java定时任务调度

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package timer;  import java.text.SimpleDateFormat;  import java.util.Calendar;  import java.util.Date;  import java.util.Timer;      public class Timers {      private static final long PERIOD_DAY = 24 * 60 * 60 * 1000;//时间间隔(一天)               public static void timerExcute(){                 Timer timer = new Timer(); //定时器                 WeatherTimer weatherTimer=new WeatherTimer();//执行的任务                 Calendar calendar = Calendar.getInstance();                calendar.set(Calendar.HOUR_OF_DAY, 1); //凌晨1点                calendar.set(Calendar.MINUTE, 0);                calendar.set(Calendar.SECOND, 0);                Date date=calendar.getTime(); //第一次执行定时任务的时间                //如果第一次执行定时任务的时间 小于当前的时间                //此时要在 第一次执行定时任务的时间加一天，以便此任务在下个时间点执行。如果不加一天，任务会立即执行。                if (date.before(new Date())) {                    date = Timers.addDay(date, 1);                }                 System.out.println("data is = "+new SimpleDateFormat("yyyy-MM:dd HH:mm:ss").format(date));               timer.schedule(weatherTimer, date, PERIOD_DAY);//每天12点执行当前任务    }       // 增加或减少天数       public static Date addDay(Date date, int num) {           Calendar startDT = Calendar.getInstance();           startDT.setTime(date);           startDT.add(Calendar.DAY_OF_MONTH, num);           return startDT.getTime();       }               /***   *需集成当前时间任务类   */    public class WeatherTimer  extends Timer{                         public void run(){                                  }          }               public static void main(String[] args) {            Timers.timerExcute();       }  }