摘要：抽象類(lèi)，實(shí)現(xiàn)了的接口。將任務(wù)封裝成提交任務(wù)主要方法在任務(wù)是否超時(shí)超時(shí)時(shí)間任務(wù)書(shū)用于存放結(jié)果的，先完成的放前面。

AbstractExecutorService抽象類(lèi)，實(shí)現(xiàn)了ExecutorService的接口。

將任務(wù)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(wù)

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(wù)
//timed是否超時(shí)
//nanos超時(shí)時(shí)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(wù)書(shū)
    if (ntasks == 0)
        throw new IllegalArgumentException();
    ArrayList> futures = new ArrayList>(ntasks);
    //用于存放結(jié)果的，先完成的放前面。所以第一個(gè)任務(wù)沒(méi)完成的時(shí)候，會(huì)繼續(xù)提交后續(xù)任務(wù)
    ExecutorCompletionService ecs =
        new ExecutorCompletionService(this);

    try {     
        //異常信息
        ExecutionException ee = null;
        //過(guò)期時(shí)間
        final long deadline = timed ? System.nanoTime() + nanos : 0L;
        Iterator> it = tasks.iterator();//獲取第一個(gè)任務(wù)
        提交任務(wù)
        futures.add(ecs.submit(it.next()));
        --ntasks;//因?yàn)樘峤涣艘粋€(gè)，任務(wù)數(shù)-1
        int active = 1;//正在執(zhí)行的任務(wù)

        for (;;) {
            Future f = ecs.poll();
            if (f == null) {//第一個(gè)沒(méi)完成
                if (ntasks > 0) {//還有沒(méi)提交的任務(wù)
                    --ntasks;//任務(wù)數(shù)-1
                    futures.add(ecs.submit(it.next()));//提交任務(wù)
                    ++active;//正在執(zhí)行的任務(wù)+1
                }
                else if (active == 0)//當(dāng)前沒(méi)任務(wù)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(shí)拋出異常，結(jié)束
                        throw new TimeoutException();
                    nanos = deadline - System.nanoTime();//剩余時(shí)間
                }
                else
                    f = ecs.take();//阻塞等待獲取
            }
            if (f != null) {//說(shuō)明已經(jīng)執(zhí)行完
                --active;//任務(wù)數(shù)-1
                try {
                    return f.get();//返回執(zhí)行結(jié)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(wù)，畢竟第一個(gè)結(jié)果已經(jīng)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(wù)的結(jié)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(wù)，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(jié)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(gè)提交都要判斷，超時(shí)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);
    }
}