Create a scheduled task thread pool
ScheduledExecutorService executorService = Executors.newScheduledThreadPool (4); // not recommended
// or
ScheduledExecutorService executorService = new ScheduledThreadPoolExecutor(4);// 推荐
Create a scheduled task
public interface ScheduledExecutorService extends ExecutorService { public ScheduledFuture<?> schedule(Runnable command, long delay, TimeUnit unit); public <V> ScheduledFuture<V> schedule(Callable<V> callable, long delay, TimeUnit unit);
public ScheduledFuture<?> scheduleAtFixedRate(Runnable command, long initialDelay, long period, TimeUnit unit);
public ScheduledFuture<?> scheduleWithFixedDelay(Runnable command, long initialDelay, long delay, TimeUnit unit); }
This example creates a scheduled task
Example 1: delay execution
package com.java.scheduled.task.pool; import java.text.SimpleDateFormat; import java.util.Date; import java.util.concurrent.ScheduledExecutorService; import java.util.concurrent.ScheduledThreadPoolExecutor; import java.util.concurrent.TimeUnit; public class ScheduledTaskDemo01 { public static void main(String[] args) { ScheduledExecutorService executorService = new ScheduledThreadPoolExecutor(4); SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); DATE DATE = new new DATE (); System.out.println ( "scheduling of tasks:" + sdf.format (DATE)); Long C1 = date.getTime (); the Runnable Runnable = () -> { DATE nowDate = new new a Date (); System.out.println ( "**** Scheduled tasks (1): [2 second delay execution]" ); System.out.println ( "real time mission:" + sdf.format (nowDate)); System.out.println ( "delay time:" + (nowDate.getTime () - C1) + "MS" ); }; executorService.schedule (Runnable,2 , TimeUnit.SECONDS); } }
Execution results are as follows:
The timing of implementation of tasks: 2019-05-28 12:10:46 **** Scheduled Tasks (1 ): [2 second delay enforcement of a real mission time: 2019-05-28 12:10:48 delay time : 2087ms
Example Two: deferred execution, returning a result
package com.java.scheduled.task.pool; import java.text.SimpleDateFormat; import java.util.Date; import java.util.concurrent.*; public class ScheduledTaskDemo02 { public static void main(String[] args) { ScheduledExecutorService executorService = Executors.newScheduledThreadPool(4); SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); Date date = new Date(); System.out.println("安排执行任务的时间："+sdf.format (DATE)); Long C2 = date.getTime (); a Callable <String> Callable = () -> { a Date nowDate = new new a Date (); System.out.println ( "**** Program Tasks ( 2): [2 second delay are performed to return the end result] " ); System.out.println ( " time actually perform the task: "+ sdf.format (nowDate)); System.out.println ( " delay time: "+ (nowDate.getTime () - c2) +" MS " ); Thread.sleep ( 1000 ); System.out.println ( " task is finished, the current time: "+ sdf.format ( new new a Date ())) ; return "success"; }; ScheduledFuture<String> scheduledFuture = executorService.schedule(callable, 2, TimeUnit.SECONDS); try { System.out.println("任务的执行结果："+scheduledFuture.get()); } catch (ExecutionException e1) { e1.printStackTrace(); } catch (InterruptedException e2) { e2.printStackTrace(); } } }
Execution results are as follows:
The timing of implementation of tasks: 2019-05-28 12:14:05 **** scheduled task (2 ): [2 second delay execution, execution returns to the end result] the actual time to perform tasks: 2019-05-2812: 14:07 delay time: 2072ms task is finished, the current time: 2019-05-28 12:14:08 execution results of the task: success
Example Three: delay task performed periodically +
package com.java.scheduled.task.pool; import java.text.SimpleDateFormat; import java.util.Date; import java.util.concurrent.Executors; import java.util.concurrent.ScheduledExecutorService; import java.util.concurrent.TimeUnit; public class ScheduledTaskDemo03 { public static void main(String[] args) { ScheduledExecutorService executorService = Executors.newScheduledThreadPool(4); SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); Date date = new new a Date (); System.out.println ( "scheduling of tasks:" + sdf.format (DATE)); Long C3 = date.getTime (); the Runnable Runnable = new new the Runnable () { Long exeTime = C3; @override public void RUN () { a Date nowDate = new new a Date (); System.out.println ( "--------------------------- -------------------------------------------------- --- " ); System.out.println ( " Scheduled tasks (3): [1 second delay the implementation of the first task, after performing the task every two seconds] " ); System.out.println ( "**** actual mission time:" + sdf.format (nowDate)); System.out.println ( "**** mission since the last time interval:" + ( nowDate.getTime () - exeTime) + "MS" ); the try { the Thread.sleep ( 4000 ); } the catch (InterruptedException E) {} exeTime = nowDate.getTime (); } }; executorService.scheduleAtFixedRate (Runnable, . 1, 2 , TimeUnit.SECONDS); } }
