Java dynamic proxy class implements simple example of log

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How does the Java dynamic proxy class implement simple logging? ? ?

Brief book address: http://www.jianshu.com/users/d38a3668be58/latest_articles

Solution to the problem

If you already have a certain java foundation

If you already know what a dynamic proxy is.

1. If the following is the real business class and its implementation class

[code]package com.hwy.test;

/**
 * Created by Ay on 2016/7/1.
 */
public interface BusinessClassService {

    public void doSomeThing();
}

Implementation class:

[code]package com.hwy.test;

/**
 * 业务类
 * Created by Ay on 2016/7/1.
 */
public class BusinessClassServiceImpl implements BusinessClassService{

    /** 执行某事 **/
    public void doSomeThing(){
        System.out.println("do something ......");
    }
}

2.The following is the log class and implementation class:

[code]package com.hwy.test;

import java.lang.reflect.Method;

/**
 * 日志类接口
 * Created by Ay on 2016/6/30.
 */
public interface MyLogger {

    /** 纪录进入方法时间 **/
    public void saveIntoMethodTime(Method method);

    /** 纪录退出方法时间**/
    public void saveOutMethodTime(Method method);
}

Implementation class:

[code]package com.hwy.test;

import java.lang.reflect.Method;

/**
 * 日志类实现
 * Created by Ay on 2016/6/30.
 */
public class MyLoggerImpl implements MyLogger {

    @Override
    public void saveIntoMethodTime(Method method) {
        System.out.println("进入" + method.getName()  +"方法时间为: " + System.currentTimeMillis());
    }

    @Override
    public void saveOutMethodTime(Method method) {
        System.out.println("退出" + method.getName() + "方法时间为：" + System.currentTimeMillis());

    }
}

3. The following is the handler implementation of the log class:

[code]package com.hwy.test;

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

/**
 * Created by Ay on 2016/6/30.
 */
public class MyLoggerHandler implements InvocationHandler {

    /** 原始对象 **/
    private Object objOriginal;

    /** 这里很关键 **/
    private MyLogger myLogger = new MyLoggerImpl();

    public MyLoggerHandler(Object obj){
        super();
        this.objOriginal = obj;
    }

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

        Object result = null;
        /** 日志类的方法 **/
        myLogger.saveIntoMethodTime(method);
        /** 调用代理类方法 **/
        result = method.invoke(this.objOriginal ,args);
        /** 日志类方法**/
        myLogger.saveOutMethodTime(method);

        return result;
    }

}

4. Finally, the test class:

[code]package com.hwy.test;

import java.lang.reflect.Proxy;

/**
 * Created by A on 2016/6/30.
 */
public class MyLoggerTest {

    public static void main(String[] args) {
        /** 实例化真实项目中业务类 **/
        BusinessClassService businessClassService = new BusinessClassServiceImpl();
        /** 日志类的handler **/
        MyLoggerHandler myLoggerHandler = new MyLoggerHandler(businessClassService);
        /** 获得代理类对象 **/
        BusinessClassService businessClass = (BusinessClassService)Proxy.newProxyInstance(businessClassService.getClass().getClassLoader(), businessClassService.getClass().getInterfaces(),myLoggerHandler);
        /** 执行代理类方法 **/
        businessClass.doSomeThing();

    }
}

5. Run MyLoggerTest class

[code]进入doSomeThing方法时间为: 1467326179684
do something ......
退出doSomeThing方法时间为：1467326179685

6. A few words:

[code]1)上面类中，类的初始化，基本可以利用spring配置到配置文件中
2)上面只是一个简单的例子而已

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