从ThreadPoolTask​​Executor获得可调用或将Runnable强制转换为Callable

从ThreadPoolTask​​Executor获得可调用或将Runnable强制转换为Callable

正如在解释这个答案，你可能会通过控制

FutureTask

包裹的

Callable

通过手动创建它，并通过排队

execute

。否则，

submit

将您包装

Callable

到一个

ExecutorService

特定的对象中并将其放入队列中，从而使得无法

Callable

通过标准API
查询via的属性。

使用自定义

FutureTask

class MyFutureTask extends FutureTask<Integer> {    final IFormatter theCallable;    public MyFutureTask(IFormatter callable) {        super(callable);        theCallable=callable;    }    Long getOrderId() {        return theCallable.getOrderId();    }}

通过其入队

threadPoolExecutor.execute(new MyFutureTask(new Formatter(order)));

，

您可以查询队列中的订单ID：

public static boolean isEnqueued(ThreadPoolExecutor e, Long id) {    for(Object o: e.getQueue().toArray()) {        if(o instanceof MyFutureTask && Objects.equals(((MyFutureTask)o).getOrderId(), id)) return true;    }    return false;}

这适用于任何对象

ExecutorService

（假设它有一个队列）。如果仅使用一个

ThreadPoolExecutor

，则可以自定义

FutureTask

实例的创建（从Java6开始），而不是依靠提交者来创建它：

public class MyThreadPoolExecutor extends ThreadPoolExecutor {    public MyThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime,          TimeUnit unit, BlockingQueue<Runnable> workQueue) {        super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue);    }    public MyThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime,        TimeUnit unit, BlockingQueue<Runnable> workQueue, ThreadFactory threadFactory) {        super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, threadFactory);    }    public MyThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime,        TimeUnit unit, BlockingQueue<Runnable> workQueue,        RejectedExecutionHandler handler) {        super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, handler);    }    public MyThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime,        TimeUnit unit, BlockingQueue<Runnable> workQueue, ThreadFactory threadFactory,        RejectedExecutionHandler handler) {        super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, threadFactory, handler);    }    @Override    protected <T> RunnableFuture<T> newTaskFor(Callable<T> callable) {        if(callable instanceof IFormatter) return (FutureTask<T>)new MyFutureTask((IFormatter)callable);        return super.newTaskFor(callable);    }}

然后，使用实例

MyThreadPoolExecutor

代替实例的

ThreadPoolExecutor

每次提交

IFormatter

都会自动使用

MyFutureTask

代替standard进行包装

FutureTask

。缺点是，这仅适用于此特定

ExecutorService

方法，而通用方法会针对特殊处理生成未经检查的警告。