java使用动态代理来实现AOP(日志记录)的实例代码

  • Z时代
  • 2024-01-10
  • 分类：IT

下面是一个AOP实现的简单例子：

首先定义一些业务方法：

代码如下:
/** * Created with IntelliJ IDEA. * Author: wangjie  email:tiantian.china.2@gmail.com * Date: 13-9-23 * Time: 下午3:49 */public interface BussinessService {    public String login(String username, String password);    public String find();}

public class BussinessServiceImpl implements BussinessService {    private Logger logger = Logger.getLogger(this.getClass().getSimpleName());

    @Override    public String login(String username, String password) {        return "login success";    }

    @Override    public String find() {        return "find success";    }

}

代码如下:
/** * Created with IntelliJ IDEA. * Author: wangjie  email:tiantian.china.2@gmail.com * Date: 13-9-24 * Time: 上午10:27 */public interface WorkService {    public String work();    public String sleep();}

public class WorkServiceImpl implements WorkService{    @Override    public String work() {        return "work success";    }

    @Override    public String sleep() {        return "sleep success";    }}实现InvocationHandler接口，使用map来存储不同的InvocationHandler对象，避免生成过多。

代码如下:
package com.wangjie.aoptest2.invohandler;

import java.lang.reflect.InvocationHandler;import java.lang.reflect.Method;import java.lang.reflect.Proxy;import java.util.Arrays;import java.util.HashMap;import java.util.logging.Logger;

/** * Created with IntelliJ IDEA. * Author: wangjie  email:tiantian.china.2@gmail.com * Date: 13-9-23 * Time: 下午3:47 */public class LogInvoHandler implements InvocationHandler{    private Logger logger = Logger.getLogger(this.getClass().getSimpleName());

    private Object target; // 代理目标    private Object proxy; // 代理对象

    private static HashMap<Class<?>, LogInvoHandler> invoHandlers = new HashMap<Class<?>, LogInvoHandler>();

    private LogInvoHandler() {    }

    /**     * 通过Class来生成动态代理对象Proxy     * @param clazz     * @return     */    public synchronized static<T> T getProxyInstance(Class<T> clazz){        LogInvoHandler invoHandler = invoHandlers.get(clazz);

        if(null == invoHandler){            invoHandler = new LogInvoHandler();            try {                T tar = clazz.newInstance();                invoHandler.setTarget(tar);                invoHandler.setProxy(Proxy.newProxyInstance(tar.getClass().getClassLoader(),                        tar.getClass().getInterfaces(), invoHandler));            } catch (Exception e) {                e.printStackTrace();            }            invoHandlers.put(clazz, invoHandler);

        }

        return (T)invoHandler.getProxy();    }

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

        Object result = method.invoke(target, args); // 执行业务处理

        // 打印日志        logger.info("____invoke method: " + method.getName()                    + "; args: " + (null == args ? "null" : Arrays.asList(args).toString())                    + "; return: " + result);

        return result;    }

    public Object getTarget() {        return target;    }

    public void setTarget(Object target) {        this.target = target;    }

    public Object getProxy() {        return proxy;    }

    public void setProxy(Object proxy) {        this.proxy = proxy;    }}然后编写一个Test类测试：

代码如下:
/** * Created with IntelliJ IDEA. * Author: wangjie  email:tiantian.china.2@gmail.com * Date: 13-9-24 * Time: 上午9:54 */public class Test {    public static Logger logger = Logger.getLogger(Test.class.getSimpleName());    public static void main(String[] args) {

        BussinessService bs = LogInvoHandler.getProxyInstance(BussinessServiceImpl.class);        bs.login("zhangsan", "123456");        bs.find();

        logger.info("--------------------------------------");

        WorkService ws = LogInvoHandler.getProxyInstance(WorkServiceImpl.class);        ws.work();        ws.sleep();

        logger.info("--------------------------------------");

        BussinessService bss = LogInvoHandler.getProxyInstance(BussinessServiceImpl.class);        bss.login("lisi", "654321");        bss.find();

    }}以后需要添加新的业务逻辑XXXService，只需要调用

XXXService xs = LogInvoHandler.getProxyInstance(XXXServiceImpl.class);

即可。

也可以模仿Spring等框架的配置，把bean的类名配置在xml文件中，如：

<bean id="bussinessService" class="com.wangjie.aoptest2.service.impl.BussinessServiceImpl">

然后在java代码中解析xml，通过Class.forName("com.wangjie.aoptest2.service.impl.BussinessServiceImpl");获得Class对象

然后通过LogInvoHandler.getProxyInstance(Class.forName("com.wangjie.aoptest2.service.impl.BussinessServiceImpl"));获得代理对象Proxy

再使用反射去调用代理对象的方法。

 

运行结果如下：

九月 24, 2013 11:08:03 上午 com.wangjie.aoptest2.invohandler.LogInvoHandler invokeINFO: ____invoke method: login; args: [zhangsan, 123456]; return: login success九月 24, 2013 11:08:03 上午 com.wangjie.aoptest2.invohandler.LogInvoHandler invokeINFO: ____invoke method: find; args: null; return: find success九月 24, 2013 11:08:03 上午 com.wangjie.aoptest2.Test mainINFO: --------------------------------------九月 24, 2013 11:08:03 上午 com.wangjie.aoptest2.invohandler.LogInvoHandler invokeINFO: ____invoke method: work; args: null; return: work success九月 24, 2013 11:08:03 上午 com.wangjie.aoptest2.invohandler.LogInvoHandler invokeINFO: ____invoke method: sleep; args: null; return: sleep success九月 24, 2013 11:08:03 上午 com.wangjie.aoptest2.Test mainINFO: --------------------------------------九月 24, 2013 11:08:03 上午 com.wangjie.aoptest2.invohandler.LogInvoHandler invokeINFO: ____invoke method: login; args: [lisi, 654321]; return: login success九月 24, 2013 11:08:03 上午 com.wangjie.aoptest2.invohandler.LogInvoHandler invokeINFO: ____invoke method: find; args: null; return: find success

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