servlet - file upload problem... IndexOutOfBoundsException

Hi,

Im trying to allow a user to upload a file ( 0 - 1 meg). However when
the file gets larger than about 3k, its throwing an
IndexOutOfBoundsException.

Its odd that it works perfectly with extremely small files, yet breaks
on still very small files. What is the deal?

I gave the code below (mostly taken from sample code found on the web),
Im lost, please help! Im sure its something simple,,, simply
irritating!

Thank you so much in advance!

---------

    private void doStuff(PrintWriter out, String strContentType,
            ServletInputStream disRequest, int iContentLength){

        String strFileString = "";

        String contentType = strContentType;
        if ((contentType != null) &&
(contentType.indexOf("multipart/form-data") >= 0)) {
            DataInputStream in = new DataInputStream(disRequest);
            int formDataLength = iContentLength;

            byte dataBytes[] = new byte[formDataLength];
            int byteRead = 0;
            int totalBytesRead = 0;
            while (totalBytesRead < formDataLength) {
                try{
                    byteRead = in.read(dataBytes, totalBytesRead, formDataLength -
totalBytesRead);
                    totalBytesRead += byteRead;
                }catch(IOException ioe){
                    out.println("IOException: ERROR analyzing file. Error
Code:en3kd");
                }
            }

            String file = new String(dataBytes);
            strFileString = file.substring(file.indexOf("filename=\"") + 10);
            strFileString = strFileString.substring(0,
strFileString.indexOf("\n"));
            strFileString =
strFileString.substring(strFileString.lastIndexOf("\\") +
1,strFileString.indexOf("\""));

            int lastIndex = contentType.lastIndexOf("=");
            String boundary = contentType.substring(lastIndex +
1,contentType.length());

            int pos;
            pos = file.indexOf("filename=\"");
            pos = file.indexOf("\n", pos) + 1;
            pos = file.indexOf("\n", pos) + 1;
            pos = file.indexOf("\n", pos) + 1;

            int boundaryLocation = file.indexOf(boundary, pos) - 4;
            int startPos = ((file.substring(0, pos)).getBytes()).length;
            int endPos = ((file.substring(0,
boundaryLocation)).getBytes()).length;

            String strTheirFileName = strFileString;
            strFileString = "/tmp/" + strFileString;

            boolean bVtEnding = false;
            if (strFileString.endsWith("vt")){
                //good, continue
                bVtEnding = true;
            }else{
                //bad, exit
                out.println("You can only finalize unfinalized VideoTagger
files.");
                out.flush();
            }

            if (bVtEnding){
                File filOld = null;
                try{
                    filOld = new File(strFileString);
                    filOld.createNewFile();
                    FileOutputStream fos = new FileOutputStream(filOld);
                    //breaks on this line. :(
                    fos.write(dataBytes, startPos, (endPos - startPos));
                    fos.flush();
                    fos.close();
                }catch(FileNotFoundException fnfe){
                    out.println("FileNotFoundException: <b>Error</b>, could not find
upload file... Error Code:md9ww");
                    out.println("<b>ERROR</b>");
                }catch(IOException ioe){
                    out.println("IOException: ERROR analyzing file... <b>Error</b>
Code:pl1nm " + strFileString + "<br><br>" +
ioe.getLocalizedMessage());
                    out.println("<b>ERROR</b>");
                }//catch(IndexOutOfBoundsException iobe){
                // out.println("IndexOutOfBoundsException: <b>ERROR</b> analyzing
file... Error Code:ne8ni<br>");
                // out.println("<b>ERROR</b>");
                // iobe.printStackTrace();
                //}
}
}