java如何中断ExecutorService的线程

Question

使用Executors.newSingleThreadExecutor()返回的ExecutorService时，如何中断它

Answer 1

为了做到这一点，您需要将^{}任务ExecutorService，而不是调用execute()。执行此操作时，将返回一个Future，可用于操作计划任务。特别是，您可以在关联的Future上调用^{}来中断当前正在执行的任务（如果任务尚未开始运行，则完全跳过执行）

顺便说一下，^{}返回的对象实际上是一个ExecutorService

Answer 2

一种合适的方法是为executorservice定制/注入ThreadFactory，在线程工厂中，创建线程的句柄，然后安排一些任务来中断感兴趣的线程

ThreadFactory中被覆盖的方法“newThread”的演示代码部分：

ThreadFactory customThreadfactory new ThreadFactory() {

            public Thread newThread(Runnable runnable) {
                final Thread thread = new Thread(runnable);
                if (namePrefix != null) {
                    thread.setName(namePrefix + "-" + count.getAndIncrement());
                }
                if (daemon != null) {
                    thread.setDaemon(daemon);
                }
                if (priority != null) {
                    thread.setPriority(priority);
                }

                scheduledExecutorService.schedule(new Callable<String>() {
                    public String call() throws Exception {
                        System.out.println("Executed!");
                        thread.interrupt();
                        return "Called!";

                    }
                },
                5,
                TimeUnit.SECONDS);

                return thread;
            }
        }

然后，您可以使用以下内容构建executorservice实例：

ExecutorService executorService = Executors.newFixedThreadPool(3,
        customThreadfactory);

然后在5秒后，一个中断信号将发送到executorservice中的线程

Answer 3

中断执行器的内部管理线程的另一种方法是在ExecutorService上调用shutdownNow(..)方法。但是，请注意，与@erickson的解决方案相反，这将导致整个ThreadPoolExecutor变得不适合进一步使用

我发现这种方法在不再需要ExecutorService的情况下特别有用，并且不需要对Future实例进行监视（应用程序的exit(..)方法就是一个很好的例子）

来自Java文档的相关信息：

Attempts to stop all actively executing tasks, halts the processing of waiting tasks, and returns a list of the tasks that were awaiting execution.

There are no guarantees beyond best-effort attempts to stop processing actively executing tasks. For example, typical implementations will cancel via Thread.interrupt, so any task that fails to respond to interrupts may never terminate.