop.exception();
                    throw e;
                } finally{
                    aop.myFinally();
                }
            }
        });
    }
}

测试：

public static void main2(String[] args) {
    NBAService nbaService = new NBAService();
    AOP tranAop = new TranAOP();
    NBAService proxyInstance = (NBAService) new CglibProxyFactory().getProxyInstance(nbaService, tranAop);
    int res = proxyInstance.add("huren", 1001);
    System.out.println(res);
}

Java 框架相关文档

02_JDK和cglib实现动态代理

02_动态代理的实现

二者区别：

方法1: 基于JDK的动态代理

1.1 基础代码

1.2 将 InvocationHandler 封装

1.3 JDK动态类全部封装

方法2: 基于cglib的动态代理

2.1 基础代码

2.2 将回调函数封装