时间处理工具类

public class TimeUtil {
    public static final String YYYYMMDD        = "yyyyMMdd";
    public static final String YYYYMMDDHHMMSS  = "yyyyMMddHHmmss";
    public static final String YYYYMMDD_HHMMSS = "yyyyMMdd HHmmss";

    public static Date now() {
        Calendar calendar = Calendar.getInstance();
        return calendar.getTime();
    }

    /**
     * 当前时间n秒之前的时间
     *
     * @param seconds
     * @return
     */
    public static Date timeBeforeNow(int seconds) {
        Calendar calendar = Calendar.getInstance();
        calendar.add(Calendar.SECOND, -seconds);
        return calendar.getTime();
    }

    /**
     * 当前时间n秒之后的时间
     *
     * @param seconds
     * @return
     */
    public static Date timeAfterNow(int seconds) {
        Calendar calendar = Calendar.getInstance();
        calendar.add(Calendar.SECOND, seconds);
        return calendar.getTime();
    }

    /**
     * 获取n秒后的时间
     *
     * @param date
     * @param seconds
     * @return
     */
    public static Date timeAfterSeconds(Date date, int seconds) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        calendar.add(Calendar.SECOND, seconds);
        return calendar.getTime();
    }

    /**
     * 获取n天后的时间
     *
     * @param date
     * @param days
     * @return
     */
    public static Date timeAfterDays(Date date, int days) {
        return timeAfterSeconds(date, days * 24 * 3600);
    }

    /**
     * 指定时间的凌晨0点0分0秒
     *
     * @param date 指定时间
     * @return
     */
    public static Date zeroTimeOfDay(Date date) {
        Calendar c = Calendar.getInstance();
        c.setTime(date);
        c.set(Calendar.HOUR_OF_DAY, 0);
        c.set(Calendar.MINUTE, 0);
        c.set(Calendar.SECOND, 0);
        return c.getTime();
    }

    /**
     * 当天 00:00:00
     *
     * @return
     */
    public static Date zeroTimeOfDay() {
        return zeroTimeOfDay(new Date());
    }

    /**
     * 得到本月的第一天
     *
     * @return
     */
    public static Date getMonthFirstDay() {
        Calendar calendar = Calendar.getInstance();
        calendar.set(Calendar.DAY_OF_MONTH,
                calendar.getActualMinimum(Calendar.DAY_OF_MONTH));
        calendar.set(Calendar.HOUR_OF_DAY, 0);
        calendar.set(Calendar.MINUTE, 0);
        calendar.set(Calendar.SECOND, 0);
        return calendar.getTime();
    }

    /**
     * 得到本月的最后一天
     *
     * @return
     */
    public static Date getMonthLastDay() {
        Calendar calendar = Calendar.getInstance();
        calendar.set(Calendar.DAY_OF_MONTH,
                calendar.getActualMaximum(Calendar.DAY_OF_MONTH));
        return calendar.getTime();
    }

    /**
     * 当天23点59分59秒
     *
     * @param date
     * @return
     */
    public static Date endTimeOfDay(Date date) {
        Calendar c = Calendar.getInstance();
        c.setTime(date);
        c.set(Calendar.HOUR_OF_DAY, 23);
        c.set(Calendar.MINUTE, 59);
        c.set(Calendar.SECOND, 59);
        return c.getTime();
    }

    /**
     * 当天0点0分0秒
     *
     * @param date
     * @return
     */
    public static Date zeroTimeOfHour(Date date) {
        Calendar c = Calendar.getInstance();
        c.setTime(date);
        c.set(Calendar.MINUTE, 0);
        c.set(Calendar.SECOND, 0);
        return c.getTime();
    }

    /**
     * 对时间进行格式化 yyyy-MM-dd HH:mm:ss
     *
     * @param date
     * @return
     */
    public static String timeFormat(Date date) {
        return timeFormat(date, "yyyy-MM-dd HH:mm:ss");
    }

    /**
     * 当前时间 yyyy-MM-dd HH:mm:ss 格式的字符串
     *
     * @return
     */
    public static String nowString() {
        return timeFormat(now());
    }

    /**
     * 对时间进行格式化：年月日 yyyyMMdd
     *
     * @param date
     * @return
     */
    public static String timeFormat_yyyyMMdd(Date date) {
        return timeFormat(date, "yyyyMMdd");
    }

    /**
     * 对时间进行格式化
     *
     * @param date
     * @param format
     * @return
     */
    public static String timeFormat(Date date, String format) {
        if (date == null) {
            return "";
        }
        SimpleDateFormat formatter = new SimpleDateFormat(format);
        return formatter.format(date);
    }

    /**
     * 通过时间字符串获取Date
     *
     * @param timeStr 要求'yyyy-MM-dd HH:mm:ss'格式
     * @return
     */
    public static Date parse(String timeStr) {
        DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        try {
            return dateFormat.parse(timeStr);
        } catch (ParseException e) {
            return null;
        }
    }

    public static Date parseFormat(String timeStr, String format) {
        DateFormat dateFormat = new SimpleDateFormat(format);
        try {
            return dateFormat.parse(timeStr);
        } catch (ParseException e) {
            return null;
        }
    }

    /**
     * 将字符串格式yyyyMMdd的字符串转为日期，格式"yyyy-MM-dd"
     *
     * @param date 日期字符串
     * @return 返回格式化的日期
     * @throws ParseException 分析时意外地出现了错误异常
     */
    public static String strToDateFormat(String date) throws ParseException {
        SimpleDateFormat formatter = new SimpleDateFormat("yyyyMMddHHmmss");
        formatter.setLenient(false);
        Date newDate = formatter.parse(date);
        formatter = new SimpleDateFormat("yyyy-MM-dd  HH:mm:ss");
        return formatter.format(newDate);
    }

    /**
     * 计算两个日期之间相差的天数
     *
     * @param smdate 较小的时间
     * @param bdate  较大的时间
     * @return 相差天数
     * @throws ParseException
     */
    public static int daysBetween(Date smdate, Date bdate) {
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
        try {
            smdate = sdf.parse(sdf.format(smdate));
            bdate = sdf.parse(sdf.format(bdate));
        } catch (ParseException e) {
            return 0;
        }

        Calendar cal = Calendar.getInstance();
        cal.setTime(smdate);
        long time1 = cal.getTimeInMillis();
        cal.setTime(bdate);
        long time2 = cal.getTimeInMillis();
        long between_days = (time2 - time1) / (1000 * 3600 * 24);

        return (int) between_days;
    }

}