Executors Future Callable 使用场景实例

private List<PostResponse> createPostResponseList(Page<PostResponse> page,final String userId){ 
    if(page.getCount()==0||page==null||page.getList()==null){ 
      return null; 
    } 
    //获取帖子列表 
    List<PostResponse> circleResponseList = page.getList(); 
    int size=circleResponseList.size(); 
    ExecutorService commentPool = Executors.newFixedThreadPool(size); 
    ExecutorService supportPool = Executors.newFixedThreadPool(size); 
    try { 
      List<Future> commentFutureList = new ArrayList<Future>(size); 
      if (circleResponseList != null && circleResponseList.size() > 0) { 
        for (PostResponse postResponse : circleResponseList) { 
          final String circleId=postResponse.getId(); 
          final String postUserId=postResponse.getUserId(); 
          //查评论列表 
          Callable<List<CircleReviews>> callableComment = new Callable<List<CircleReviews>>() { 
            @Override
            public List<CircleReviews> call() throws Exception { 
              return circleReviewsBiz.getPostComments(circleId); 
            } 
          }; 
          Future f = commentPool.submit(callableComment); 
          commentFutureList.add(f); 
          //查点赞列表 
          Callable<List<CircleZan>> callableSupport = new Callable<List<CircleZan>>() { 
            @Override
            public List<CircleZan> call() throws Exception { 
              return circleZanBiz.findList(circleId); 
            } 
          }; 
          Future supportFuture = supportPool.submit(callableSupport); 
          commentFutureList.add(supportFuture); 
        } 
  
      } 
      // 获取所有并发任务的执行结果 
      int i = 0; 
      PostResponse temp = null; 
      for (Future f : commentFutureList) { 
        temp = circleResponseList.get(i); 
        temp.setCommentList((List<CircleReviews>) f.get(); 
        temp.setSupportList((List<CircleZan>) f.get(); 
        circleResponseList.set(i, temp); 
        i++; 
      } 
  
    } catch (Exception e) { 
      e.printStackTrace(); 
    } finally { 
      // 关闭线程池 
      commentPool.shutdown(); 
      supportPool.shutdown(); 
    } 
    return circleResponseList; 
}

import java.util.ArrayList; 
import java.util.List; 
import java.util.concurrent.*; 
 
public class CallableDemo{ 
    public static void main(String[] args){ 
        ExecutorService executorService = Executors.newCachedThreadPool(); 
        List<Future<String>> resultList = new ArrayList<Future<String>>(); 
 
        //创建10个任务并执行 
        for (int i = 0; i < 10; i++){ 
            //使用ExecutorService执行Callable类型的任务，并将结果保存在future变量中 
            Future<String> future = executorService.submit(new TaskWithResult(i)); 
            //将任务执行结果存储到List中 
            resultList.add(future); 
        } 
 
        //遍历任务的结果 
        for (Future<String> fs : resultList){ 
                try{ 
                    while(!fs.isDone);//Future返回如果没有完成，则一直循环等待，直到Future返回完成
                    System.out.println(fs.get());     //打印各个线程（任务）执行的结果 
                }catch(InterruptedException e){ 
                    e.printStackTrace(); 
                }catch(ExecutionException e){ 
                    e.printStackTrace(); 
                }finally{ 
                    //启动一次顺序关闭，执行以前提交的任务，但不接受新任务
                    executorService.shutdown(); 
                } 
        } 
    } 
} 
 
 
class TaskWithResult implements Callable<String>{ 
    private int id; 
 
    public TaskWithResult(int id){ 
        this.id = id; 
    } 
 
    /** 
     * 任务的具体过程，一旦任务传给ExecutorService的submit方法，
     * 则该方法自动在一个线程上执行
     */ 
    public String call() throws Exception {
        System.out.println("call()方法被自动调用！！！    " + Thread.currentThread().getName()); 
        //该返回结果将被Future的get方法得到
        return "call()方法被自动调用，任务返回的结果是：" + id + "    " + Thread.currentThread().getName(); 
    } 
}