Java 如何获取当前时间的前一段时间、以及给定一段时间的时间集合

1、相关日期处理

public class DateUtil {
	public static SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
	private static SimpleDateFormat sdf2=new SimpleDateFormat("yyyy-MM-dd-HH-mm-ss");
	public static SimpleDateFormat sdf3=new SimpleDateFormat("yyyy-MM-dd HH:mm");
	private static DecimalFormat decimalFormat=new DecimalFormat("#####0.## S");

	/**
	 * 获取当前时间的晚上23点59分59秒
	 *
	 * @param current
	 * @return
	 */
	public static Date getEndDate(Date current) {
		Calendar c = Calendar.getInstance();
		c.setTime(current);
		c.set(Calendar.HOUR_OF_DAY, 23);
		c.set(Calendar.MINUTE, 59);
		c.set(Calendar.SECOND, 59);
		return c.getTime();
	}

	/**
	 * 获取当前时间的0时0分0秒
	 * @param current
	 * @return
	 */
	public static Date getStartDate(Date current){
         Calendar calendarStart = Calendar.getInstance();
         calendarStart.setTime(current);
         calendarStart.set(calendarStart.get(Calendar.YEAR),
                         calendarStart.get(Calendar.MONTH),
                         calendarStart.get(Calendar.DATE),
                         0, 0, 0);
         current = calendarStart.getTime();
         return current;
	 }


	/**
	 * 获取当前月第一天
	 *
	 * @return
	 */
	public static Date getFirstDay() {
		Calendar c = Calendar.getInstance();
		c.add(Calendar.MONTH, 0);
		c.set(Calendar.DAY_OF_MONTH, 1);// 设置为1号,当前日期既为本月第一天
		return c.getTime();
	}

	/**
	 * 获取当前月最后一天
	 *
	 * @return
	 */
	public static Date getEndDay() {
		Calendar ca = Calendar.getInstance();
		ca.set(Calendar.DAY_OF_MONTH, ca.getActualMaximum(Calendar.DAY_OF_MONTH));
		return ca.getTime();
	}

	/**
	 * 获取当月天数
	 *
	 * @return
	 */
	public static int getCurrentMonthDay() {
		Calendar a = Calendar.getInstance();
		a.set(Calendar.DATE, 1);
		a.roll(Calendar.DATE, -1);
		int maxDate = a.get(Calendar.DATE);
		return maxDate;
	}


	/**
	 * 获取一段时间内所有的天数
	 *
	 * @param dBegin
	 * @param dEnd
	 * @return
	 */
	public static List<String> findDates(Date dBegin, Date dEnd) {
		SimpleDateFormat formart = new SimpleDateFormat("yyyy-MM-dd");
		List<String> lDate = new ArrayList<>();
		lDate.add(formart.format(dBegin));
		Calendar calBegin = Calendar.getInstance();
		calBegin.setTime(dBegin);
		Calendar calEnd = Calendar.getInstance();
		// 使用给定的 Date 设置此 Calendar 的时间
		calEnd.setTime(dEnd);
		// 测试此日期是否在指定日期之后
		while (dEnd.after(calBegin.getTime())) {
			// 根据日历的规则，为给定的日历字段添加或减去指定的时间量
			calBegin.add(Calendar.DAY_OF_MONTH, 1);
			lDate.add(formart.format(calBegin.getTime()));
		}
		return lDate;
	}

	public static String getNow() {
		return sdf.format(Calendar.getInstance().getTime());
	}

	public static String getNowId() {
		return sdf2.format(Calendar.getInstance().getTime());
	}

	/**
	 * 将 yyyy-MM-dd HH:mm 格式的字符串转化为Date
	 * @param dateString
	 * @return
	 */
	public static Date getDateByFormat3(String dateString){
		Date date=null;
		if(dateString==null) return null;
		try {
			date=sdf3.parse(dateString);
		} catch (ParseException e) {
			e.printStackTrace();
		}
		return date;
	}



	public static String getCronByDate(Date time){
		Calendar calendar=Calendar.getInstance();
		calendar.setTime(time);
		//0 15 10 * * ? 2005
		StringBuffer sb=new StringBuffer();
		sb.append(calendar.get(Calendar.SECOND)).append(" ");//秒
		sb.append(calendar.get(Calendar.MINUTE)).append(" ");//分
		sb.append(calendar.get(Calendar.HOUR_OF_DAY)).append(" ");//时
		sb.append(calendar.get(Calendar.DAY_OF_MONTH)).append(" ");//日期
		sb.append(calendar.get(Calendar.MONTH)+1).append(" ");//月份
		sb.append("?").append(" ");//星期
		sb.append(calendar.get(Calendar.YEAR));//年

		return sb.toString();
	}

    public static String secToTime(int time) {
        String timeStr = null;
        int hour = 0;
        int minute = 0;
        int second = 0;
        if (time <= 0)
            return "00:00:00";
        else {
            minute = time / 60;
            if (minute < 60) {
                second = time % 60;
                timeStr = "00:"+unitFormat(minute) + ":" + unitFormat(second);
            } else {
                hour = minute / 60;
                if (hour > 99)
                    return "99:59:59";
                minute = minute % 60;
                second = time - hour * 3600 - minute * 60;
                timeStr = unitFormat(hour) + ":" + unitFormat(minute) + ":" + unitFormat(second);
            }
        }
        return timeStr;
    }

    public static String msToSec(long time) {
    	return decimalFormat.format(time/1000f);
    }


    public static String unitFormat(int i) {
        String retStr = null;
        if (i >= 0 && i < 10)
            retStr = "0" + Integer.toString(i);
        else
            retStr = "" + i;
        return retStr;
    }


    public static void main(String[] args) {

   	}

    /**
     * 获取当前时间，指定前面多少小时的时间
     * @param ihour 前几个小时
     * @return
     */
    public static String getBeforeHourTime(int ihour){
        String returnstr = "";
        Calendar calendar = Calendar.getInstance();
        calendar.set(Calendar.HOUR_OF_DAY, calendar.get(Calendar.HOUR_OF_DAY) - ihour);
        SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        returnstr = df.format(calendar.getTime());
        return returnstr;
    }

    /**
     * 获取当前时间的前一天
     * @param date
     * @return
     */
    public static Date getPerDay(Date date) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        calendar.add(Calendar.DAY_OF_MONTH, -1);
        date = calendar.getTime();
        return date;
    }

	/**
	 * 获取当前时间的前三十天
	 * @param date
	 * @return
	 */
	public static Date getPer30Day(Date date) {
		Calendar calendar = Calendar.getInstance();
		calendar.setTime(date);
		calendar.add(Calendar.DAY_OF_MONTH, -30);
		date = calendar.getTime();
		return date;
	}

	/**
     * 获取当前时间的后一天
     * @param date
     * @return
     */
    public static Date getNextDay(Date date) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        calendar.add(Calendar.DAY_OF_MONTH, 1);
        date = calendar.getTime();
        return date;
    }

}