java编程思想笔记-并发之后台线程

package com.tij.chapter1;import java.util.concurrent.CountDownLatch;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;import java.util.concurrent.ThreadFactory;import java.util.concurrent.TimeUnit;/** *  * @author Allen * @date 2017-8-7 * */class DaemonThreadFactory implements ThreadFactory {    @Override    public Thread newThread(Runnable r) {        Thread thread = new Thread(r);        thread.setDaemon(true);        return thread;    }}class DaemonFromFactory implements Runnable {    private String threadName;    private CountDownLatch latch;    public DaemonFromFactory(int i, CountDownLatch latch) {        this.threadName = "thread-" + i;        this.latch = latch;    }    @Override    public void run() {            while (true) {                try {                    TimeUnit.MILLISECONDS.sleep(100);                    System.out.println(Thread.currentThread() + "--" + this);                    System.out.println("count--" + latch.getCount());                } catch (Exception e) {                    e.printStackTrace();                }finally{                    latch.countDown();                }            }    }    @Override    public String toString() {        return threadName;    }}public class DaemonTest {    public static void main(String[] args) {        CountDownLatch latch = new CountDownLatch(10);        ExecutorService exec = Executors                .newCachedThreadPool(new DaemonThreadFactory());        for (int i = 0; i < 10; i++) {            exec.execute(new DaemonFromFactory(i, latch));        }        System.out.println("All Threads Start");        try {            //latch.await(500, TimeUnit.MILLISECONDS);            latch.await();            //Thread.sleep(1000);        } catch (InterruptedException e) {            e.printStackTrace();        }        //主线程完成，则后台线程也全部中断        System.out.println("Task Stopped");    }}

后台线程的finally语句不会执行，因为父线程即main线程执行结束后，jvm会关闭所有线程，可以通过Executor来实现有序的关闭线程