1 import java.util.Random;
2 import java.util.concurrent.Callable;
3 import java.util.concurrent.CompletionService;
4 import java.util.concurrent.ExecutionException;
5 import java.util.concurrent.ExecutorCompletionService;
6 import java.util.concurrent.ExecutorService;
7 import java.util.concurrent.Executors;
8 import java.util.concurrent.Future;
9
10 /**
11 * Callable与Future的应用
12 * Future取得的结果类型和Callable返回的结果类型必须一致，这是通过泛型来实现。
13 * Callable要采用ExecutorService的submit方法提交，返回的future对象可以取消任务。
14 * CompletionService用于提交一组Callable任务，其take方法返回已完成的一个Callable任务对应的Future对象。
15 * @author LiTaiQing
16 *
17 */
18 public class CallableAndFuture {
19
20 public static void main(String[] args) {
21
22 ExecutorService threadPool = Executors.newSingleThreadExecutor();
23 Future<String> future =
24 //有返回结果时用submit
25 threadPool.submit(new Callable<String>(){
26 @Override
27 public String call() throws Exception {
28 return "Hello";
29 }
30
31 });
32
33 System.out.println("等待结果");
34 try {
35 System.out.println("拿到结果" + future.get());
36 } catch (InterruptedException e) {
37 e.printStackTrace();
38 } catch (ExecutionException e) {
39 e.printStackTrace();
40 }
41
42 ExecutorService threadPool2 = Executors.newFixedThreadPool(10);
43 CompletionService<Integer> completionService = new ExecutorCompletionService<Integer>(threadPool2);
44 for(int i = 1; i < 10; i++){
45 final int seq = i;
46 completionService.submit(new Callable<Integer>(){
47 @Override
48 public Integer call() throws Exception {
49 Thread.sleep(new Random().nextInt(5000));
50 return seq;
51 }
52
53 });
54 }
55
56 for(int i = 0 ; i < 10; i++){
57 try {
58 System.out.println(completionService.take().get());
59 } catch (InterruptedException e) {
60 e.printStackTrace();
61 } catch (ExecutionException e) {
62 e.printStackTrace();
63 };
64 }
65
66 }
67
68 }
