使用日期工具类：DateUtil

利用java开发，避免不了String、Date转换，前一天、后一天等问题。给出一个工具类，仅供学习交流。

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.Locale;
import java.util.logging.Level;
import java.util.logging.Logger;

public class DateUtil {

    public final static long   ONE_DAY_SECONDS       = 86400;
    public final static String shortFormat           = "yyyyMMdd";
    public final static String longFormat            = "yyyyMMddHHmmss";
    public final static String concurrentFormat      = "yyyyMMddHHmmssSSS";
    public final static String shortConcurrentFormat = "yyMMddHHmmssSSS";
    public final static String webFormat             = "yyyy-MM-dd";
    public final static String webMonthFormat        = "yyyy-MM";
    public final static String timeFormat            = "HH:mm:ss";
    public final static String monthFormat           = "yyyyMM";
    public final static String chineseDtFormat       = "yyyy年MM月dd日";
    public final static String chineseYMFormat       = "yyyy年MM月";
    public final static String newFormat             = "yyyy-MM-dd HH:mm:ss";
    public final static String noSecondFormat        = "yyyy-MM-dd HH:mm";
    public final static String MdFormat = "MM-dd";
    public final static long   ONE_DAY_MILL_SECONDS  = 86400000;

    public static DateFormat getNewDateFormat(String pattern) {
        DateFormat df = new SimpleDateFormat(pattern);

        df.setLenient(false);
        return df;
    }

    public static String format(Date date, String format) {
        if (date == null) {
            return null;
        }

        return new SimpleDateFormat(format).format(date);
    }

    public static String format(String dateStr, String oldFormat, String newFormat) {
        if (dateStr == null) {
            return null;
        }

        String result = null;
        DateFormat oldDateFormat = new SimpleDateFormat(oldFormat);
        DateFormat newDateFormat = new SimpleDateFormat(newFormat);

        try {
            Date date = oldDateFormat.parse(dateStr);
            result = newDateFormat.format(date);
        } catch (ParseException e) {
            e.printStackTrace();
        }

        return result;
    }

    public static Date parseDateNoTime(String sDate) {
        DateFormat dateFormat = new SimpleDateFormat(shortFormat);

        Date date = null;
        if ((sDate == null) || (sDate.length() < shortFormat.length())) {
            return null;
        }

        if (!StringUtil.isNumeric(sDate)) {
            return null;
        }

        try {
            date = dateFormat.parse(sDate);
        } catch (ParseException e) {
            e.printStackTrace();
        }

        return  date;
    }

    public static Date parseDateNoTime(String sDate, String format) throws ParseException {
        if (StringUtil.isBlank(format)) {
            throw new ParseException("Null format. ", 0);
        }

        DateFormat dateFormat = new SimpleDateFormat(format);

        if ((sDate == null) || (sDate.length() < format.length())) {
            throw new ParseException("length too little", 0);
        }

        return dateFormat.parse(sDate);
    }

    public static Date parseDateNoTimeWithDelimit(String sDate, String delimit)
                                                                               throws ParseException {
        sDate = sDate.replaceAll(delimit, "");

        DateFormat dateFormat = new SimpleDateFormat(shortFormat);

        if ((sDate == null) || (sDate.length() != shortFormat.length())) {
            throw new ParseException("length not match", 0);
        }

        return dateFormat.parse(sDate);
    }

    public static Date parseDateLongFormat(String sDate) {
        DateFormat dateFormat = new SimpleDateFormat(longFormat);
        Date d = null;

        if ((sDate != null) && (sDate.length() == longFormat.length())) {
            try {
                d = dateFormat.parse(sDate);
            } catch (ParseException ex) {
                return null;
            }
        }

        return d;
    }

    public static Date parseDateNewFormat(String sDate) {
        DateFormat dateFormat = new SimpleDateFormat(newFormat);
        Date d = null;
        dateFormat.setLenient(false);
        if ((sDate != null) && (sDate.length() == newFormat.length())) {
            try {
                d = dateFormat.parse(sDate);
            } catch (ParseException ex) {
                return null;
            }
        }
        return d;
    }

    public static Date parseDateNoSecondFormat(String sDate) {
        DateFormat dateFormat = new SimpleDateFormat(noSecondFormat);
        Date d = null;
        dateFormat.setLenient(false);
        if ((sDate != null) && (sDate.length() == noSecondFormat.length())) {
            try {
                d = dateFormat.parse(sDate);
            } catch (ParseException ex) {
                return null;
            }
        }
        return d;
    }

