並法包信號量的使用

https://www.cnblogs.com/amosli/p/3687776.html

 

/** 
* @ClassName: SemaPhoreTest 
* @Description: 線程通信中的"信號燈"
* @author: amosli
* @email:[email protected]
* @date Apr 25, 2014 12:06:22 AM  
*/
public class SemaPhoreTest {
    public static void main(String[] args) {
        ExecutorService threadPool = Executors.newCachedThreadPool();
        
        final Semaphore semaphore=new Semaphore(3);
        for(int i=0;i<10;i++){
            threadPool.execute(new Runnable() {
                public void run() {
                    try {
                        semaphore.acquire();//獲取一個可用的permits
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                    System.out.println("線程 " + Thread.currentThread().getName()+" 已進入.  " + "目前已經有"+(3-semaphore.availablePermits())+" 個線程進入");
                    try {
                        Thread.sleep(new Random().nextInt(1000));
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    System.out.println("線程 "+Thread.currentThread().getName()+ " 即將離開...");
                    semaphore.release();//釋放一個線程
                    System.out.println("線程 "+Thread.currentThread().getName()+ " 已離開.  當前有"+(3-semaphore.availablePermits())+"併發");
                }
            });
        }
    }
}