Java实现流控-Semaphore

网上类似文章很多，不多说，直接上代码：

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1. /** 
2.  * 流控类（Semaphore实现） 
3.  *  
4.  * @author ln 
5.  * 
6.  */  
7. public class FlowControl {  
8.   
9.     /** 
10.      * 最大访问量 
11.      */  
12.     private static final int MAX_ACCESS_COUNT = 20;  
13.   
14.     /** 
15.      * 只能有MAX_ACCESS_COUNT个线程数同时访问 
16.      */  
17.     private static final Semaphore semaphore = new Semaphore(MAX_ACCESS_COUNT);  
18.   
19.     public static void main(String[] args) {  
20.         // 线程池  
21.         ExecutorService exec = Executors.newCachedThreadPool();  
22.   
23.         // 模拟30个客户端  
24.         for (int i = 0; i < 30; i++) {  
25.             Runnable run = new Runnable() {  
26.                 @Override  
27.                 public void run() {  
28.                     try {  
29.                         // 1秒钟内得不到许可，则丢弃访问。  
30.                         if (semaphore.tryAcquire(1, TimeUnit.SECONDS)) {  
31.                             System.out.println("正在执行...");  
32.                             //做一些事情...  
33.                             Thread.sleep(2 * 1000);  
34.                             System.out.println("执行完毕！");  
35.                         } else {  
36.                             System.out.println("访问被拒绝！！！");  
37.                         }  
38.                     } catch (InterruptedException e) {  
39.                         e.printStackTrace();  
40.                     } finally {  
41.                         // 执行完成，释放许可。  
42.                         semaphore.release();  
43.                     }  
44.                 }  
45.             };  
46.             exec.execute(run);  
47.         }  
48.   
49.         // 关闭线程池  
50.         exec.shutdown();  
51.     }  
52. }  

转自 ： https://blog.youkuaiyun.com/hyxhbj1/article/details/72847048