    public static Date parseDateWebFormat(String sDate) {
        DateFormat dateFormat = new SimpleDateFormat(webFormat);
        Date d = null;
        dateFormat.setLenient(false);
        if ((sDate != null) && (sDate.length() == webFormat.length())) {
            try {
                d = dateFormat.parse(sDate);
            } catch (ParseException ex) {
                return null;
            }
        }
        return d;
    }

    public static Date parseDateWebMonthFormat(String sDate) {
        DateFormat dateFormat = new SimpleDateFormat(webMonthFormat);
        Date d = null;
        dateFormat.setLenient(false);
        if ((sDate != null) && (sDate.length() == webMonthFormat.length())) {
            try {
                d = dateFormat.parse(sDate);
            } catch (ParseException ex) {
                return null;
            }
        }
        return d;
    }

    /**
     * 计算当前时间几小时之后的时间
     *
     * @param date
     * @param hours
     *
     * @return
     */
    public static Date addHours(Date date, long hours) {
        return addMinutes(date, hours * 60);
    }

    /**
     * 计算当前时间几分钟之后的时间
     *
     * @param date
     * @param minutes
     *
     * @return
     */
    public static Date addMinutes(Date date, long minutes) {
        return addSeconds(date, minutes * 60);
    }

    /**
     * @param date1
     * @param secs
     *
     * @return
     */

    public static Date addSeconds(Date date1, long secs) {
        return new Date(date1.getTime() + (secs * 1000));
    }

    /**
     * 判断输入的字符串是否为合法的小时
     *
     * @param hourStr
     *
     * @return true/false
     */
    public static boolean isValidHour(String hourStr) {
        if (!StringUtil.isEmpty(hourStr) && StringUtil.isNumeric(hourStr)) {
            int hour = new Integer(hourStr).intValue();

            if ((hour >= 0) && (hour <= 23)) {
                return true;
            }
        }

        return false;
    }

    /**
     * 判断输入的字符串是否为合法的分或秒
     *
     * @param minuteStr
     *
     * @return true/false
     */
    public static boolean isValidMinuteOrSecond(String str) {
        if (!StringUtil.isEmpty(str) && StringUtil.isNumeric(str)) {
            int hour = new Integer(str).intValue();

            if ((hour >= 0) && (hour <= 59)) {
                return true;
            }
        }

        return false;
    }

    /**
     * 取得新的日期
     *
     * @param date1
     *            日期
     * @param days
     *            天数
     *
     * @return 新的日期
     */
    public static Date addDays(Date date1, long days) {
        Calendar cal = Calendar.getInstance();
        cal.setTime(date1);
        cal.add(Calendar.DATE, (int) days);
        return cal.getTime();
    }

    public static String getTomorrowDateString(String sDate) throws ParseException {
        Date aDate = parseDateNoTime(sDate);

        aDate = addSeconds(aDate, ONE_DAY_SECONDS);

        return getDateString(aDate);
    }

    public static String getTomorrowDateNewFMTString(String sDate) throws ParseException {
        Date aDate = parseDateWebFormat(sDate);
        aDate = addDays(aDate, 1);
        return getWebDateString(aDate);
    }

    public static String getTomorrowDateNewFormatString(String sDate) throws ParseException {
        Date aDate = parseDateNewFormat(sDate);
        aDate = addDays(aDate, 1);
        return getWebDateString(aDate);
    }

    public static String getLongDateString(Date date) {
        DateFormat dateFormat = new SimpleDateFormat(longFormat);

        return getDateString(date, dateFormat);
    }

    public static String getNewFormatDateString(Date date) {
        DateFormat dateFormat = new SimpleDateFormat(newFormat);
        return getDateString(date, dateFormat);
    }

    public static String getWebFormatDateString(Date date) {
        DateFormat dateFormat = new SimpleDateFormat(webFormat);
        return getDateString(date, dateFormat);
    }

    public static String getConcurrentFormatDateString(Date date) {
        DateFormat dateFormat = new SimpleDateFormat(concurrentFormat);
        return getDateString(date, dateFormat);
    }

    public static String getDateString(Date date, DateFormat dateFormat) {
        if (date == null || dateFormat == null) {
            return null;
        }

        return dateFormat.format(date);
    }

    public static String getYesterDayDateString(String sDate) throws ParseException {
        Date aDate = parseDateNoTime(sDate);

        aDate = addSeconds(aDate, -ONE_DAY_SECONDS);

