常用工具(十三) --DateUtil带详细注释


import java.sql.Timestamp;
import java.text.ParseException;
import java.text.ParsePosition;
import java.text.SimpleDateFormat;
import java.util.*;

public class DateUtil {
    
    

    /**
     * yyyy-MM-dd HH:mm:ss
     **/
    private static final ThreadLocal<SimpleDateFormat> FMT_YMDHMS = ThreadLocal.withInitial(() -> new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"));
    /**
     * yyyyMMddHHmmss
     **/
    public static final ThreadLocal<SimpleDateFormat> FMT_YMDHMS_N = ThreadLocal.withInitial(() -> new SimpleDateFormat("yyyyMMddHHmmss"));
    /**
     * yyyy-MM-dd HH:mm:ss.SSS
     **/
    public static final ThreadLocal<SimpleDateFormat> FMT_YMDHMSS = ThreadLocal.withInitial(() -> new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS"));
    /**
     * yyyyMMddHHmmssSSS
     **/
    public static final ThreadLocal<SimpleDateFormat> FMT_YMDHMSS_N = ThreadLocal.withInitial(() -> new SimpleDateFormat("yyyyMMddHHmmssSSS"));
    /**
     * yyyy-MM-dd
     **/
    public static final ThreadLocal<SimpleDateFormat> FMT_YMD = ThreadLocal.withInitial(() -> new SimpleDateFormat("yyyy-MM-dd"));
    /**
     * yyyyMMdd
     **/
    public static final ThreadLocal<SimpleDateFormat> FMT_YMD_N = ThreadLocal.withInitial(() -> new SimpleDateFormat("yyyyMMdd"));
    /**
     * 时间格式字符长度与时间格式的映射
     **/
    public static final HashMap<Integer, SimpleDateFormat> FMT_LENGTH_MAP = new HashMap<Integer, SimpleDateFormat>() {
    
    {
    
    
        put(19, FMT_YMDHMS.get());
        put(14, FMT_YMDHMS_N.get());
        //put(23, FMT_YMDHMSS.get());
        put(17, FMT_YMDHMSS_N.get());
        put(10, FMT_YMD.get());
        put(8, FMT_YMD_N.get());
        put(23, FMT_YMDHMSS.get());
    }};


    //============================借助Calendar类获取今天、昨天、本周、上周、本年及特定时间的开始时间和结束时间（返回类型为date类型）========================

    /**
     * 获取当天开始时间
     */
    public static Date getDayBegin() {
    
    
        Calendar cal = Calendar.getInstance();
        cal.set(Calendar.HOUR_OF_DAY, 0);//0点
        cal.set(Calendar.MINUTE, 0);//0分
        cal.set(Calendar.SECOND, 0);//0秒
        cal.set(Calendar.MILLISECOND, 0);//0毫秒
        return cal.getTime();
    }


    /**
     * 获取当天结束时间
     */
    public static Date getDayEnd() {
    
    
        Calendar cal = Calendar.getInstance();
        cal.set(Calendar.HOUR_OF_DAY, 23);//23点
        cal.set(Calendar.MINUTE, 59);//59分
        cal.set(Calendar.SECOND, 59);//59秒
        return cal.getTime();
    }


    /**
     * 获取昨天开始时间
     */
    public static Date getBeginDayOfYesterday() {
    
    
        Calendar cal = Calendar.getInstance();
        cal.setTime(getDayBegin());//当天开始时间
        cal.add(Calendar.DAY_OF_MONTH, -1);//当天月份天数减1
        return cal.getTime();
    }


    /**
     * 获取昨天结束时间
     */
    public static Date getEndDayOfYesterday() {
    
    
        Calendar cal = Calendar.getInstance();
        cal.setTime(getDayEnd());//当天结束时间
        cal.add(Calendar.DAY_OF_MONTH, -1);//当天月份天数减1
        return cal.getTime();
    }


    /**
     * 获取明天开始时间
     */
    public static Date getBeginDayOfTomorrow() {
    
    
        Calendar cal = Calendar.getInstance();
        cal.setTime(getDayBegin());//当天开始时间
        cal.add(Calendar.DAY_OF_MONTH, 1);//当天月份天数加1
        return cal.getTime();
    }


