How do I validate a timestamp?

问题:

my application takes in a string like this "2002-10-15 10:55:01.000000". I need to validate that the string is a valid for a db2 timestamp.

How can I do this?

EDIT: This mostly works

     public static boolean isTimeStampValid(String inputString) {
     SimpleDateFormat format = new java.text.SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSSSSS");
        try {
            format.parse(inputString);
            return true;
        } catch (ParseException e) {
            return false;
        }
     }

The problem is that if I pass it a bad format for milliseconds like "2011-05-02 10:10:01.0av" this will pass validation. I am assuming that since the first millisecond character is valid then it just truncates the rest of the string.

回答1:

I'm not exactly sure about the format but you you can play around it and can try something like this

public static bool isTimeStampValid(String inputString)
{ 
    SimpleDateFormat format = new java.text.SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSSSSS");
    try{
       format.parse(inputString);
       return true;
    }
    catch(ParseException e)
    {
        return false;
    }
}

EDIT: if you want to validate for numbers after successful parsing, you could do

       format.parse(inputString);
       Pattern p = Pattern.compile("^\\d{4}[-]?\\d{1,2}[-]?\\d{1,2} \\d{1,2}:\\d{1,2}:\\d{1,2}[.]?\\d{1,6}$");
       return p.matcher(inputString).matches();

instead of

   format.parse(inputString);
   return true;

回答2:

http://download.oracle.com/javase/6/docs/api/java/text/SimpleDateFormat.html

I believe the format would be "yyyy-MM-dd HH:mm:ss.SSSSSS"

Call parse(String) and catch ParseException indicating it is invalid.

回答3:

/**
 * This method validates the given time stamp in String format
 * @param timestamp
 * @return
 */

public static boolean isTimeStampValid(String timestamp) {
    //(Considering that formal will be yyyy-MM-dd HH:mm:ss.SSSSSS )
    //Tokenize string and separate date and time
    boolean time = false;
    try {
            //Tokenize string and separate date and time
            StringTokenizer st = new StringTokenizer(timestamp, " ");

            if (st.countTokens() != 2) {
                return false;
            }

            String[] dateAndTime = new String[2];

            int i = 0;
            while (st.hasMoreTokens()) {
                dateAndTime[i] = st.nextToken();
                i++;
            }

            String timeToken = dateAndTime[1];

            StringTokenizer timeTokens = new StringTokenizer(timeToken, ":");
            if (timeTokens.countTokens() != 3) {
                return false;
            }

            String[] timeAt = new String[4];
            int j = 0;
            while (timeTokens.hasMoreTokens()) {
                timeAt[j] = timeTokens.nextToken();
                j++;
            }
            try {
                    int HH = Integer.valueOf(timeAt[0].toString());
                    int mm = Integer.valueOf(timeAt[1].toString());
                    float ss = Float.valueOf(timeAt[2].toString());


                    if (HH < 60 && HH >= 0 && mm < 60 && mm >= 0 && ss < 60 && ss >= 0) {
                        time = true;
                    } else {
                    }
            } catch (Exception e) {
                e.printStackTrace();
            }
            //Got Date
            String dateToken = dateAndTime[0];//st.nextToken();

            //Tokenize separated date and separate year-month-day
            StringTokenizer dateTokens = new StringTokenizer(dateToken, "-");
            if (dateTokens.countTokens() != 3) {
                return false;
            }
            String[] tokenAt = new String[3];

            //This will give token string array with year month and day value.
            int k = 0;
            while (dateTokens.hasMoreTokens()) {
                tokenAt[k] = dateTokens.nextToken();
                k++;
            }

            //Now try to create new date with got value of date
            int dayInt = Integer.parseInt(tokenAt[2]);
            int monthInt = Integer.parseInt(tokenAt[1]);
            int yearInt = Integer.parseInt(tokenAt[0]);
            Calendar cal = new GregorianCalendar();
            cal.setLenient(false);
            cal.set(yearInt, monthInt - 1, dayInt);
            cal.getTime();//If not able to create date it will throw error



    } catch (Exception e) {
        e.printStackTrace();
        return false;
    }
    //Here we ll check for correct format is provided else it ll return false
    try {
            Pattern p = Pattern.compile("^\\d{4}[-]?\\d{1,2}[-]?\\d{1,2} \\d{1,2}:\\d{1,2}:\\d{1,2}[.]?\\d{1,6}$");
            if (p.matcher(timestamp).matches()) {
            } else {
                return false;
            }

    } catch (Exception e) {
        e.printStackTrace();
        return false;
    }
    //Cross checking with simple date format to get correct time stamp only
    SimpleDateFormat format = new java.text.SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSSSSS");
    try {
            format.parse(timestamp);
            //return true;

            if (time) {
                return true;
            } else {
                return false;
            }
    } catch (ParseException e) {
        e.printStackTrace();
        return false;
    } catch (Exception e) {
        e.printStackTrace();
        return false;
    }

}

回答4:

If you're already connected to the database, you can execute a query that attempts to cast the input string as a timestamp, and check for a failure message (in this case, SQLSTATE 22007).

VALUES CAST( ? AS TIMESTAMP )

The above query will fully validate the input string while consuming hardly any resources on the database server. If the string is invalid for any reason, your database client will encounter an exception.