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 {    @Override    public 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));    }    @Override    public 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 {    @Override    public 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>