欢迎您访问程序员文章站本站旨在为大家提供分享程序员计算机编程知识!
您现在的位置是: 首页  >  IT编程

jdk自带定时器使用方法详解

程序员文章站 2023-12-05 20:01:40
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...

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。

package test;

import java.text.parseexception;
import java.text.simpledateformat;
import java.util.date;
import java.util.timer;
import java.util.timertask;

/**
 * jdk自带定时器
 * 
 * @author liutie
 *
 */
public class jdktimer {
  

  public static void main(string[] args) throws parseexception {
    //日期格式工具
    final simpledateformat sdf = new simpledateformat("yyyy-mm-dd hh:mm:ss");
    
    timer timer = new timer();
    // 10s后执行定时器,仅执行一次
    system.out.print(sdf.format(new date()));
    system.out.println("the timer one will be executed after 10 seconds...");
    long milliseconds = 10 * 1000;
    timer.schedule(new timertask() {

      @override
      public void run() {
        system.out.print(sdf.format(new date()));
        system.out.println("the timer one has finished execution");
      }
    }, milliseconds);
    
    //12秒后执行定时器,每1s执行一次
    system.out.print(sdf.format(new date()));
    system.out.println("the timer two will be executed after 12 seconds...");
    //启动后延迟时间
    long afterss = 12 * 1000;
    //执行周期
    long intervalss1 = 1 * 1000;
    timer.schedule(new timertask() {
      // 执行计数器
      int i = 0;

      @override
      public void run() {
        system.out.print(sdf.format(new date()));
        system.out.println("the timer two has execution " + (++i) + " timers");
        // 执行10次后关闭定时器
        if (i == 10) {
          this.cancel();
        }
      }
    }, afterss, intervalss1);
    
    
    // 指定时间执行定时器,仅执行一次
    system.out.print(sdf.format(new date()));
    system.out.println("the timer three will be executed at 2017-06-27 21:47:00...");
    date date = sdf.parse("2017-06-27 21:47:00");
    timer.schedule(new timertask() {

      @override
      public void run() {
        system.out.print(sdf.format(new date()));
        system.out.println("the timer three has finished execution");
      }
    }, date);
    
    // 从指定时间开始周期性执行
    system.out.print(sdf.format(new date()));
    system.out.println("the timer four will be executed at 2017-06-27 21:48:00...");
    // 执行间隔周期
    long intervalss = 1 * 1000;
    // 开始执行时间
    date begintime = sdf.parse("2017-06-27 21:48:00");
    timer.schedule(new timertask() {
      // 执行计数器
      int i = 0;

      @override
      public void run() {
        system.out.print(sdf.format(new date()));
        system.out.println("the timer four has execution " + (++i) + " timers");
        // 执行10次后关闭定时器
        if (i == 10) {
          this.cancel();
        }
      }
    }, begintime, intervalss);
  }

}

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

以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持。