在java.util.Timer.scheduleAtFixedRate(TimerTask timer, long delay, long period)
,delay
和period
有什么区别?
对于这些事情,请始终查看(Java SDK)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也应该自动显示给您)
所以延迟是从现在到第一次执行的时间,之后它再次执行每个周期毫秒。
另一个好方法是找出:使用两个不同的值来表示延迟和周期,以及一个TimerTask
,它只是在控制台上打印一行。然后看看会发生什么。
我们可以通过将延迟值作为sec / min
传递到延迟参数来在优先时间安排任务来启动任务。
运行RunTaskEvery2Seconds
程序一旦完成6秒,任务将被执行。延迟主要目的是延迟在优选时间执行的任务。
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