CountDownLatch 协调线程

 1package cc.unmi.test.concurrent;
 2
 3import java.util.concurrent.CountDownLatch;
 4import java.util.concurrent.TimeUnit;
 5import java.util.logging.Level;
 6import java.util.logging.Logger;
 7
 8public class TestCountDownLatch {
 9
10    public static void main(String args[]) {
11       final CountDownLatch latch = new CountDownLatch(1);
12       Thread cacheService = new Thread(new Service("CacheService", 1000, latch));
13       Thread alertService = new Thread(new Service("AlertService", 1000, latch));
14
15       cacheService.start(); //separate thread will initialize CacheService
16       alertService.start(); //another thread for AlertService initialization
17
18       try{
19            latch.await(1000, TimeUnit.SECONDS);  //main thread is waiting on CountDownLatch to finish
20            System.out.println("All services are up, Application is starting now");
21       }catch(InterruptedException ie){
22
23       }
24    }
25
26}
27
28class Service implements Runnable{
29    private final String name;
30    private final int timeToStart;
31    private final CountDownLatch latch;
32
33    public Service(String name, int timeToStart, CountDownLatch latch){
34        this.name = name;
35        this.timeToStart = timeToStart;
36        this.latch = latch;
37    }
38
39    @Override
40    public void run() {
41        try {
42            Thread.sleep(timeToStart);
43        } catch (InterruptedException ex) {
44            Logger.getLogger(Service.class.getName()).log(Level.SEVERE, null, ex);
45        }
46        System.out.println( name + " is Up");
47        latch.countDown(); //reduce count of CountDownLatch by 1
48    }
49
50}