首先看一下jdk自带定时器：
一种工具，线程用其安排以后在后台线程中执行的任务。可安排任务执行一次，或者定期重复执行。与每个 Timer 对象相对应的是单个后台线程，用于顺序地执行所有计时器任务。计时器任务应该迅速完成。如果完成某个计时器任务的时间太长，那么它会“独占”计时器的任务执行线程。因此，这就可能延迟后续任务的执行，而这些任务就可能“堆在一起”，并且在上述不友好的任务最终完成时才能够被快速连续地执行。
schedule(TimerTask task,long delay) 安排在指定延迟后执行指定的任务。
schedule(TimerTask task,Date time) 安排在指定的时间执行指定的任务。如果此时间已过去，则安排立即执行该任务。
schedule(TimerTask task, long delay, long period) 安排指定的任务从指定的延迟后开始进行重复的固定延迟执行。如果由于任何原因（如垃圾回收或其他后台活动）而延迟了某次执行，则后续执行也将被延迟
schedule(TimerTask task,Date firstTime,long period) 安排指定的任务在指定的时间开始进行重复的固定延迟执行。如果由于任何原因（如垃圾回收或其他后台活动）而延迟了某次执行，则后续执行也将被延迟。
1 package test;
2
3 import java.text.ParseException;
4 import java.text.SimpleDateFormat;
5 import java.util.Date;
6 import java.util.Timer;
7 import java.util.TimerTask;
8
9 /**
10 * jdk自带定时器
11 *
12 * @author LIUTIE
13 *
14 */
15 public class JDKTimer {
16
17
18 public static void main(String[] args) throws ParseException {
19 //日期格式工具
20 final SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
21
22 Timer timer = new Timer();
23 // 10s后执行定时器，仅执行一次
24 System.out.print(sdf.format(new Date()));
25 System.out.println("the timer one will be executed after 10 seconds...");
26 long milliseconds = 10 * 1000;
27 timer.schedule(new TimerTask() {
28
29 @Override
30 public void run() {
31 System.out.print(sdf.format(new Date()));
32 System.out.println("the timer one has finished execution");
33 }
34 }, milliseconds);
35
36 //12秒后执行定时器，每1s执行一次
37 System.out.print(sdf.format(new Date()));
38 System.out.println("the timer two will be executed after 12 seconds...");
39 //启动后延迟时间
40 long afterSs = 12 * 1000;
41 //执行周期
42 long intervalSs1 = 1 * 1000;
43 timer.schedule(new TimerTask() {
44 // 执行计数器
45 int i = 0;
46
47 @Override
48 public void run() {
49 System.out.print(sdf.format(new Date()));
50 System.out.println("the timer two has execution " + (++i) + " timers");
51 // 执行10次后关闭定时器
52 if (i == 10) {
53 this.cancel();
54 }
55 }
56 }, afterSs, intervalSs1);
57
58
59 // 指定时间执行定时器，仅执行一次
60 System.out.print(sdf.format(new Date()));
61 System.out.println("the timer three will be executed at 2017-06-27 21:47:00...");
62 Date date = sdf.parse("2017-06-27 21:47:00");
63 timer.schedule(new TimerTask() {
64
65 @Override
66 public void run() {
67 System.out.print(sdf.format(new Date()));
68 System.out.println("the timer three has finished execution");
69 }
70 }, date);
71
72 // 从指定时间开始周期性执行
73 System.out.print(sdf.format(new Date()));
74 System.out.println("the timer four will be executed at 2017-06-27 21:48:00...");
75 // 执行间隔周期
76 long intervalSs = 1 * 1000;
77 // 开始执行时间
78 Date beginTime = sdf.parse("2017-06-27 21:48:00");
79 timer.schedule(new TimerTask() {
80 // 执行计数器
81 int i = 0;
82
83 @Override
84 public void run() {
85 System.out.print(sdf.format(new Date()));
86 System.out.println("the timer four has execution " + (++i) + " timers");
87 // 执行10次后关闭定时器
88 if (i == 10) {
89 this.cancel();
90 }
91 }
92 }, beginTime, intervalSs);
93 }
94
95 }
执行结果
2017-06-27 21:46:24the timer one will be executed after 10 seconds... 2017-06-27 21:46:24the timer two will be executed after 12 seconds... 2017-06-27 21:46:24the timer three will be executed at 2017-06-27 21:47:00... 2017-06-27 21:46:24the timer four will be executed at 2017-06-27 21:48:00... 2017-06-27 21:46:34the timer one has finished execution 2017-06-27 21:46:36the timer two has execution 1 timers 2017-06-27 21:46:37the timer two has execution 2 timers 2017-06-27 21:46:38the timer two has execution 3 timers 2017-06-27 21:46:39the timer two has execution 4 timers 2017-06-27 21:46:40the timer two has execution 5 timers 2017-06-27 21:46:41the timer two has execution 6 timers 2017-06-27 21:46:42the timer two has execution 7 timers 2017-06-27 21:46:43the timer two has execution 8 timers 2017-06-27 21:46:44the timer two has execution 9 timers 2017-06-27 21:46:45the timer two has execution 10 timers 2017-06-27 21:47:00the timer three has finished execution 2017-06-27 21:48:00the timer four has execution 1 timers 2017-06-27 21:48:01the timer four has execution 2 timers 2017-06-27 21:48:02the timer four has execution 3 timers 2017-06-27 21:48:03the timer four has execution 4 timers 2017-06-27 21:48:04the timer four has execution 5 timers 2017-06-27 21:48:05the timer four has execution 6 timers 2017-06-27 21:48:06the timer four has execution 7 timers 2017-06-27 21:48:07the timer four has execution 8 timers 2017-06-27 21:48:08the timer four has execution 9 timers 2017-06-27 21:48:09the timer four has execution 10 timers
时间： 2024-08-09 14:36:55