Java多線程進一步的了解之------------線程池

public class ThreadPoolTest {
    public static void main(String[] args) {
        ExecutorService executorService = Executors.newCachedThreadPool();
        for (int i = 1; i <=10 ; i++) {
            final int task = i;
            executorService.execute(new Runnable() {
                @Override
                public void run() {
                    for (int j = 1; j <= 10; j++) {
                        try {
                            Thread.sleep(10);
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                        System.out.println(Thread.currentThread().getName() + "   is for    " + "   j=  " + j +"    task =   " + task);
                    }
                }
            });
        }
        //executorService.shutdown();
    }
}
代碼很簡單就不解釋了           

看一下第二種方式

public class SemaphoreTest {
    public static void main(String[] args) {
        ExecutorService service = Executors.newCachedThreadPool();
        final Semaphore s = new Semaphore(3);
        for (int i = 0; i < 10; i++) {// 開是個對象
            Runnable runnable = new Runnable() {
                @Override
                public void run() {
                    try {
                        s.acquire();// 判斷對象的信号燈，亮就代表有線程
                    }catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    System.out.println("線程" + Thread.currentThread() + "進入，目前已有" + s.availablePermits());
                    try {
                        Thread.sleep((long)(Math.random()*10000));
                    }catch (InterruptedException e){
                        e.printStackTrace();
                    }
                    System.out.println("線程"+Thread.currentThread()+"即将離開");
                    s.release();
                    System.out.println("線程"+Thread.currentThread()+"線程已離開,目前已有"+s.availablePermits());
                }
            };
            service.execute(runnable);// 把對象裝線程池
        }
    }
}