天开始,天结束时间;周开始,周结束时间;月开始,月结束时间

/**
	 * 一天的零时刻
	 * @throws ParseException 
	 */
	public static Date getDayZero(Date date) throws ParseException{
		//y----年,不要写Y了,否则用sdf.parse(timeStr)得到的时间意想不到
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd 00:00:00");
		String timeStr = sdf.format(date);
		return sdf.parse(timeStr);
	}
	/**
	 * 一天的开始时间
	 * @throws ParseException 
	 */
	public static void dayStat() throws ParseException{
		Date date = new Date();
		Date dayZero = getDayZero(date);
		long timeMills = dayZero.getTime();
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		String timeStr = sdf.format(dayZero);
		System.out.println("一天的开始时间: "+ timeStr+" 毫秒值为:  "+timeMills);
	}
	/**
	 * 一天的结束时间
	 * @throws ParseException 
	 */
	public static void dayEnd() throws ParseException{
		Date date = new Date();
		Date dayZero = getDayZero(date);
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd 00:00:00");
		Calendar c = Calendar.getInstance();
		c.setTime(dayZero);
		//往后翻一天
		c.add(Calendar.DAY_OF_MONTH, 1);
		Date timeEnd = c.getTime();
		String tEnd = sdf.format(timeEnd);
		System.out.println("一天的开始时间: "+tEnd);
	}
	/**
	 * 一周的开始时间,即星期天的00:00:00
	 */
	public static void weekStat(){
		Date date = new Date();
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd 00:00:00");
		Calendar c = Calendar.getInstance();
		int week = c.get(Calendar.DAY_OF_WEEK);
		c.add(Calendar.DAY_OF_WEEK,-week+1);
		Date timeEnd = c.getTime();
		String tEnd = sdf.format(timeEnd);
		System.out.println("周开始时间: "+tEnd);
	}
	/**
	 * 一周的结束时间,即下周一的00:00:00
	 */
	public static void weekEnd(){
		Date date = new Date();
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd 00:00:00");
		Calendar c = Calendar.getInstance();
		c.setTime(date);
		//当天是一周的第几天,星期天为第一天
		int n = c.get(Calendar.DAY_OF_WEEK);
		//往后翻8-n天,即为一周的结束时间,即下周天的00:00:00
		c.add(Calendar.DAY_OF_MONTH, 7-n+1);
		Date timeEnd = c.getTime();
		String tEnd = sdf.format(timeEnd);
		System.out.println("周结束时间: "+tEnd);
	}
	/**
	 * 一月的开始时间
	 */
	public static void monthStat(){
		Date date = new Date();
		//一月的开始时间,始终是01号00:00:00开始
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-01 00:00:00");
		System.out.println("月开始时间: "+sdf.format(date));
	}
	/**
	 * 一月的结束时间
	 * @throws ParseException 
	 */
	public static void monthEnd() throws ParseException{
		Date date = new Date();
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-01 00:00:00");
		Date time = sdf.parse(sdf.format(date));
		Calendar c = Calendar.getInstance();
		c.setTime(time);
        //往后翻一个月
		c.add(Calendar.MONTH, 1);
		Date timeEnd = c.getTime();
		String tEnd = sdf.format(timeEnd);
		System.out.println("月结束时间: "+tEnd);
	}