如何在 Java 中暂停/重启 SingleThreadExecutor (ExecutorService)？

Question

我已经实现了一个 Singleton 类“SingleTaskExecutor”，它使用 SingleThreadExecutor 按顺序一次执行一个任务。此类用于按时间顺序执行异步数据库操作。一切正常。但是现在我们有一个用例，我们需要暂停此服务一段时间，执行一些操作，然后恢复服务。不确定如何暂停/恢复服务。这是我的代码：

public class SingleTaskExecutor {

    private SingleTaskExecutor() {}
    private final ExecutorService executor =   Executors.newSingleThreadExecutor();

    private static class LazyHolder {
        private static final SingleTaskExecutor instance = new SingleTaskExecutor(); 
    }

    public static SingleTaskExecutor getInstance() {
        return LazyHolder.instance;
    }

    public <T> Task<T> create(Callable<T> callable) {
        Task<T> task = new Task<T>() {
            @Override
            protected T call() throws Exception {
                return callable.call();
            }
        };
        return task;
    }

    public <T> T execute(Task<T> task) {
        return (T) executor.submit(task);
    }

    public void shutDown() {
        executor.shutdown();
    }

    public void awaitTermination() {
        try {
            executor.awaitTermination(5, TimeUnit.SECONDS);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    public void waitPlease() {
        try {
            Thread.currentThread().wait();
            //executor.wait();
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    public void resume() {
        Thread.currentThread().notifyAll();
        //executor.notifyAll();
    }
}

Answer 1

如果我的理解正确，您想暂停任务的执行，然后执行一些明确的任务，然后再继续执行。我实际上看到了以下解决方案：

private volatile boolean paused;

public <T> T execute(Task<T> task) {
    if(paused) {
        synchronized(this) {
            if(paused) {
                wait();
            }
        }
    }
    return (T) executor.submit(task);
}

public synchronized void waitPlease() {
    paused = true;
}

public synchronized void resume() {
    paused = false;
    notify();
}