已知时间毫秒值，得到N天前的时间

Question

例如：已知了2011-10-3 15:12:30 的毫秒值，要得到4天前9:00 的时间的毫秒值。

Answer 1

Calendar c=Calendar.getInstance();
System.out.println(c.getTime());
c.add(c.DATE, -4);
c.set(c.HOUR_OF_DAY, 9);
c.set(c.MINUTE, 0);
c.set(c.SECOND, 0);
System.out.println(c.getTime()+"--"+c.getTimeInMillis());

Answer 2

楼主同学自己查下Calendar的方法，一看就知道了。有个setTimeInMillis的方法。

Answer 3

public class TimeUtil { public static Long sendMessageTime(Long followTime, int day, int hour) { Calendar c = Calendar.getInstance();
c.setTimeInMillis(followTime);
c.add(Calendar.DATE, -day);
c.set(Calendar.HOUR_OF_DAY, hour);
c.set(Calendar.MINUTE, 0);
c.set(Calendar.SECOND, 0);
System.out.println(c.getTime() + "------------" + c.getTimeInMillis()); return c.getTimeInMillis();
}

/** 测试 */
public static void main(String[] args) {
Calendar c1 = Calendar.getInstance();
Long time = MessageTimeUtil.sendMessageTime(c1.getTimeInMillis(),20, 22);
System.out.println(time);
}
}

Answer 4

public class MessageTimeUtil { public static Long sendMessageTime(Long followTime, int day, int hour) { Calendar c = Calendar.getInstance();
c.setTimeInMillis(followTime);
c.add(Calendar.DATE, -day);
c.set(Calendar.HOUR_OF_DAY, hour);
c.set(Calendar.MINUTE, 0);
c.set(Calendar.SECOND, 0);
System.out.println(c.getTime() + "------------" + c.getTimeInMillis()); return c.getTimeInMillis();
}

/** 测试 */
public static void main(String[] args) {
Calendar c1 = Calendar.getInstance();
Long time = MessageTimeUtil.sendMessageTime(c1.getTimeInMillis(),20, 22);
System.out.println(time);
}
}