【Java基础】java 获得本日，本周，本月的时间戳区间

   如果涉及到统计的话，可能会经常用到。很简单的基础知识。

1、getTimestampByOffsetDay

	public static long getTimestampByOffsetDay(int day){
		
		Calendar calendar = Calendar.getInstance();
		calendar.add(Calendar.DAY_OF_MONTH, day);
		calendar.set(Calendar.HOUR_OF_DAY, 0);
		calendar.set(Calendar.SECOND, 0);
		calendar.set(Calendar.MINUTE, 0);
		calendar.set(Calendar.MILLISECOND, 0);
		
		return calendar.getTimeInMillis();
	}

2、 getTodayTimestamp

	public static HashMap<String, Object> getTodayTimestamp(){
		
		HashMap<String, Object> hashMap = new HashMap<String, Object>();
		
		hashMap.put("startTime", getTimestampByOffsetDay(0));
		hashMap.put("endTime", getTimestampByOffsetDay(1));
		
		return hashMap;
	}

3、getWeekTimestamp

	public static HashMap<String, Object> getWeekTimestamp() {

		HashMap<String, Object> hashMap = new HashMap<String, Object>();

		Calendar calendar = Calendar.getInstance();

		hashMap.put(
				"startTime",
				getTimestampByOffsetDay(0 - calendar.get(Calendar.DAY_OF_WEEK) + 2));
		hashMap.put(
				"endTime",
				getTimestampByOffsetDay(calendar
						.getMaximum(Calendar.DAY_OF_WEEK)
						- calendar.get(Calendar.DAY_OF_WEEK) + 1));

		return hashMap;
	}

4、getMonthTimestamp

	public static HashMap<String, Object> getMonthTimestamp() {

		HashMap<String, Object> hashMap = new HashMap<String, Object>();

		Calendar calendar = Calendar.getInstance();

		hashMap.put(
				"startTime",
				getTimestampByOffsetDay(0 - calendar.get(Calendar.DAY_OF_MONTH) + 1));
		hashMap.put(
				"endTime",
				getTimestampByOffsetDay(calendar
						.getMaximum(Calendar.DAY_OF_MONTH)
						- calendar.get(Calendar.DAY_OF_MONTH)));

		return hashMap;
	}