线程池 笔记

线程池

     一.线程池是线程的管理机制，主要解决两个问题:

         1:复用线程

        2:控制线程数量

   

        //创建线程池

        ExecutorService threadPool = Executors.newFixedThreadPool(2);

        for (int i = 0; i <5 ; i++) {

            //创建任务(Runnable)

            Runnable r = new Runnable() {

                public void run() {

                    try {

                        Thread t = Thread.currentThread();

                        System.out.println(t.getName()+":正在执行一个任务...");

                        Thread.sleep(5000);

                        System.out.println(t.getName()+":执行完毕....");

                    } catch (InterruptedException e) {

                        e.printStackTrace();

                    }

                }

            };

//实现线程任务

            threadPool.execute(r);

            System.out.println("交给线程池一个任务");

        }

        //shutdown()后，线程池处于关闭状态，此时不再接收新任务，等待现有任务都执行完毕后关闭

       //threadPool.shutdown();线程池会中断内部线程

        threadPool.shutdownNow();

        System.out.println("线程池关闭了");