        return getDateString(aDate);
    }

    /**
     * @return 当天的时间格式化为"yyyyMMdd"
     */
    public static String getDateString(Date date) {
        DateFormat df = getNewDateFormat(shortFormat);

        return df.format(date);
    }

    public static String getWebDateString(Date date) {
        DateFormat dateFormat = getNewDateFormat(webFormat);

        return getDateString(date, dateFormat);
    }

    /**
     * 取得“X年X月X日”的日期格式
     *
     * @param date
     *
     * @return
     */
    public static String getChineseDateString(Date date) {
        DateFormat dateFormat = getNewDateFormat(chineseDtFormat);

        return getDateString(date, dateFormat);
    }

    public static String getTodayString() {
        DateFormat dateFormat = getNewDateFormat(shortFormat);

        return getDateString(new Date(), dateFormat);
    }

    public static String getTomorrowString() {
        DateFormat dateFormat = getNewDateFormat(shortFormat);

        return getDateString(DateUtil.addDays(new Date(), 1), dateFormat);
    }

    public static String getTimeString(Date date) {
        DateFormat dateFormat = getNewDateFormat(timeFormat);

        return getDateString(date, dateFormat);
    }

    public static String getBeforeDayString(int days) {
        Date date = new Date(System.currentTimeMillis() - (ONE_DAY_MILL_SECONDS * days));
        DateFormat dateFormat = getNewDateFormat(shortFormat);

        return getDateString(date, dateFormat);
    }

    /**
     * 取得两个日期间隔毫秒数（日期1-日期2）
     *
     * @param one
     *            日期1
     * @param two
     *            日期2
     *
     * @return 间隔秒数
     */
    public static long getDiffMillis(Date one, Date two) {
        Calendar sysDate = new GregorianCalendar();

        sysDate.setTime(one);

        Calendar failDate = new GregorianCalendar();

        failDate.setTime(two);
        return (sysDate.getTimeInMillis() - failDate.getTimeInMillis());
    }

    /**
     * 取得两个日期间隔秒数（日期1-日期2）
     *
     * @param one
     *            日期1
     * @param two
     *            日期2
     *
     * @return 间隔秒数
     */
    public static long getDiffSeconds(Date one, Date two) {
        Calendar sysDate = new GregorianCalendar();

        sysDate.setTime(one);

        Calendar failDate = new GregorianCalendar();

        failDate.setTime(two);
        return (sysDate.getTimeInMillis() - failDate.getTimeInMillis()) / 1000;
    }

    /**
     * 取得两个日期间隔分钟数（日期1-日期2）
     *
     * @param one
     *            日期1
     * @param two
     *            日期2
     *
     * @return 间隔秒数
     */
    public static long getDiffMinutes(Date one, Date two) {
        Calendar sysDate = new GregorianCalendar();

        sysDate.setTime(one);

        Calendar failDate = new GregorianCalendar();

        failDate.setTime(two);
        return (sysDate.getTimeInMillis() - failDate.getTimeInMillis()) / (60 * 1000);
    }

    /**
     * 取得两个日期的间隔天数
     *
     * @param one
     * @param two
     *
     * @return 间隔天数
     */
    public static long getDiffDays(Date one, Date two) {
        Calendar sysDate = new GregorianCalendar();

        sysDate.setTime(one);

        Calendar failDate = new GregorianCalendar();

        failDate.setTime(two);
        return (sysDate.getTimeInMillis() - failDate.getTimeInMillis()) / (24 * 60 * 60 * 1000);
    }

    /**
     * 取得两个日期相差的自然日
     *
     * @param date1
     * @param date2
     * @return
     */
    public static long getDiffNaturalDays(Date date1, Date date2) {

        Long diffDays = 0L;

        DateFormat dateFormat = new SimpleDateFormat(webFormat);

        //去掉时分秒
        String dateStr1 = dateFormat.format(date1);
        String dateStr2 = dateFormat.format(date2);

        try {
            diffDays = (dateFormat.parse(dateStr1).getTime() - dateFormat.parse(dateStr2).getTime()) / (24 * 60 * 60 * 1000);
        } catch (ParseException e) {
            e.printStackTrace();
        }

        return Math.abs(diffDays);
    }

    /**
     * 取得两个日期相差的自然日
     *
     * @param date1
     * @param date2
     * @return
     */
    public static long getDiffNaturalDayNotAbs(Date date1, Date date2) {

        Long diffDays = 0L;