    /**
     * 获取明天结束时间
     */
    public static Date getEndDayOfTomorrow() {
    
    
        Calendar cal = Calendar.getInstance();
        cal.setTime(getDayEnd());//当天结束时间
        cal.add(Calendar.DAY_OF_MONTH, 1);//当天月份天数加1
        return cal.getTime();
    }


    /**
     * 获取某个日期的开始时间
     */
    public static Timestamp getDayStartTime(Date d) {
    
    
        Calendar calendar = Calendar.getInstance();
        if (null != d) {
    
    
            calendar.setTime(d);
        }
        calendar.set(calendar.get(Calendar.YEAR),
                calendar.get(Calendar.MONTH),
                calendar.get(Calendar.DAY_OF_MONTH), 0, 0, 0);
        calendar.set(Calendar.MILLISECOND, 0);
        return new Timestamp(calendar.getTimeInMillis());
    }


    /**
     * 获取某个日期的结束时间
     */
    public static Timestamp getDayEndTime(Date d) {
    
    
        Calendar calendar = Calendar.getInstance();
        if (null != d) {
    
    
            calendar.setTime(d);
        }
        calendar.set(calendar.get(Calendar.YEAR),
                calendar.get(Calendar.MONTH),
                calendar.get(Calendar.DAY_OF_MONTH), 23, 59, 59);
        calendar.set(Calendar.MILLISECOND, 999);
        return new Timestamp(calendar.getTimeInMillis());
    }


    /**
     * 获取本周的开始时间
     */
    @SuppressWarnings("unused")
    public static Date getBeginDayOfWeek() {
    
    
        Date date = new Date();
        if (date == null) {
    
    
            return null;
        }
        Calendar cal = Calendar.getInstance();
        cal.setTime(date);
        int dayOfWeek = cal.get(Calendar.DAY_OF_WEEK);
        if (dayOfWeek == 1) {
    
    
            dayOfWeek += 7;
        }
        cal.add(Calendar.DATE, 2 - dayOfWeek);
        return getDayStartTime(cal.getTime());
    }


    /**
     * 获取本周的结束时间
     */
    public static Date getEndDayOfWeek() {
    
    
        Calendar cal = Calendar.getInstance();
        cal.setTime(getBeginDayOfWeek());
        cal.add(Calendar.DAY_OF_WEEK, 6);
        Date weekEndSta = cal.getTime();
        return getDayEndTime(weekEndSta);
    }


    /**
     * 获取上周开始时间
     */
    @SuppressWarnings("unused")
    public static Date getBeginDayOfLastWeek() {
    
    
        Date date = new Date();
        if (date == null) {
    
    
            return null;
        }
        Calendar cal = Calendar.getInstance();
        cal.setTime(date);
        int dayofweek = cal.get(Calendar.DAY_OF_WEEK);
        if (dayofweek == 1) {
    
    
            dayofweek += 7;
        }
        cal.add(Calendar.DATE, 2 - dayofweek - 7);
        return getDayStartTime(cal.getTime());
    }


    /**
     * 获取上周的结束时间
     */
    public static Date getEndDayOfLastWeek() {
    
    
        Calendar cal = Calendar.getInstance();
        cal.setTime(getBeginDayOfLastWeek());
        cal.add(Calendar.DAY_OF_WEEK, 6);
        Date weekEndSta = cal.getTime();
        return getDayEndTime(weekEndSta);
    }


    /**
     * 获取今年是哪一年
     */
    public static Integer getNowYear() {
    
    
        Date date = new Date();
        GregorianCalendar gc = (GregorianCalendar) Calendar.getInstance();
        gc.setTime(date);
        return Integer.valueOf(gc.get(1));
    }


    /**
     * 获取本月是哪一月
     */
    public static int getNowMonth() {
    
    
        Date date = new Date();
        GregorianCalendar gc = (GregorianCalendar) Calendar.getInstance();
        gc.setTime(date);
        return gc.get(2) + 1;
    }


    /**
     * 获取本月的开始时间
     */
    public static Date getBeginDayOfMonth() {
    
    
        Calendar calendar = Calendar.getInstance();
        calendar.set(getNowYear(), getNowMonth() - 1, 1);
        return getDayStartTime(calendar.getTime());
    }


    /**
     * 获取本月的结束时间
     */
    public static Date getEndDayOfMonth() {
    
    
        Calendar calendar = Calendar.getInstance();
        calendar.set(getNowYear(), getNowMonth() - 1, 1);
        int day = calendar.getActualMaximum(5);
        calendar.set(getNowYear(), getNowMonth() - 1, day);
        return getDayEndTime(calendar.getTime());
    }


