ScheduledThreadPoolExecutor的使用

Java Executor框架提供了ThreadPoolExecutor类去执行Callable和Runnable任务，这样避免了大量的复杂代码的操作，但是有时你需要定时去执行你的任务，这个时候你就要使用ScheduledThreadPoolExecutor类了。

先写个基本的任务

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class Task implements Runnable
{
    private String name;
 
    public Task(String name) {
        this.name = name;
    }
     
    public String getName() {
        return name;
    }
 
    @Override
    public void run() 
    {
        try {
            System.out.println("Doing a task during : " + name + " - Time - " + new Date());
        } 
        catch (Exception e) {
            e.printStackTrace();
        }
    }
}

一段时间后执行

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public class ScheduledThreadPoolExecutorExample
{
    public static void main(String[] args) 
    {
        ScheduledExecutorService executor = Executors.newScheduledThreadPool(2);
        Task task1 = new Task ("Demo Task 1");
        Task task2 = new Task ("Demo Task 2");
         
        System.out.println("The time is : " + new Date());
         
        executor.schedule(task1, 5 , TimeUnit.SECONDS);
        executor.schedule(task2, 10 , TimeUnit.SECONDS);
         
        try {
              executor.awaitTermination(1, TimeUnit.DAYS);
        } catch (InterruptedException e) {
              e.printStackTrace();
        }
         
        executor.shutdown();
    }
}

The time is : Tue Jan 25 16:14:07 IST 2017
Doing a task during : Demo Task 1 - Time - Tue Jan 25 16:14:12 IST 2017
Doing a task during : Demo Task 2 - Time - Tue Jan 25 16:14:17 IST 2017

执行任务时间片的形式

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public class ScheduledThreadPoolExecutorExample
{
    public static void main(String[] args) 
    {
        ScheduledExecutorService executor = Executors.newScheduledThreadPool(1);
        Task task1 = new Task ("Demo Task 1");
         
        System.out.println("The time is : " + new Date());
         
        ScheduledFuture<?> result = executor.scheduleAtFixedRate(task1, 2, 5, TimeUnit.SECONDS);
         
        try {
            TimeUnit.MILLISECONDS.sleep(20000);
        } 
        catch (InterruptedException e) {
            e.printStackTrace();
        }
         
        executor.shutdown();
    }
}

Output:

The time is : Tue Jan 25 16:20:12 IST 2017
Doing a task during : Demo Task 1 - Time - Tue Jan 25 16:20:14 IST 2017
Doing a task during : Demo Task 1 - Time - Tue Jan 25 16:20:19 IST 2017
Doing a task during : Demo Task 1 - Time - Tue Jan 25 16:20:24 IST 2017
Doing a task during : Demo Task 1 - Time - Tue Jan 25 16:20:29 IST 2017