        DateFormat dateFormat = new SimpleDateFormat(webFormat);

        //去掉时分秒
        String dateStr1 = dateFormat.format(date1);
        String dateStr2 = dateFormat.format(date2);

        try {
            diffDays = (dateFormat.parse(dateStr1).getTime() - dateFormat.parse(dateStr2).getTime()) / (24 * 60 * 60 * 1000);
        } catch (ParseException e) {
            e.printStackTrace();
        }

        return diffDays;
    }

    public static String getBeforeDayString(String dateString, int days) {
        Date date;
        DateFormat df = getNewDateFormat(shortFormat);

        try {
            date = df.parse(dateString);
        } catch (ParseException e) {
            date = new Date();
        }

        date = new Date(date.getTime() - (ONE_DAY_MILL_SECONDS * days));

        return df.format(date);
    }

    public static boolean isValidShortDateFormat(String strDate) {
        if (strDate.length() != shortFormat.length()) {
            return false;
        }

        try {
            Integer.parseInt(strDate); // ---- 避免日期中输入非数字 ----
        } catch (Exception NumberFormatException) {
            return false;
        }

        DateFormat df = getNewDateFormat(shortFormat);

        try {
            df.parse(strDate);
        } catch (ParseException e) {
            return false;
        }

        return true;
    }

    public static boolean isValidShortDateFormat(String strDate, String delimiter) {
        String temp = strDate.replaceAll(delimiter, "");

        return isValidShortDateFormat(temp);
    }

    /**
     * 判断表示时间的字符是否为符合yyyyMMddHHmmss格式
     *
     * @param strDate
     * @return
     */
    public static boolean isValidLongDateFormat(String strDate) {
        if (strDate.length() != longFormat.length()) {
            return false;
        }

        try {
            Long.parseLong(strDate); // ---- 避免日期中输入非数字 ----
        } catch (Exception NumberFormatException) {
            return false;
        }

        DateFormat df = getNewDateFormat(longFormat);

        try {
            df.parse(strDate);
        } catch (ParseException e) {
            return false;
        }

        return true;
    }

    /**
     * 判断表示时间的字符是否为符合yyyyMMddHHmmss格式
     *
     * @param strDate
     * @param delimiter
     * @return
     */
    public static boolean isValidLongDateFormat(String strDate, String delimiter) {
        String temp = strDate.replaceAll(delimiter, "");

        return isValidLongDateFormat(temp);
    }

    public static String getShortDateString(String strDate) {
        return getShortDateString(strDate, "-|/");
    }

    public static String getShortDateString(String strDate, String delimiter) {
        if (StringUtil.isBlank(strDate)) {
            return null;
        }

        String temp = strDate.replaceAll(delimiter, "");

        if (isValidShortDateFormat(temp)) {
            return temp;
        }

        return null;
    }

    public static String getShortFirstDayOfMonth() {
        Calendar cal = Calendar.getInstance();
        Date dt = new Date();

        cal.setTime(dt);
        cal.set(Calendar.DAY_OF_MONTH, 1);

        DateFormat df = getNewDateFormat(shortFormat);

        return df.format(cal.getTime());
    }

    public static String getWebTodayString() {
        DateFormat df = getNewDateFormat(webFormat);

        return df.format(new Date());
    }

    /**
     * 获取当月首日
     *
     * @return
     */
    public static String getWebFirstDayOfMonth() {
        Calendar cal = Calendar.getInstance();
        Date dt = new Date();

        cal.setTime(dt);
        cal.set(Calendar.DAY_OF_MONTH, 1);

        DateFormat df = getNewDateFormat(webFormat);

        return df.format(cal.getTime());
    }

    /**
     * 获取当月的总天数
     *
     * @return
     */
    public static int getDaysOfMonth() {
        Calendar cal = Calendar.getInstance(Locale.CHINA);
        int days = cal.getActualMaximum(Calendar.DATE);
        return days;
    }

    public static String convert(String dateString, DateFormat formatIn, DateFormat formatOut) {
        try {
            Date date = formatIn.parse(dateString);

            return formatOut.format(date);
        } catch (ParseException e) {
            return "";
        }
    }

    public static String convert2WebFormat(String dateString) {
        DateFormat df1 = getNewDateFormat(shortFormat);
        DateFormat df2 = getNewDateFormat(webFormat);

        return convert(dateString, df1, df2);
    }

    public static String convert2ChineseDtFormat(String dateString) {
        DateFormat df1 = getNewDateFormat(shortFormat);
        DateFormat df2 = getNewDateFormat(chineseDtFormat);

