Java并发编程—如何取消定时任务

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
package com.dosrain.shunc.trial.schedule;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.concurrent.*;
public class PoolTest2 {
public static void main(String[] args) {
// 设置一个同步计算数，目的是让子线程完成工作后，主线程再继续工作。
// 因为这里只有一个子线程，所以设值为 1
CountDownLatch countDownLatch = new CountDownLatch(1);
// 创建线程池
ScheduledThreadPoolExecutor pool = new ScheduledThreadPoolExecutor(1);
// 创建固定时延的定时任务
ScheduledFuture<?> scheduledFuture = pool.scheduleWithFixedDelay(
new Task2(countDownLatch, 10)
, 0
, 2, TimeUnit.SECONDS);
try {
// 暂停主线程，等待同步计算数器归零后，主线程再继续工作
countDownLatch.await();
// 同步计数器已归零，说明定时任务已满足条件退出
// 所以取消定时任务
scheduledFuture.cancel(true);
} catch (InterruptedException e) {
e.printStackTrace();
}
// 关闭线程池
pool.shutdown();
}
}
class Task2 implements Runnable {
CountDownLatch countDownLatch;
private int counter;
public Task2(CountDownLatch countDownLatch, int counter) {
this.countDownLatch = countDownLatch;
this.counter = counter;
}
@Override
public void run() {
LocalDateTime localDateTime = LocalDateTime.now();
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
// 处理一些任务
System.out.println(localDateTime.format(dtf) + " [" + Thread.currentThread().getName() + "] " + counter);
if (counter-- == 0) {
// 判断达到停止任务的条件
countDownLatch.countDown();
}
}
}