    /**
     * 获取上月的开始时间
     */
    public static Date getBeginDayOfLastMonth() {
    
    
        Calendar calendar = Calendar.getInstance();
        calendar.set(getNowYear(), getNowMonth() - 2, 1);
        return getDayStartTime(calendar.getTime());
    }


    /**
     * 获取上月的结束时间
     */
    public static Date getEndDayOfLastMonth() {
    
    
        Calendar calendar = Calendar.getInstance();
        calendar.set(getNowYear(), getNowMonth() - 2, 1);
        int day = calendar.getActualMaximum(5);
        calendar.set(getNowYear(), getNowMonth() - 2, day);
        return getDayEndTime(calendar.getTime());
    }


    /**
     * 获取本年的开始时间
     */
    public static Date getBeginDayOfYear() {
    
    
        Calendar cal = Calendar.getInstance();
        cal.set(Calendar.YEAR, getNowYear());
        cal.set(Calendar.MONTH, Calendar.JANUARY);
        cal.set(Calendar.DATE, 1);
        return getDayStartTime(cal.getTime());
    }


    /**
     * 获取本年的结束时间
     */
    public static Date getEndDayOfYear() {
    
    
        Calendar cal = Calendar.getInstance();
        cal.set(Calendar.YEAR, getNowYear());
        cal.set(Calendar.MONTH, Calendar.DECEMBER);
        cal.set(Calendar.DATE, 31);
        return getDayEndTime(cal.getTime());
    }


    /**
     * 两个日期相减得到的天数
     */
    public static int getDiffDays(Date beginDate, Date endDate) {
    
    
        if (beginDate == null || endDate == null) {
    
    
            throw new IllegalArgumentException("getDiffDays param is null!");
        }
        long diff = (endDate.getTime() - beginDate.getTime()) / (1000 * 60 * 60 * 24);
        int days = new Long(diff).intValue();
        return days;
    }


    /**
     * 两个日期相减得到的毫秒数
     */
    public static long dateDiff(Date beginDate, Date endDate) {
    
    
        long date1ms = beginDate.getTime();
        long date2ms = endDate.getTime();
        return date2ms - date1ms;
    }


    /**
     * 获取两个日期中的最大日起
     */
    public static Date max(Date beginDate, Date endDate) {
    
    
        if (beginDate == null) {
    
    
            return endDate;
        }
        if (endDate == null) {
    
    
            return beginDate;
        }
        if (beginDate.after(endDate)) {
    
    //beginDate日期大于endDate
            return beginDate;
        }
        return endDate;
    }


    /**
     * 获取两个日期中的最小日期
     */
    public static Date min(Date beginDate, Date endDate) {
    
    
        if (beginDate == null) {
    
    
            return endDate;
        }
        if (endDate == null) {
    
    
            return beginDate;
        }
        if (beginDate.after(endDate)) {
    
    
            return endDate;
        }
        return beginDate;
    }


    /**
     * 获取某月该季度的第一个月
     */
    public static Date getFirstSeasonDate(Date date) {
    
    
        final int[] SEASON = {
    
    1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4};
        Calendar cal = Calendar.getInstance();
        cal.setTime(date);
        int sean = SEASON[cal.get(Calendar.MONTH)];
        cal.set(Calendar.MONTH, sean * 3 - 3);
        return cal.getTime();
    }


    /**
     * 返回某个日期下几天的日期
     */
    public static Date getNextDay(Date date, int i) {
    
    
        Calendar cal = new GregorianCalendar();
        cal.setTime(date);
        cal.set(Calendar.DATE, cal.get(Calendar.DATE) + i);
        return cal.getTime();
    }


    /**
     * 返回某个日期前几天的日期
     */
    public static Date getFrontDay(Date date, int i) {
    
    
        Calendar cal = new GregorianCalendar();
        cal.setTime(date);
        cal.set(Calendar.DATE, cal.get(Calendar.DATE) - i);
        return cal.getTime();
    }


    /**
     * 获取某年某月按天切片日期集合（某个月间隔多少天的日期集合）
     */
    @SuppressWarnings({
    
    "unchecked", "rawtypes"})
    public static List getTimeList(int beginYear, int beginMonth, int k) {
    
