摘要：抽象類，實現了的接口。將任務封裝成提交任務主要方法在任務是否超時超時時間任務書用于存放結果的，先完成的放前面。

AbstractExecutorService抽象類，實現了ExecutorService的接口。

將任務封裝成FutureTask

protected  RunnableFuture newTaskFor(Runnable runnable, T value) {
    return new FutureTask(runnable, value);
}
protected  RunnableFuture newTaskFor(Callable callable) {
    return new FutureTask(callable);
}

提交任務

public Future submit(Runnable task) {
    if (task == null) throw new NullPointerException();
    RunnableFuture ftask = newTaskFor(task, null);
    execute(ftask);
    return ftask;
}
public  Future submit(Runnable task, T result) {
    if (task == null) throw new NullPointerException();
    RunnableFuture ftask = newTaskFor(task, result);
    execute(ftask);
    return ftask;
}
public  Future submit(Callable task) {
    if (task == null) throw new NullPointerException();
    RunnableFuture ftask = newTaskFor(task);
    execute(ftask);
    return ftask;
}

主要方法在doInvokeAny

//tasks任務
//timed是否超時
//nanos超時時間
private  T doInvokeAny(Collection> tasks,
                              boolean timed, long nanos)
    throws InterruptedException, ExecutionException, TimeoutException {
    if (tasks == null)
        throw new NullPointerException();
    int ntasks = tasks.size();//任務書
    if (ntasks == 0)
        throw new IllegalArgumentException();
    ArrayList> futures = new ArrayList>(ntasks);
    //用于存放結果的，先完成的放前面。所以第一個任務沒完成的時候，會繼續提交后續任務
    ExecutorCompletionService ecs =
        new ExecutorCompletionService(this);

    try {     
        //異常信息
        ExecutionException ee = null;
        //過期時間
        final long deadline = timed ? System.nanoTime() + nanos : 0L;
        Iterator> it = tasks.iterator();//獲取第一個任務
        提交任務
        futures.add(ecs.submit(it.next()));
        --ntasks;//因為提交了一個，任務數-1
        int active = 1;//正在執行的任務

        for (;;) {
            Future f = ecs.poll();
            if (f == null) {//第一個沒完成
                if (ntasks > 0) {//還有沒提交的任務
                    --ntasks;//任務數-1
                    futures.add(ecs.submit(it.next()));//提交任務
                    ++active;//正在執行的任務+1
                }
                else if (active == 0)//當前沒任務了，但是都失敗了，異常被捕獲了
                    break;
                else if (timed) {
                    f = ecs.poll(nanos, TimeUnit.NANOSECONDS);//等待
                    if (f == null)//返回空，超時拋出異常，結束
                        throw new TimeoutException();
                    nanos = deadline - System.nanoTime();//剩余時間
                }
                else
                    f = ecs.take();//阻塞等待獲取
            }
            if (f != null) {//說明已經執行完
                --active;//任務數-1
                try {
                    return f.get();//返回執行結果
                } catch (ExecutionException eex) {
                    ee = eex;
                } catch (RuntimeException rex) {
                    ee = new ExecutionException(rex);
                }
            }
        }

        if (ee == null)
            ee = new ExecutionException();
        throw ee;

    } finally {
        //取消其他任務，畢竟第一個結果已經返回了
        for (int i = 0, size = futures.size(); i < size; i++)
            futures.get(i).cancel(true);
    }
}

public  T invokeAny(Collection> tasks)
    throws InterruptedException, ExecutionException {
    try {
        return doInvokeAny(tasks, false, 0);
    } catch (TimeoutException cannotHappen) {
        assert false;
        return null;
    }
}

public  T invokeAny(Collection> tasks,
                       long timeout, TimeUnit unit)
    throws InterruptedException, ExecutionException, TimeoutException {
    return doInvokeAny(tasks, true, unit.toNanos(timeout));
}

返回所有任務的結果

public  List> invokeAll(Collection> tasks)
    throws InterruptedException {
    if (tasks == null)
        throw new NullPointerException();
    ArrayList> futures = new ArrayList>(tasks.size());//
    boolean done = false;
    try {
        for (Callable t : tasks) {//封裝任務，并提交
            RunnableFuture f = newTaskFor(t);
            futures.add(f);
            execute(f);
        }
        for (int i = 0, size = futures.size(); i < size; i++) {
            Future f = futures.get(i);
            if (!f.isDone()) {
                try {
                    f.get();//阻塞，等待結果
                } catch (CancellationException ignore) {
                } catch (ExecutionException ignore) {
                }
            }
        }
        done = true;
        return futures;
    } finally {
        if (!done)//有異常，取消
            for (int i = 0, size = futures.size(); i < size; i++)
                futures.get(i).cancel(true);
    }
}

public  List> invokeAll(Collection> tasks,
                                     long timeout, TimeUnit unit)
    throws InterruptedException {
    if (tasks == null)
        throw new NullPointerException();
    long nanos = unit.toNanos(timeout);
    ArrayList> futures = new ArrayList>(tasks.size());
    boolean done = false;
    try {
        for (Callable t : tasks)
            futures.add(newTaskFor(t));

        final long deadline = System.nanoTime() + nanos;
        final int size = futures.size();

        // Interleave time checks and calls to execute in case
        // executor doesn"t have any/much parallelism.
        
        for (int i = 0; i < size; i++) {
            execute((Runnable)futures.get(i));
            nanos = deadline - System.nanoTime();
            if (nanos <= 0L)
                return futures;//每個提交都要判斷，超時了返回Future
        }

        for (int i = 0; i < size; i++) {
            Future f = futures.get(i);
            if (!f.isDone()) {
                if (nanos <= 0L)
                    return futures;
                try {
                    f.get(nanos, TimeUnit.NANOSECONDS);
                } catch (CancellationException ignore) {
                } catch (ExecutionException ignore) {
                } catch (TimeoutException toe) {
                    return futures;
                }
                nanos = deadline - System.nanoTime();
            }
        }
        done = true;
        return futures;
    } finally {
        if (!done)
            for (int i = 0, size = futures.size(); i < size; i++)
                futures.get(i).cancel(true);
    }
}