java CountDownLatch 模拟用户并发请求

客官°小女子只卖身不卖艺 2023-10-17 10:28 59阅读 0赞

java.util.concurrent.CountDownLatch,一个同步辅助类，在完成一组正在其他线程中执行的操作之前，它允许一个或多个线程一直等待。

主要方法  
public CountDownLatch(int count);  
public void countDown();  
public void await() throws InterruptedException  
  
构造方法参数指定了计数的次数  
countDown方法，当前线程调用此方法，则计数减一  
awaint方法，调用此方法会一直阻塞当前线程，直到计时器的值为0

示例代码：模拟多用户请求

package com.settlement.concurrent;
    
    import java.text.SimpleDateFormat;
    import java.util.Date;
    import java.util.concurrent.CountDownLatch;
    
    import com.settlement.commons.utils.HttpRequest;
    
    
    /**
     * 模拟用户的并发请求，检测用户乐观锁的性能问题
     * 
     * @author zzg
     * @date 2017-02-10
     */
    public class ConcurrentTest {
    	final static SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); 
    	public static void main(String[] args){
    		CountDownLatch latch=new CountDownLatch(1);//模拟5人并发请求，用户钱包
    		
    		for(int i=0;i<5;i++){//模拟5个用户
    			AnalogUser analogUser = new AnalogUser("user"+i,"58899dcd-46b0-4b16-82df-bdfd0d953bfb","1","20.024",latch);
    			analogUser.start();
    		}
    		latch.countDown();//计数器減一  所有线程释放 并发访问。
    		System.out.println("所有模拟请求结束  at "+sdf.format(new Date()));  
    		
    	}
    	
    	static class AnalogUser extends Thread{
    		String workerName;//模拟用户姓名
    		String openId;
    		String openType;
    		String amount;
    		CountDownLatch latch;
    		
    		public AnalogUser(String workerName, String openId, String openType, String amount,
    				CountDownLatch latch) {
    			super();
    			this.workerName = workerName;
    			this.openId = openId;
    			this.openType = openType;
    			this.amount = amount;
    			this.latch = latch;
    		}
    
    		@Override
    		public void run() {
    			// TODO Auto-generated method stub
    			try {  
    				latch.await(); //一直阻塞当前线程，直到计时器的值为0  
    	        } catch (InterruptedException e) {  
    	            e.printStackTrace();  
    	        }  			
    			post();//发送post 请求  
    	       
    	       
    			
    		} 
    		
    		public void post(){
    			String result = "";
    			System.out.println("模拟用户： "+workerName+" 开始发送模拟请求  at "+sdf.format(new Date()));  
    			result = HttpRequest.sendPost("http://localhost:8080/Settlement/wallet/walleroptimisticlock.action", "openId="+openId+"&openType="+openType+"&amount="+amount);
    			System.out.println("操作结果："+result);
    			System.out.println("模拟用户： "+workerName+" 模拟请求结束  at "+sdf.format(new Date())); 
    			
    		}
    		
    		
    		
    		
    		
    	}
    
    }