    
        List list = new ArrayList();
        Calendar begincal = new GregorianCalendar(beginYear, beginMonth, 1);
        int max = begincal.getActualMaximum(Calendar.DATE);
        for (int i = 1; i < max; i = i + k) {
    
    
            list.add(begincal.getTime());
            begincal.add(Calendar.DATE, k);
        }
        begincal = new GregorianCalendar(beginYear, beginMonth, max);
        list.add(begincal.getTime());
        return list;
    }


    /**
     * 获取某年某月到某年某月按天的切片日期集合（间隔天数的集合）
     */
    @SuppressWarnings({
    
    "rawtypes", "unchecked"})
    public static List getTimeList(int beginYear, int beginMonth, int endYear, int endMonth, int k) {
    
    
        List list = new ArrayList();
        if (beginYear == endYear) {
    
    
            for (int j = beginMonth; j <= endMonth; j++) {
    
    
                list.add(getTimeList(beginYear, j, k));
            }
        } else {
    
    
            {
    
    
                for (int j = beginMonth; j < 12; j++) {
    
    
                    list.add(getTimeList(beginYear, j, k));
                }
                for (int i = beginYear + 1; i < endYear; i++) {
    
    
                    for (int j = 0; j < 12; j++) {
    
    
                        list.add(getTimeList(i, j, k));
                    }
                }
                for (int j = 0; j <= endMonth; j++) {
    
    
                    list.add(getTimeList(endYear, j, k));
                }
            }
        }
        return list;
    }


    //=================================时间格式转换==========================

    /**
     * date类型进行格式化输出（返回类型：String）
     */
    public static String dateFormat(Date date) {
    
    
        SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        String dateString = formatter.format(date);
        return dateString;
    }


    /**
     * 将"2015-08-31 21:08:06"型字符串转化为Date
     */
    public static Date StringToDate(String str) throws ParseException {
    
    
        SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        Date date = formatter.parse(str);
        return date;
    }


    /**
     * 将CST时间类型字符串进行格式化输出
     */
    public static String CSTFormat(String str) throws ParseException {
    
    
        SimpleDateFormat formatter = new SimpleDateFormat("EEE MMM dd HH:mm:ss zzz yyyy", Locale.US);
        Date date = formatter.parse(str);
        return dateFormat(date);
    }


    /**
     * 将long类型转化为Date
     */
    public static Date LongToDare(long str) throws ParseException {
    
    
        return new Date(str * 1000);
    }


    //====================================其他常见日期操作方法======================

    /**
     * 判断当前日期是否在[startDate, endDate]区间
     *
     * @param startDate 开始日期
     * @param endDate   结束日期
     */
    public static boolean isEffectiveDate(Date startDate, Date endDate) {
    
    
        if (startDate == null || endDate == null) {
    
    
            return false;
        }
        long currentTime = new Date().getTime();
        return currentTime >= startDate.getTime()
                && currentTime <= endDate.getTime();
    }


    /**
     * 得到二个日期间的间隔天数
     *
     * @param secondString：后一个日期
     * @param firstString：前一个日期
     */
    public static String getTwoDay(String secondString, String firstString) {
    
    
        SimpleDateFormat myFormatter = new SimpleDateFormat("yyyy-MM-dd");
        long day = 0;
        try {
    
    
            Date secondTime = myFormatter.parse(secondString);
            Date firstTime = myFormatter.parse(firstString);
            day = (secondTime.getTime() - firstTime.getTime()) / (24 * 60 * 60 * 1000);
        } catch (Exception e) {
    
    
            return "";
        }
        return day + "";
    }


    /**
     * 时间前推或后推分钟,其中JJ表示分钟.
     *
     * @param StringTime：时间
     * @param minute：分钟（有正负之分）
     */
    public static String getPreTime(String StringTime, String minute) {
    
    
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        String mydate1 = "";
        try {
    
    
            Date date1 = format.parse(StringTime);
            long Time = (date1.getTime() / 1000) + Integer.parseInt(minute) * 60;
            date1.setTime(Time * 1000);
            mydate1 = format.format(date1);
        } catch (Exception e) {
    
    
            return "";
        }
        return mydate1;
    }


    /**
     * 将短时间格式字符串转换为时间 yyyy-MM-dd
     */
    public static Date strToDate(String strDate) {
    
    
        SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd");
        ParsePosition pos = new ParsePosition(0);
        Date strtodate = formatter.parse(strDate, pos);
        return strtodate;
    }


