java Timer定时任务。每天的某个时刻开启（亲测有效，直接运行）

这是管理类：

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import java.util.Calendar;
import java.util.Date;
import java.util.Timer;
import java.util.TimerTask;

/**
* Created by Administrator on 2017/9/29.
*/
public class TaskManager {
/**
* 开启任务
*/
//默认时间间隔一天
private static long PERIOD_TIME = 24 * 60 * 60 * 1000;
Log log = LogFactory.getLog(TaskManager.class);

public void startTask(TimerTask task, int dayInterval, int hour, int minute){
PERIOD_TIME =  dayInterval * 24 * 60 * 60 * 1000;
Calendar calendar = Calendar.getInstance();
calendar.set(Calendar.HOUR_OF_DAY, hour);
calendar.set(Calendar.MINUTE, minute);
calendar.set(Calendar.SECOND, 0);
//执行定时任务的时间
Date date=calendar.getTime();
//为了避免若容器启动的时间晚于定时时间，在重启容器的时候会立刻执行该任务
if (date.before(new Date())) {
date = this.addDay(date, 1);
}
Timer timer = new Timer();
//任务在指定的时间开始进行重复的固定延迟执行
timer.schedule(task,date);

}
// 增加或减少天数
public Date addDay(Date date, int num) {
Calendar startDT = Calendar.getInstance();
startDT.setTime(date);
startDT.add(Calendar.DAY_OF_MONTH, num);
return startDT.getTime();
}
}

这是监听：

import javax.servlet.ServletContextEvent;import javax.servlet.ServletContextListener;/*** Created by Administrator on 2017/9/29.*/public class RankTaskListener implements ServletContextListener {@Overridepublic void contextInitialized(ServletContextEvent servletContextEvent) {System.out.println("开启监听了.2点28准时启动...........");String day="1";String hour="14";String minute="28";new TaskManager().startTask(new RankTask(),Integer.parseInt(day), Integer.parseInt(hour), Integer.parseInt(minute));}@Overridepublic void contextDestroyed(ServletContextEvent servletContextEvent) {}}

这是定时任务：

import java.util.TimerTask;/*** Created by Administrator on 2017/9/29.*/public class RankTask extends TimerTask {@Overridepublic void run() {System.out.println("...............任务执行了.............");}}

web .xml配置监听：

<listener><listener-class>com.mytest.task.RankTaskListener</listener-class></listener>