Execution results are as follows:
The timing of implementation of tasks: 2019-05-28 12:15:12 ---------------------------------- ---------------------------------------------- scheduled task ( 3 ): [1 second delay the implementation of the first task, after every two seconds to perform a task] actually perform the task **** time: 2019-05-28 12:15:13 **** from the last mission interval: 1003ms --------------------------------------------- ----------------------------------- scheduled task ( 3 ): [1 second delay the implementation of the first mission , after which a task every two seconds] **** actually perform the task time: 2019-05-28 12:15:17 **** from the last time interval to perform tasks: 4002ms ------ -------------------------------------------------- ------------------------ Scheduled tasks ( 3 ): [1 second delay the implementation of the first task, after every two seconds to perform a task] * *** the actual time to perform tasks: 2019-05-28 12:15:21 **** from the last time interval to perform tasks: 4001ms -------------------------------------------------- ------------------------------ scheduled task ( 3 ): [1 second delay the implementation of the first task, after every 2 seconds to perform a task] actually perform the task **** time: 2019-05-28 12:15:25 **** time interval from the last mission: 4002ms
Example 4: The initial delay + delay periodic tasks
package com.java.scheduled.task.pool; import java.text.SimpleDateFormat; import java.util.Date; import java.util.concurrent.Executors; import java.util.concurrent.ScheduledExecutorService; import java.util.concurrent.TimeUnit; public class ScheduledTaskDemo04 { public static void main(String[] args) { ScheduledExecutorService executorService = Executors.newScheduledThreadPool(4); SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); Date date = new new a Date (); System.out.println ( "scheduling of tasks:" + sdf.format (DATE)); Long C3 = date.getTime (); the Runnable Runnable = new new the Runnable () { Long exeTime = C3; @override public void RUN () { a Date nowDate = new new a Date (); System.out.println ( "--------------------------- -------------------------------------------------- --- " ); System.out.println ( " Scheduled tasks (4): [1 second delay the implementation of the first task, after performing the task every two seconds] " ); System.out.println ( "**** actual mission time:" + sdf.format (nowDate)); System.out.println ( "**** mission since the last time interval:" + ( nowDate.getTime () - exeTime) + "MS" ); the try { the Thread.sleep ( 2500 ); } the catch (InterruptedException E) {} exeTime = nowDate.getTime (); } }; executorService.scheduleWithFixedDelay (Runnable, . 1, 2 , TimeUnit.SECONDS); } }
Execution results are as follows:
The timing of implementation of tasks: 2019-05-28 12:16:56 ---------------------------------- ---------------------------------------------- scheduled task ( 4 ): [1 second delay the implementation of the first task, after every two seconds to perform a task] actually perform the task **** time: 2019-05-28 12:16:57 **** from the last mission interval: 1018ms --------------------------------------------- ----------------------------------- scheduled task ( 4 ): [1 second delay the implementation of the first mission , after which a task every two seconds] **** actually perform the task time: 2019-05-28 12:17:01 **** from the last time interval to perform tasks: 4504ms ------ -------------------------------------------------- ------------------------ Scheduled tasks ( 4 ): [1 second delay the implementation of the first task, after every two seconds to perform a task] * *** the actual time to perform tasks: 2019-05-28 12:17:06 **** from the last time interval to perform tasks: 4502ms -------------------------------------------------- ------------------------------ scheduled task ( 4 ): [1 second delay the implementation of the first task, after every 2 seconds to perform a task] actually perform the task **** time: 2019-05-28 12:17:10 **** time interval from the last mission: 4502ms