        return convert(dateString, df1, df2);
    }

    public static String convertFromWebFormat(String dateString) {
        DateFormat df1 = getNewDateFormat(shortFormat);
        DateFormat df2 = getNewDateFormat(webFormat);

        return convert(dateString, df2, df1);
    }

    public static boolean webDateNotLessThan(String date1, String date2) {
        DateFormat df = getNewDateFormat(webFormat);

        return dateNotLessThan(date1, date2, df);
    }

    /**
     * @param date1
     * @param date2
     * @param dateWebFormat2
     *
     * @return
     */
    public static boolean dateNotLessThan(String date1, String date2, DateFormat format) {
        try {
            Date d1 = format.parse(date1);
            Date d2 = format.parse(date2);

            if (d1.before(d2)) {
                return false;
            } else {
                return true;
            }
        } catch (ParseException e) {
            return false;
        }
    }

    public static String getEmailDate(Date today) {
        String todayStr;
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日HH:mm:ss");

        todayStr = sdf.format(today);
        return todayStr;
    }

    public static String getSmsDate(Date today) {
        String todayStr;
        SimpleDateFormat sdf = new SimpleDateFormat("MM月dd日HH:mm");

        todayStr = sdf.format(today);
        return todayStr;
    }

    public static String formatMonth(Date date) {
        if (date == null) {
            return null;
        }

        return new SimpleDateFormat(monthFormat).format(date);
    }

    /**
     * 获取系统日期的前一天日期，返回Date
     *
     * @return
     */
    public static Date getBeforeDate() {
        Date date = new Date();

        return new Date(date.getTime() - (ONE_DAY_MILL_SECONDS));
    }

    /**
     * 获得指定时间当天起点时间
     *
     * @param date
     * @return
     */
    public static Date getDayBegin(Date date) {
        DateFormat df = new SimpleDateFormat("yyyyMMdd");
        df.setLenient(false);

        String dateString = df.format(date);

        try {
            return df.parse(dateString);
        } catch (ParseException e) {
            return date;
        }
    }

    /**
     * 根据Date对象返回今天是星期几
     *
     * @param date
     * @return 1:星期日 2:星期一 3:星期二 4:星期三 5:星期四 6:星期五 7:星期六
     */
    public static int getWeekDayFromDateEntity(Date date) {

        Calendar calendar = Calendar.getInstance();// 获得一个日历
        calendar.setTime(date);
        int number = calendar.get(Calendar.DAY_OF_WEEK);// 星期表示1-7，是从星期日开始，

        return number;

    }

    /**
     * 判断参date上min分钟后，是否小于当前时间
     *
     * @param date
     * @param min
     * @return
     */
    public static boolean dateLessThanNowAddMin(Date date, long min) {
        return addMinutes(date, min).before(new Date());

    }

    public static boolean isBeforeNow(Date date) {
        if (date == null)
            return false;
        return date.compareTo(new Date()) < 0;
    }

    private static SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");

    // 获得当前月--开始日期
    public static Date getMinMonthDate(String date) {
        Calendar calendar = Calendar.getInstance();
        try {
            calendar.setTime(dateFormat.parse(date));
            calendar.set(Calendar.DAY_OF_MONTH, calendar.getActualMinimum(Calendar.DAY_OF_MONTH));
            return calendar.getTime();
        } catch (ParseException e) {
            return null;
        }
    }

    // 获得当前月--结束日期
    public static Date getMaxMonthDate(String date) {
        Calendar calendar = Calendar.getInstance();
        try {
            calendar.setTime(dateFormat.parse(date));
            calendar.set(Calendar.DAY_OF_MONTH, calendar.getActualMaximum(Calendar.DAY_OF_MONTH));
            return calendar.getTime();
        } catch (ParseException e) {
            return null;
        }
    }

    public static Date parseNoSecondFormat(String sDate) throws ParseException {
        DateFormat dateFormat = new SimpleDateFormat(noSecondFormat);

        if ((sDate == null) || (sDate.length() < noSecondFormat.length())) {
            throw new ParseException("length too little", 0);
        }

        if (!StringUtil.isNumeric(sDate)) {
            throw new ParseException("not all digit", 0);
        }

        return dateFormat.parse(sDate);
    }

    /*
    *
    * date日期转变成 制定格式字符串
    *
    */
    public static String convertDate2String(Date date, String time_pattern) {

