任务队列_单线程_异步

多任务--> 单线程处理  模拟打印机

比如：一台打印机接收到很多task ，但是打印机只有一个Thread。不能同时打印。

这个打印机，在打印的时候不能接收新任务！！！

import java.util.LinkedList;
public class Main {

    private static Thread thread;
    private static LinkedList<Runnable> list = new LinkedList<Runnable>();

    static int test = 0;

    public static void main(String[] args) {
        final long time = System.currentTimeMillis();
        for (int i = 0; i < 20; i++) {
            tastEvent(new Runnable() {
                public void run() {
                    try {
                        Thread.sleep(500);
                    } catch (InterruptedException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                    System.out.println("第" + (++test) + ("个任务  耗时:" + (System.currentTimeMillis() - time)));
                }

            });
        }
    }

    public static void tastEvent(Runnable r) {
        synchronized (list) {
            list.add(r);
        }
        if (thread == null) {
            thread = new Thread(run);
            thread.start();
        }

    }
    static Runnable run = new Runnable() {
        @Override
        public void run() {
            synchronized (list) {
                while (!list.isEmpty()) {
                    // new Thread(list.poll()).start();
                    list.poll().run();
                }
                thread = null;
            }
        }
    };

}