    /**
     * 得到一个时间延后或前移几天的时间
     *
     * @param nowdate：时间
     * @param delay：前移或后延的天数
     */
    public static String getNextDay(String nowdate, String delay) {
    
    
        try {
    
    
            SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
            String mdate = "";
            Date d = strToDate(nowdate);
            long myTime = (d.getTime() / 1000) + Integer.parseInt(delay) * 24 * 60 * 60;
            d.setTime(myTime * 1000);
            mdate = format.format(d);
            return mdate;
        } catch (Exception e) {
    
    
            return "";
        }
    }


    /**
     * 判断是否闰年
     */
    public static boolean isLeapYear(String ddate) {
    
    
        /**
         * 详细设计： 1.被400整除是闰年，否则： 2.不能被4整除则不是闰年 3.能被4整除同时不能被100整除则是闰年
         * 3.能被4整除同时能被100整除则不是闰年
         */
        Date d = strToDate(ddate);
        GregorianCalendar gc = (GregorianCalendar) Calendar.getInstance();
        gc.setTime(d);
        int year = gc.get(Calendar.YEAR);
        if ((year % 400) == 0) {
    
    
            return true;
        } else if ((year % 4) == 0) {
    
    
            return (year % 100) != 0;
        } else {
    
    
            return false;
        }
    }


    /**
     * 返回美国时间格式
     */
    public static String getEDate(String str) {
    
    
        SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd");
        ParsePosition pos = new ParsePosition(0);
        Date strtodate = formatter.parse(str, pos);
        String j = strtodate.toString();
        String[] k = j.split(" ");
        return k[2] + k[1].toUpperCase() + k[5].substring(2, 4);
    }


    /**
     * 判断二个时间是否在同一个周
     */
    public static boolean isSameWeekDates(Date date1, Date date2) {
    
    
        Calendar cal1 = Calendar.getInstance();
        Calendar cal2 = Calendar.getInstance();
        cal1.setTime(date1);
        cal2.setTime(date2);
        int subYear = cal1.get(Calendar.YEAR) - cal2.get(Calendar.YEAR);
        if (0 == subYear) {
    
    
            return cal1.get(Calendar.WEEK_OF_YEAR) == cal2.get(Calendar.WEEK_OF_YEAR);
        } else if (1 == subYear && 11 == cal2.get(Calendar.MONTH)) {
    
    
            // 如果12月的最后一周横跨来年第一周的话则最后一周即算做来年的第一周
            return cal1.get(Calendar.WEEK_OF_YEAR) == cal2.get(Calendar.WEEK_OF_YEAR);
        } else if (-1 == subYear && 11 == cal1.get(Calendar.MONTH)) {
    
    
            return cal1.get(Calendar.WEEK_OF_YEAR) == cal2.get(Calendar.WEEK_OF_YEAR);
        }
        return false;
    }


    /**
     * 产生周序列,即得到当前时间所在的年度是第几周
     */
    public static String getSeqWeek() {
    
    
        Calendar c = Calendar.getInstance(Locale.CHINA);
        String week = Integer.toString(c.get(Calendar.WEEK_OF_YEAR));
        if (week.length() == 1)
            week = "0" + week;
        String year = Integer.toString(c.get(Calendar.YEAR));
        return year + "年第" + week + "周";
    }


    /**
     * 获得一个日期所在的周的星期几的日期，如要找出2002年2月3日所在周的星期一是几号
     *
     * @param sdate：日期
     * @param num：星期几（星期天是一周的第一天）
     */
    public static String getWeek(String sdate, String num) {
    
    
        // 再转换为时间
        Date dd = strToDate(sdate);
        Calendar c = Calendar.getInstance();
        c.setTime(dd);
        if (num.equals("1")) // 返回星期一所在的日期
            c.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
        else if (num.equals("2")) // 返回星期二所在的日期
            c.set(Calendar.DAY_OF_WEEK, Calendar.TUESDAY);
        else if (num.equals("3")) // 返回星期三所在的日期
            c.set(Calendar.DAY_OF_WEEK, Calendar.WEDNESDAY);
        else if (num.equals("4")) // 返回星期四所在的日期
            c.set(Calendar.DAY_OF_WEEK, Calendar.THURSDAY);
        else if (num.equals("5")) // 返回星期五所在的日期
            c.set(Calendar.DAY_OF_WEEK, Calendar.FRIDAY);
        else if (num.equals("6")) // 返回星期六所在的日期
            c.set(Calendar.DAY_OF_WEEK, Calendar.SATURDAY);
        else if (num.equals("0")) // 返回星期日所在的日期
            c.set(Calendar.DAY_OF_WEEK, Calendar.SUNDAY);
        return new SimpleDateFormat("yyyy-MM-dd").format(c.getTime());
    }