        SimpleDateFormat sf = new SimpleDateFormat(time_pattern);

        return sf.format(date);

    }

    /**
     * 根据Date对象返回天
     *
     *
         * @param date
     */
    public static int getDayFromDateEntity(Date date) {
        Calendar calendar = Calendar.getInstance();// 获得一个日历
        calendar.setTime(date);
        int number = calendar.get(Calendar.DATE);// 星期表示1-7，是从星期日开始，
        return number;

    }

    public static int compare_date(String DATE1, String DATE2) {
        DateFormat df = new SimpleDateFormat("yyyy-MM");
        try {
            Date dt1 = df.parse(DATE1);
            Date dt2 = df.parse(DATE2);
            if (dt1.getTime() > dt2.getTime()) {
                //System.out.println("dt1 在dt2前");
                return 1;
            } else if (dt1.getTime() < dt2.getTime()) {
                //System.out.println("dt1在dt2后");
                return -1;
            } else {
                return 0;
            }
        } catch (Exception exception) {
            exception.printStackTrace();
        }
        return 0;
    }

    public static String getCurMonth() {
        return format(new Date(), webMonthFormat);
    }

    public static String getChineseYMString(String date) {

        SimpleDateFormat sdf = new SimpleDateFormat(chineseYMFormat);
        try {
            Date datea = sdf.parse(date);
            DateFormat dateFormat = getNewDateFormat(chineseYMFormat);
            return getDateString(datea, dateFormat);
        } catch (ParseException ex) {
            Logger.getLogger(DateUtil.class.getName()).log(Level.SEVERE, null, ex);
            return date;
        }

    }

    public static Date getPreMonthDate(String date) {
        SimpleDateFormat sdf = new SimpleDateFormat(webMonthFormat);
        try {
            Date datea = sdf.parse(date);
            Calendar cal = Calendar.getInstance();
            cal.setTime(datea);
            cal.add(Calendar.MONTH, -1);
            return cal.getTime();
        } catch (ParseException ex) {
            Logger.getLogger(DateUtil.class.getName()).log(Level.SEVERE, null, ex);
            return new Date();
        }

    }

    public static Date getNextMonthDate(String date) {
        SimpleDateFormat sdf = new SimpleDateFormat(webMonthFormat);
        try {
            Date datea = sdf.parse(date);
            Calendar cal = Calendar.getInstance();
            cal.setTime(datea);
            cal.add(Calendar.MONTH, 1);
            return cal.getTime();
        } catch (ParseException ex) {
            Logger.getLogger(DateUtil.class.getName()).log(Level.SEVERE, null, ex);
            return new Date();
        }
    }

    /**
     * 获取指定日期的当月的第一天
     *
     * @param date
     * @return
     */
    public static String getAssignedDateFirstDayOfMonth(Date date) {
        Calendar cal = Calendar.getInstance();

        cal.setTime(date);
        cal.set(Calendar.DAY_OF_MONTH, cal.getActualMinimum(Calendar.DAY_OF_MONTH));

        DateFormat df = getNewDateFormat(webFormat);

        return df.format(cal.getTime());
    }

    /**
     * 获取指定日期的当月的最后一天
     *
     * @param date
     * @return
     */
    public static String getAssignedDateLastDayOfMonth(Date date) {
        Calendar cal = Calendar.getInstance();

        cal.setTime(date);
        cal.set(Calendar.DAY_OF_MONTH, cal.getActualMaximum(Calendar.DAY_OF_MONTH));

        DateFormat df = getNewDateFormat(webFormat);

        return df.format(cal.getTime());
    }
        public static Date getNextDate(Date date) {
            try {
                Calendar calendar = Calendar.getInstance();
                calendar.setTime(date);
                calendar.add(Calendar.DAY_OF_MONTH, 1);
                Date date1 = new Date(calendar.getTimeInMillis());
                return date1;
            } catch (Exception ex) {
            Logger.getLogger(DateUtil.class.getName()).log(Level.SEVERE, null, ex);
            return date;
        }
        }

    /**
     * 根据年 月 获取对应的月份 天数
     * */
    public static int getDaysByYearMonth(int year, int month) {
        Calendar a = Calendar.getInstance();
        a.set(Calendar.YEAR, year);
        a.set(Calendar.MONTH, month - 1);
        a.set(Calendar.DATE, 1);
        a.roll(Calendar.DATE, -1);
        int maxDate = a.get(Calendar.DATE);
        return maxDate;
    }

}