Exemple d'analyse de la façon dont Java utilise Future pour obtenir des résultats d'exécution multithread en temps opportun

import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
/**
 * 多线程执行，异步获取结果
 * 
 * @author i-clarechen
 *
 */
public class AsyncThread {
  public static void main(String[] args) {
    AsyncThread t = new AsyncThread();
    List<Future<String>> futureList = new ArrayList<Future<String>>();
    t.generate(3, futureList);
    t.doOtherThings();
    t.getResult(futureList);
  }
  /**
   * 生成指定数量的线程，都放入future数组
   * 
   * @param threadNum
   * @param fList
   */
  public void generate(int threadNum, List<Future<String>> fList) {
    ExecutorService service = Executors.newFixedThreadPool(threadNum);
    for (int i = 0; i < threadNum; i++) {
      Future<String> f = service.submit(getJob(i));
      fList.add(f);
    }
    service.shutdown();
  }
  /**
   * other things
   */
  public void doOtherThings() {
    try {
      for (int i = 0; i < 3; i++) {
        System.out.println("do thing no:" + i);
        Thread.sleep(1000 * (new Random().nextInt(10)));
      }
    } catch (InterruptedException e) {
      e.printStackTrace();
    }
  }
  /**
   * 从future中获取线程结果，打印结果
   * 
   * @param fList
   */
  public void getResult(List<Future<String>> fList) {
    ExecutorService service = Executors.newSingleThreadExecutor();
    service.execute(getCollectJob(fList));
    service.shutdown();
  }
  /**
   * 生成指定序号的线程对象
   * 
   * @param i
   * @return
   */
  public Callable<String> getJob(final int i) {
    final int time = new Random().nextInt(10);
    return new Callable<String>() {
      @Override
      public String call() throws Exception {
        Thread.sleep(1000 * time);
        return "thread-" + i;
      }
    };
  }
  /**
   * 生成结果收集线程对象
   * 
   * @param fList
   * @return
   */
  public Runnable getCollectJob(final List<Future<String>> fList) {
    return new Runnable() {
      public void run() {
        for (Future<String> future : fList) {
          try {
            while (true) {
              if (future.isDone() && !future.isCancelled()) {
                System.out.println("Future:" + future
                    + ",Result:" + future.get());
                break;
              } else {
                Thread.sleep(1000);
              }
            }
          } catch (Exception e) {
            e.printStackTrace();
          }
        }
      }
    };
  }
}

do thing no:0
do thing no:1
do thing no:2
Future:java.util.concurrent.FutureTask@68e1ca74,Result:thread-0
Future:java.util.concurrent.FutureTask@3fb2bb77,Result:thread-1
Future:java.util.concurrent.FutureTask@6f31a24c,Result:thread-2

import java.util.Random;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.Callable;
import java.util.concurrent.CompletionService;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorCompletionService;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.LinkedBlockingDeque;
public class testCallable {
  public static void main(String[] args) {
    try {
      completionServiceCount();
    } catch (InterruptedException e) {
      e.printStackTrace();
    } catch (ExecutionException e) {
      e.printStackTrace();
    }
  }
  /**
   * 使用completionService收集callable结果
   * @throws ExecutionException 
   * @throws InterruptedException 
   */
  public static void completionServiceCount() throws InterruptedException, ExecutionException {
    ExecutorService executorService = Executors.newCachedThreadPool();
    CompletionService<Integer> completionService = new ExecutorCompletionService<Integer>(
        executorService);
    int threadNum = 5;
    for (int i = 0; i < threadNum; i++) {
      completionService.submit(getTask(i));
    }
    int sum = 0;
    int temp = 0;
    for(int i=0;i<threadNum;i++){
      temp = completionService.take().get();
      sum += temp;
      System.out.print(temp + "\t");
    }
    System.out.println("CompletionService all is : " + sum);
    executorService.shutdown();
  }
  public static Callable<Integer> getTask(final int no) {
    final Random rand = new Random();
    Callable<Integer> task = new Callable<Integer>() {
      @Override
      public Integer call() throws Exception {
        int time = rand.nextInt(100)*100;
        System.out.println("thead:"+no+" time is:"+time);
        Thread.sleep(time);
        return no;
      }
    };
    return task;
  }
}

thead:0 time is:4200
thead:1 time is:6900
thead:2 time is:2900
thead:3 time is:9000
thead:4 time is:7100
  0  1  4  3  CompletionService all is : 10