    /**
     * 根据一个日期，返回是星期几的字符串
     */
    public static String getWeek(String sdate) {
    
    
        // 再转换为时间
        Date date = strToDate(sdate);
        Calendar c = Calendar.getInstance();
        c.setTime(date);
        // int hour=c.get(Calendar.DAY_OF_WEEK);
        // hour中存的就是星期几了，其范围 1~7
        // 1=星期日 7=星期六，其他类推
        return new SimpleDateFormat("EEEE").format(c.getTime());
    }


    /**
     * 根据一个日期，返回是星期几的字符串
     */
    public static String getWeekStr(String sdate) {
    
    
        String str = "";
        str = getWeek(sdate);
        if ("1".equals(str)) {
    
    
            str = "星期日";
        } else if ("2".equals(str)) {
    
    
            str = "星期一";
        } else if ("3".equals(str)) {
    
    
            str = "星期二";
        } else if ("4".equals(str)) {
    
    
            str = "星期三";
        } else if ("5".equals(str)) {
    
    
            str = "星期四";
        } else if ("6".equals(str)) {
    
    
            str = "星期五";
        } else if ("7".equals(str)) {
    
    
            str = "星期六";
        }
        return str;
    }


    /**
     * 两个时间之间的天数
     */
    public static long getDays(String date1, String date2) {
    
    
        if (date1 == null || date1.equals(""))
            return 0;
        if (date2 == null || date2.equals(""))
            return 0;
        // 转换为标准时间
        SimpleDateFormat myFormatter = new SimpleDateFormat("yyyy-MM-dd");
        Date date = null;
        Date mydate = null;
        try {
    
    
            date = myFormatter.parse(date1);
            mydate = myFormatter.parse(date2);
        } catch (Exception e) {
    
    
        }
        long day = (date.getTime() - mydate.getTime()) / (24 * 60 * 60 * 1000);
        return day;
    }


    /**
     * 形成如下的日历 ， 根据传入的一个时间返回一个结构 星期日 星期一 星期二 星期三 星期四 星期五 星期六 下面是当月的各个时间
     * 此函数返回该日历第一行星期日所在的日期
     */
    public static String getNowMonth(String sdate) {
    
    
        // 取该时间所在月的一号
        sdate = sdate.substring(0, 8) + "01";

        // 得到这个月的1号是星期几
        Date date = strToDate(sdate);
        Calendar c = Calendar.getInstance();
        c.setTime(date);
        int u = c.get(Calendar.DAY_OF_WEEK);
        String newday = getNextDay(sdate, (1 - u) + "");
        return newday;
    }


    /**
     * 将Date类型转换为字符串类型
     */
    public static String dateToStr(Date date, SimpleDateFormat sdf) {
    
    
        return sdf.format(date);
    }

    /**
     * 将字符串日期转换为Date类型
     */
    public static Date strToDate(String date, SimpleDateFormat sdf) {
    
    
        try {
    
    
            return sdf.parse(date);
        } catch (ParseException e) {
    
    
            e.printStackTrace();
        }
        return new Date();
    }

    /**
     * 将字符串日期转换为Date类型
     */
    public static Date strToDate(String date, int length) {
    
    
        try {
    
    
            SimpleDateFormat sdf = FMT_LENGTH_MAP.get(length);
            if (null != sdf) {
    
    
                return sdf.parse(date);
            }
        } catch (ParseException e) {
    
    
            e.printStackTrace();
        }
        return new Date();
    }


    /**
     * 返回一个i位数的随机数
     */
    public static String getRandom(int i) {
    
    
        Random jjj = new Random();
        // int suiJiShu = jjj.nextInt(9);
        if (i == 0)
            return "";
        String jj = "";
        for (int k = 0; k < i; k++) {
    
    
            jj = jj + jjj.nextInt(9);
        }
        return jj;
    }


}
常用工具(十三) --DateUtil带详细注释

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