Semaphore关于抢车位例子

package com.test;

import java.util.Random;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Semaphore;

public class SemaphoreTest
{

	/**
	 * @param args
	 */
	public static void main(String[] args)
	{
		ExecutorService pool = Executors.newCachedThreadPool();
		final Semaphore sp = new Semaphore(3); // 3个车位
		for (int i = 0; i < 10; i++)
		{
			pool.execute(new Runnable()
			{
				public void run()
				{
					try
					{
						sp.acquire();
						System.out.println("小车：" + Thread.currentThread().getName()
								+ "已抢到车位,还有"+sp.availablePermits()+"个车位");
						Thread.sleep(new Random().nextInt(10000));
						sp.release();
						System.out.println("小车：" + Thread.currentThread().getName()
								+ "离开车位,还有"+sp.availablePermits()+"个车位");
					}
					catch (Exception e)
					{
						e.printStackTrace();
					}
				}
			});
		}
		pool.shutdown();
	}

}