在
java.util.Timer.scheduleAtFixedRate(TimerTask timer, long delay, long period)
中,delay
和 period
有什么区别?java.util.Timer.scheduleAtFixedRate(TimerTask timer, long delay, long period)
中,delay
和 period
有什么区别?对于这些事情,总是参考(Java SDK)的 JavaDocs: https://docs.oracle.com/javase/8/docs/api/java/util/Timer.html#scheduleAtFixedRate-java.util.TimerTask-long-long-
delay - delay in milliseconds before task is to be executed.
period - time in milliseconds between successive task executions.
您的IDE也应该会自动显示它
所以,delay是从现在到第一次执行的时间,之后每隔period毫秒再次执行。
另一个好方法是:使用两个不同的值作为delay和period,以及一个只在控制台打印一行的TimerTask
。然后看看会发生什么。
秒/分
的形式传递到延迟参数中,安排任务在首选时间开始执行。RunTaskEvery2Seconds
程序后,6秒钟后任务将被执行。
延迟的主要目的是延迟任务以在首选时间执行。package com.java.thread.task;
import java.util.Calendar;
import java.util.Date;
import java.util.Timer;
import java.util.TimerTask;
import lombok.extern.slf4j.Slf4j;
@Slf4j
public class RunTaskEvery2Seconds {
public static void main(String[] args) {
long timeIntervalForTaskOne = 2000;
int delaySeconds = 6*1000;//6 seconds
TimerTask taskOne = new TimerTask() {
@Override
public void run() {
// log.info("Running Task One Time: {}", new Date());
System.out.printf("Running Task One Time: %s", "call db", new Date() +"\n");
}
};
Timer timer = new Timer();
Calendar runningTime = Calendar.getInstance();
System.out.printf("Running Task One -> Actual starting Time:%s", runningTime.getTime() +"\n");
//updating delay time
runningTime.setTimeInMillis(runningTime.getTimeInMillis() + delaySeconds);
System.out.printf("Scheduled Running Task One will start at: %s", runningTime.getTime() +"\n");
System.out.println("Waiting for Schedule of Running Task One");
timer.scheduleAtFixedRate(taskOne, delaySeconds, timeIntervalForTaskOne);
}
}
控制台输出:
Running Task One -> Actual starting Time:Wed Mar 27 16:12:32 IST 2019
Scheduled Running Task One will start at: Wed Mar 27 16:12:38 IST 2019
Waiting for Schedule of Running Task One
Running Task One Time: Wed Mar 27 16:12:38 IST 2019
Running Task One Time: Wed Mar 27 16:12:40 IST 2019
Running Task One Time: Wed Mar 27 16:12:42 IST 2019