Chapter 3, the static agent

Copyright: Reprinted please note the name of the source https://blog.csdn.net/meism5/article/details/90735087

In order not to modify the original ServiceImpl business code, and its expansion (statistics, printing and time-consuming) and interception (to determine whether login), you can use a proxy.

code show as below

1, let ServiceImpl original core business processing logic

package constxiong.cxproxy.chapter3.service;

import java.util.HashMap;
import java.util.Map;

/**
 * 服务接口实现
 * @author ConstXiong
 * @date 2019-05-29 11:02:15
 */
public class ServiceImpl implements Service {

	/**
	 * 登录
	 */
	@Override
	public boolean login(String username, String password) {
		simulateDaOperation(100);
		System.out.println("用户名：" + username + ", 密码：" + password + "  登录成功");
		return true;
	}

	/**
	 * 根据用户名获取用户信息
	 */
	@Override
	public Map<String, Object> getUserInfo(String username) {
		Map<String, Object> userInfo = new HashMap<String, Object>();
		simulateDaOperation(150);
		userInfo.put("username", username);
		userInfo.put("sex", "男");
		userInfo.put("age", 18);
		System.out.println("用户名：" + username + ", 获取用户信息：" + userInfo);
		return userInfo;
	}
	
	/**
	 * 模拟数据库操作，休眠
	 * @param millis 毫秒数
	 */
	private void simulateDaOperation(long millis) {
		try {
			Thread.sleep(millis);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
	}

}

 

2, a new class of agents, agent Service interface.

• Proxy holders of class interface to implement Service
• Agent login method, add the code printing capabilities and time-consuming
• Acting getUserinfo method, add a print time-consuming function code verify login

package constxiong.cxproxy.chapter3.proxy;

import java.util.Map;

import java.util.Random;

import constxiong.cxproxy.chapter3.service.Service;
import constxiong.cxproxy.chapter3.service.ServiceImpl;

/**
 * Service 接口的静态代理类
 * @author ConstXiong
 * @date 2019-06-02 00:10:02
 */
public class StaticServiceProxy implements Service {

	//持有Serrvice接口的实现类
	private Service service;
	
	public StaticServiceProxy() {
		service = new ServiceImpl(); 
	}
	
	@Override
	public boolean login(String username, String password) {
		long start = System.currentTimeMillis();//计时开始
		
		//调用 ServiceImpl 的登录方法
		boolean result = service.login(username, password);
		
		long end = System.currentTimeMillis();//计时结束
		System.out.println("耗时：" + (end - start) + "毫秒");//打印耗时
		
		return result;
	}

	@Override
	public Map<String, Object> getUserInfo(String username) {
		long start = System.currentTimeMillis();//计时开始
		
		Map<String, Object> result = null;
		if (checkIsLogined()) {//校验登录
			result = service.getUserInfo(username);//调用 ServiceImpl 的获取用户信息方法 
		}
		
		long end = System.currentTimeMillis();//计时结束
		System.out.println("耗时：" + (end - start) + "毫秒");//打印耗时
		
		return result;
	}
	
	/**
	 * 模拟  当前用户是否登录
	 */
	private boolean checkIsLogined() {
		Random r = new Random();
		int i = r.nextInt(10);
		if (i % 2 == 0) {
			System.out.println("已登录");
			return true;
		}
		System.out.println("未登录");
		return false;
	}

}

 

3, calling the test code

package constxiong.cxproxy.chapter3;

import constxiong.cxproxy.chapter3.proxy.StaticServiceProxy;
import constxiong.cxproxy.chapter3.service.Service;

/**
 * 测试类
 * @author ConstXiong
 * @date 2019-06-02 00:16:30
 */
public class Test {

	public static void main(String[] args) {
		Service service = new StaticServiceProxy();
		service.login("ConstXiong", "123456");
		service.getUserInfo("ConstXiong");
	}
	
}

The results of printing with in  Chapter 2, do not use a proxy  consistent results.

advantage:

• May not modify the original target class (refer to the ServiceImpl) code
• Can function to intercept and expansion in the proxy class

Disadvantages:

• Acting class needs to implement the same interface as the target class, will lead to a larger number of the proxy class, easy to maintain
• Once the interface method of increasing the target class and the need to maintain the proxy class

In view of these shortcomings, JDK dynamic proxies are available.

 

Complete source: https://github.com/ConstXiong/xtools     cxproxy project chapter3