Java多线程系列（二十二）Semaphore使用

信号量用来控制能够同时访问的此时：

	Semaphore semphore = new Semaphore(3);
		Thread thread1 = new Thread(new Runnable() {
			
			@Override
			public void run() {
				while(true) {
					try {
						semphore.acquire();
					} catch (InterruptedException e2) {
						// TODO Auto-generated catch block
						e2.printStackTrace();
					}
					try {
						Random random = new Random();
						Thread.sleep(random.nextInt(1000)+1000);
					} catch (InterruptedException e1) {
						// TODO Auto-generated catch block
						e1.printStackTrace();
					}
					System.out.println("thread1 一次循环开始");
					try {
					} catch (Exception e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
					System.out.println("thread1 一次循环结束");
				}
			}
		});
		Thread thread2 = new Thread(new Runnable() {
			
			@Override
			public void run() {
				while(true) {
					try {
						semphore.acquire();
					} catch (InterruptedException e2) {
						// TODO Auto-generated catch block
						e2.printStackTrace();
					}
					try {
						Random random = new Random();
						Thread.sleep(random.nextInt(1000)+1000);
					} catch (InterruptedException e1) {
						// TODO Auto-generated catch block
						e1.printStackTrace();
					}
					System.out.println("thread2 一次循环开始");
					try {
					} catch (Exception e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
					System.out.println("thread2 一次循环结束");
				}
				
			}
		});
		thread1.start();
		thread2.start();

打印结果如下：

thread1 一次循环开始
thread1 一次循环结束
thread2 一次循环开始
thread2 一次循环结束
thread1 一次循环开始
thread1 一次循环结束

可以看到，在不释放信号量的情况下，最多进入三次。