format abnormal date into normal date

/**
 * The newly added formatted time class, which standardizes the time format, is suitable for formatting the date passed in from the foreground into an actual and feasible date
 * For example, format 20050600 to 20050601, or format 20050631 to 20050630
 * @param _dateTime The original time string passed in
 * @param _format format character, YYYYMMDDHH24MISS, YYYYMMDDHH12MISS
 * @return String
 * @throws Exception
 */
public static String formatDateTime(String _dateTime, String _format) throws Exception
{
    String returnValue = "";
    String formatString = _format.toUpperCase();
    String strYear = "";
    String strMonth = "";
    String strDay = "";
    String strHour = "";
    String strMinu = "";
    String strSec = "";
    int hourType = 12; //12-hour format, 24-hour format
    int yearType = 1; //1 is normal year, 2 is leap year
    try
    {
        if (formatString.indexOf("YYYY") >= 0)
        {
            int tempBeginPlace = formatString.indexOf("YYYY");
            int tempEndPlace = tempBeginPlace + 4;
            strYear = _dateTime.substring(tempBeginPlace, temEndPlace);
        }
        if (formatString.indexOf("MM") >= 0)
        {
            int tempBeginPlace = formatString.indexOf("MM");
            int tempEndPlace = tempBeginPlace + 2;
            strMonth = _dateTime.substring(tempBeginPlace, temEndPlace);
        }
        if (formatString.indexOf("DD") >= 0)
        {
            int tempBeginPlace = formatString.indexOf("DD");
            int tempEndPlace = tempBeginPlace + 2;
            strDay = _dateTime.substring(tempBeginPlace, temEndPlace);
        }
        if (formatString.indexOf("HH24") >= 0)
        {
            int tempBeginPlace = formatString.indexOf("HH24");
            int tempEndPlace = tempBeginPlace + 2;
            strHour = _dateTime.substring(tempBeginPlace, temEndPlace);
            formatString = formatString.replaceAll("24", "");
            //In order to keep the number of digits consistent, remove 24
            hourType = 24;
        }
        else if (formatString.indexOf("HH12") >= 0)
        {
            int tempBeginPlace = formatString.indexOf("HH12");
            int tempEndPlace = tempBeginPlace + 2;
            strHour = _dateTime.substring(tempBeginPlace, temEndPlace);
            formatString = formatString.replaceAll("12", "");
            //In order to keep the number of digits consistent, remove 12
            hourType = 12;
        }
        else if (formatString.indexOf("HH") >= 0)
        {
            int tempBeginPlace = formatString.indexOf("HH");
            int tempEndPlace = tempBeginPlace + 2;
            strHour = _dateTime.substring(tempBeginPlace, temEndPlace);
            hourType = 12; //If the hour is not specified, the default is 12 hours;
        }
        if (formatString.indexOf("MI") >= 0)
        {
            int tempBeginPlace = formatString.indexOf("MI");
            int tempEndPlace = tempBeginPlace + 2;
            strMinu = _dateTime.substring(tempBeginPlace, tempEndPlace);
        }
        if (formatString.indexOf("SS") >= 0)
        {
            int tempBeginPlace = formatString.indexOf("SS");
            int tempEndPlace = tempBeginPlace + 2;
            strSec = _dateTime.substring(tempBeginPlace, temEndPlace);
        }

        // Check if it is a leap year
        if (!strYear.equals(""))
        {
            int intYear = Integer.parseInt(strYear);
            // Divisible by 4, but not divisible by 100 ② Divisible by 4, and divisible by 400
            if (intYear % 4 == 0)
            {
                if (intYear % 100 != 0)
                {
                    yearType = 2;
                }
            }
            if (intYear % 4 == 0)
            {
                if (intYear % 400 == 0)
                {
                    yearType = 2;
                }
            }
        }
        // format the month
        if (!strMonth.equals(""))
        {
            int intMonth = Integer.parseInt(strMonth);
            if (intMonth == 0)
            {
                strMonth = "01";
                intMonth = 1;
            }
            if (intMonth > 12)
            {
                strMonth = "12";
                intMonth = 12;
            }
        }

        // format date
        if (!strDay.equals(""))
        {
            int intDay = Integer.parseInt(strDay);
            if (intDay == 0)
            {
                strDay = "01";
                intDay = 1;
            }
            if (intDay > 31)
            {
                strDay = "31";
                intDay = 31;
            }
            if ((strMonth.equals("01"))
                    || (strMonth.equals("03"))
                    || (strMonth.equals("05"))
                    || (strMonth.equals("07"))
                    || (strMonth.equals("08"))
                    || (strMonth.equals("10"))
                    || (strMonth.equals("12")))
            {
                if (intDay > 31)
                {
                    strDay = "31";
                    intDay = 31;
                }
            }
            if ((strMonth.equals("02"))
                    || (strMonth.equals("04"))
                    || (strMonth.equals("06"))
                    || (strMonth.equals("09"))
                    || (strMonth.equals("11")))
            {
                if (intDay > 30)
                {
                    strDay = "30";
                    intDay = 30;
                }
                if (strMonth.equals("02"))
                { // Special treatment for February
                    if (yearType == 2)
                    {
                        if (intDay > 29)
                        {
                            strDay = "29";
                            intDay = 29;
                        }
                    }
                    else
                    {
                        if (intDay > 28)
                        {
                            strDay = "28";
                            intDay = 28;
                        }
                    }
                }
            }

            // format the hour
            if (!strHour.equals(""))
            {
                int intHour = Integer.parseInt(strHour);
                if (intHour > 24)
                {
                    strHour = "24";
                    intHour = 24;
                }
                if (hourType == 12)
                {
                    if (intHour == 0)
                    {
                        intHour = 1;
                        strHour = "01";
                    }
                    if (intHour > 12)
                    {
                        intHour = intHour - 12;
                        strHour = "0" + intHour;
                    }
                }
                else
                {
                    if (intHour > 23)
                    {
                        intHour = 23;
                        strHour = "23";
                    }
                }
            }
            // format points
            if (!strMinu.equals(""))
            {
                int intMinute = Integer.parseInt(strMinute);
                if (intMinu > 59)
                {
                    strMinu = "59";
                    intMin = 59;
                }
            }
            // format seconds
            if (!strSec.equals(""))
            {
                int intSec = Integer.parseInt(strSec);
                if (intSec > 59)
                {
                    strSec = "59";
                    intSec = 59;
                }
            }
        }
        returnValue = strYear + strMonth + strDay + strHour + strMinu + strSec;
        return returnValue;
    }
    catch (Exception e)
    {
        throw e;
    }
}