複製代碼代碼如下:
package com.yao;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Semaphore;
/**
* Java 5.0里新加了4個協調線程間進程的同步裝置，它們分別是：
* Semaphore, CountDownLatch, CyclicBarrier和Exchanger.
* 本例主要介紹Semaphore。
* Semaphore是用來管理一個資源池的工具，可以看成是個通行證，
* 線程要想從資源池拿到資源必須先拿到通行證，
* 如果線程暫時拿不到通行證，線程就會被阻斷進入等待狀態。
*/
public class MySemaphore extends Thread {
private int i;
private Semaphore semaphore;
public MySemaphore(int i,Semaphore semaphore){
this.i = i;
this.semaphore = semaphore;
}
public void run(){
if(semaphore.availablePermits() > 0){
System.out.println(""+i+"有空位： ");
}else{
System.out.println(""+i+"等待，沒有空位");
}
try {
semaphore.acquire();
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println(""+i+"獲得空位");
try {
Thread.sleep((int)Math.random()*10000);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println(""+i+"使用完畢");
semaphore.release();
}
public static void main(String[] args) {
Semaphore semaphore = new Semaphore(2);
ExecutorService service = Executors.newCachedThreadPool();
for(int i = 0 ;i<10 ; i++){
service.execute(new MySemaphore(i,semaphore));
}
service.shutdown();
semaphore.acquireUninterruptibly(2);
System.out.println("使用完畢，需要清掃了");
semaphore.release(2);
}
}