深入理解JUC:第六章:Semaphore信號(hào)燈

理論:

Semaphore 是 synchronized 的加強(qiáng)版,作用是控制線程的并發(fā)數(shù)量

多個(gè)線程搶多個(gè)資源,下面案例是有六臺(tái)車(chē)搶三個(gè)停車(chē)位

使用Semaphore的代碼:

    public class Demo {
     
        public static void main(String[] args) throws Exception{
            //模擬三個(gè)停車(chē)位
            Semaphore semaphore = new Semaphore(3);
            //模擬六臺(tái)車(chē)
            for (int i = 1; i <= 6; i++) {
                new Thread(()->{
                    try {
                        semaphore.acquire();//減一
                        //semaphore.release();//加一
                        //semaphore.release(2);//加二
                        System.out.println(Thread.currentThread().getName()+"\t 搶到車(chē)位");
                        Thread.sleep(2000);
                        System.out.println(Thread.currentThread().getName()+"\t 停車(chē)2秒后離開(kāi)車(chē)位");
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }finally {
                        semaphore.release();
                    }
                },String.valueOf(i)).start();
            }
        }
    }

控制臺(tái):