处理 子线程的返回值

package com.jimmy.Thread.ConcurrentTools;import static java.lang.System.out;import java.util.ArrayList;import java.util.List;import java.util.concurrent.ArrayBlockingQueue;import java.util.concurrent.BlockingQueue;import java.util.concurrent.Callable;import java.util.concurrent.CompletionService;import java.util.concurrent.ExecutorCompletionService;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;import java.util.concurrent.Future;import java.util.concurrent.FutureTask;import java.util.concurrent.TimeUnit;class TaskWithResult implements Callable<String>{  private int id;  public TaskWithResult(int id) throws InterruptedException  {    this.id = id;  }  @Override  public String call() throws Exception  {    TimeUnit.SECONDS.sleep(2);    return "result of TaskWithResult " + id;  }}public class CallableTest{  public static void main(String[] args) throws Exception  {//    test1();    test3();  }    /**   * 用 Join()方法等待所有子线程执行完，再收集执行结果   * @throws Exception   */  public static void test2() throws Exception  {    List<Thread> list = new ArrayList<Thread>();    ExecutorService exec = Executors.newCachedThreadPool();    ArrayList<FutureTask<String>> results = new ArrayList<FutureTask<String>>(); // Future    // 相当于是用来存放Executor执行的结果的一种容器    for (int i = 0; i < 10; i++) {      Callable<String> callable = new TaskWithResult(i);      FutureTask<String> futureTask = new FutureTask<String>(callable);      Thread thread = new Thread(futureTask);      thread.start();      results.add(futureTask);      list.add(thread);    }    long time0 = System.currentTimeMillis();    for(Thread thread:list){      thread.join();    }    out.println("共耗时:" + (System.currentTimeMillis()-time0));        String string = null;    for (FutureTask<String> fs : results) {      if(fs.isDone()){        try {          string = fs.get();        } catch (Exception e) {          e.printStackTrace();        }        out.println(string);      }else{        out.println("is not done!");      }    }    exec.shutdown();  }  /**   * 以BlockingQueue阻塞队列显式的接受子线程的返回值，操控灵活   * @throws Exception   */  public static void test1() throws Exception  {    ExecutorService pool = Executors.newCachedThreadPool();    BlockingQueue<Future<String>> blockingQueue = new ArrayBlockingQueue<Future<String>>(10);    CompletionService<String> service = new ExecutorCompletionService<String>(pool,blockingQueue);                                                                         // 相当于是用来存放Executor执行的结果的一种容器    for (int i = 0; i < 10; i++) {      Callable<String> callable = new TaskWithResult(i);      service.submit(callable);    }    String string = null;    int count = 0;    while(true){      Future<String> future = blockingQueue.take();      string = future.get();      count ++;      out.println(future.isDone() + "..value:===" + string);      if(count == 10){        break;      }    }    pool.shutdown();  }    /**   * 此种方式获取子线程的值是最为方便   * @throws Exception   */  public static void test3() throws Exception  {    ExecutorService pool = Executors.newCachedThreadPool();    CompletionService<String> service = new ExecutorCompletionService<String>(pool);                                                                         // 相当于是用来存放Executor执行的结果的一种容器    for (int i = 0; i < 10; i++) {      Callable<String> callable = new TaskWithResult(i);      service.submit(callable);    }        String string = null;    for (int i = 0; i < 10; i++) {      Future<String> future = service.take();//阻塞模式循环获取队列的值      string = future.get();      out.println(string);    }    pool.shutdown();  }}