jdk自帶定時器使用方法詳解

更新時間：2017年06月28日 10:54:56 作者：ToBeABetterPerson

這篇文章主要為大家詳細介紹了jdk自帶定時器的使用方法，具有一定的參考價值，感興趣的小伙伴們可以參考一下

首先看一下jdk自帶定時器：

一種工具，線程用其安排以后在后臺線程中執(zhí)行的任務?？砂才湃蝿請?zhí)行一次，或者定期重復執(zhí)行。與每個 Timer 對象相對應的是單個后臺線程，用于順序地執(zhí)行所有計時器任務。計時器任務應該迅速完成。如果完成某個計時器任務的時間太長，那么它會“獨占”計時器的任務執(zhí)行線程。因此，這就可能延遲后續(xù)任務的執(zhí)行，而這些任務就可能“堆在一起”，并且在上述不友好的任務最終完成時才能夠被快速連續(xù)地執(zhí)行。

schedule(TimerTask task,long delay) 安排在指定延遲后執(zhí)行指定的任務。
schedule(TimerTask task,Date time) 安排在指定的時間執(zhí)行指定的任務。如果此時間已過去，則安排立即執(zhí)行該任務。
schedule(TimerTask task, long delay, long period) 安排指定的任務從指定的延遲后開始進行重復的固定延遲執(zhí)行。如果由于任何原因（如垃圾回收或其他后臺活動）而延遲了某次執(zhí)行，則后續(xù)執(zhí)行也將被延遲
schedule(TimerTask task,Date firstTime,long period) 安排指定的任務在指定的時間開始進行重復的固定延遲執(zhí)行。如果由于任何原因（如垃圾回收或其他后臺活動）而延遲了某次執(zhí)行，則后續(xù)執(zhí)行也將被延遲。

package test;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Timer;
import java.util.TimerTask;

/**
 * jdk自帶定時器
 * 
 * @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后執(zhí)行定時器，僅執(zhí)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秒后執(zhí)行定時器，每1s執(zhí)行一次
    System.out.print(sdf.format(new Date()));
    System.out.println("the timer two will be executed after 12 seconds...");
    //啟動后延遲時間
    long afterSs = 12 * 1000;
    //執(zhí)行周期
    long intervalSs1 = 1 * 1000;
    timer.schedule(new TimerTask() {
      // 執(zhí)行計數(shù)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");
        // 執(zhí)行10次后關(guān)閉定時器
        if (i == 10) {
          this.cancel();
        }
      }
    }, afterSs, intervalSs1);
    
    
    // 指定時間執(zhí)行定時器，僅執(zhí)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);
    
    // 從指定時間開始周期性執(zhí)行
    System.out.print(sdf.format(new Date()));
    System.out.println("the timer four will be executed at 2017-06-27 21:48:00...");
    // 執(zhí)行間隔周期
    long intervalSs = 1 * 1000;
    // 開始執(zhí)行時間
    Date beginTime = sdf.parse("2017-06-27 21:48:00");
    timer.schedule(new TimerTask() {
      // 執(zhí)行計數(shù)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");
        // 執(zhí)行10次后關(guān)閉定時器
        if (i == 10) {
          this.cancel();
        }
      }
    }, beginTime, intervalSs);
  }

}

執(zhí)行結(jié)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

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