Rename file extension during a file upload ??

Question

I need to rename the extension of a file at some point during the file upload. I am not sure where to do this at.
The file needs to be renamed before it is written to the directory.
Basically, the file will come in with a .txt or .doc type. Based on a users profile, I will change the type to a non-relavent number such as 1111.
Here is my upload servlet. Can you tell me where to change the type so it will write the file with the new extension?
Thanks.
public class FileExport {
//restrict upload files to 1 Meg
private static final int DEFAULT_MAX_POST_SIZE = 1024 * 1024;
private static final String NO_FILE = "unknown";
private HttpServletRequest req;
private File dir;
private int maxSize;
private Hashtable parameters = new Hashtable(); // name - Vector of values
private Hashtable files = new Hashtable(); // name - UploadedFile
public FileExport(HttpServletRequest request,
String saveDirectory) throws IOException {
this(request, saveDirectory, DEFAULT_MAX_POST_SIZE);
// request the servlet request
// saveDirectory = directory in which to save any uploaded files
// maxPostSize = maximum size of the POST content
public FileExport(HttpServletRequest request,
String saveDirectory,
int maxPostSize) throws IOException {
// check values
if (request == null)
throw new IllegalArgumentException("request cannot be null");
if (saveDirectory == null)
throw new IllegalArgumentException("saveDirectory cannot be null");
if (maxPostSize <= 0) {
throw new IllegalArgumentException("maxPostSize must be positive");
// Save the request, dir, and max size
req = request;
dir = new File(saveDirectory);
maxSize = maxPostSize;
// Check saveDirectory is truly a directory
if (!dir.isDirectory())
throw new IllegalArgumentException("Not a directory: " + saveDirectory);
// Check saveDirectory is writable
if (!dir.canWrite())
throw new IllegalArgumentException("Not writable: " + saveDirectory);
// Now parse the request saving data to "parameters" and "files";
// write the file contents to the saveDirectory
readRequest();
public FileExport(ServletRequest request,
String saveDirectory) throws IOException {
this((HttpServletRequest)request, saveDirectory);
public FileExport(ServletRequest request,
String saveDirectory,
int maxPostSize) throws IOException {
this((HttpServletRequest)request, saveDirectory, maxPostSize);
// Returns the names of all the parameters as an Enumeration of
// Strings. It returns an empty Enumeration if there are no parameters.
public Enumeration getParameterNames() {
return parameters.keys();
// Returns the names of all the uploaded files as an Enumeration of
// Strings. It returns an empty Enumeration if there are no uploaded
// files. Each file name is the name specified by the form, not by
// the user.
public Enumeration getFileNames() {
return files.keys();
// Returns the value of the named parameter as a String, or null if
// the parameter was not sent or was sent without a value.
public String getParameter(String name) {
try {
Vector values = (Vector)parameters.get(name);
if (values == null || values.size() == 0) {
return null;
String value = (String)values.elementAt(values.size() - 1);
return value;
catch (Exception e) {
return null;
// Returns the values of the named parameter as a String array, or null if
// the parameter was not sent.
public String[] getParameterValues(String name) {
try {
Vector values = (Vector)parameters.get(name);
if (values == null || values.size() == 0) {
return null;
String[] valuesArray = new String[values.size()];
values.copyInto(valuesArray);
return valuesArray;
catch (Exception e) {
return null;
// Returns the filesystem name of the specified file, or null if the
// file was not included in the upload. A filesystem name is the name
// specified by the user. It is also the name under which the file is
// actually saved.
public String getFilesystemName(String name) {
try {
UploadedFile file = (UploadedFile)files.get(name);
return file.getFilesystemName(); // may be null
catch (Exception e) {
return null;
// Returns the content type of the specified file (as supplied by the
//client browser), or null if the file was not included in the upload.
public String getContentType(String name) {
try {
UploadedFile file = (UploadedFile)files.get(name);
return file.getContentType(); // may be null
catch (Exception e) {
return null;
// Returns a File object for the specified file saved on the server's
// filesystem, or null if the file was not included in the upload.
public File getFile(String name) {
try {
UploadedFile file = (UploadedFile)files.get(name);
return file.getFile(); // may be null
catch (Exception e) {
return null;
// method that actually parses the request.
protected void readRequest() throws IOException {
// Check the content length to prevent denial of service attacks
int length = req.getContentLength();
if (length > maxSize) {
throw new IOException("Posted content length of " + length +
" exceeds limit of " + maxSize);
// Check the content type to make sure it's "multipart/form-data"
// Access header two ways to work around WebSphere oddities
String type = null;
String type1 = req.getHeader("Content-Type");
String type2 = req.getContentType();
// If one value is null, choose the other value
if (type1 == null && type2 != null) {
type = type2;
else if (type2 == null && type1 != null) {
type = type1;
// If neither value is null, choose the longer value
else if (type1 != null && type2 != null) {
type = (type1.length() > type2.length() ? type1 : type2);
if (type == null ||
!type.toLowerCase().startsWith("multipart/form-data")) {
throw new IOException("Posted content type isn't multipart/form-data");
// Get the boundary string; it's included in the content type.
// Should look something like "------------------------12012133613061"
String boundary = extractBoundary(type);
if (boundary == null) {
throw new IOException("Separation boundary was not specified");
// Construct the special input stream we'll read from
MultipartInputStreamHandler in =
new MultipartInputStreamHandler(req.getInputStream(), length);
// Read the first line, should be the first boundary
String line = in.readLine();
if (line == null) {
throw new IOException("Corrupt form data: premature ending");
// Verify that the line is the boundary
if (!line.startsWith(boundary)) {
throw new IOException("Corrupt form data: no leading boundary");
// Now that we're just beyond the first boundary, loop over each part
boolean done = false;
while (!done) {
done = readNextPart(in, boundary);
// A utility method that reads an individual part. Dispatches to
// readParameter() and readAndSaveFile() to do the actual work. A
// subclass can override this method for a better optimized or
// differently behaved implementation.
protected boolean readNextPart(MultipartInputStreamHandler in,
String boundary) throws IOException {
// Read the first line, should look like this:
// content-disposition: form-data; name="field1"; filename="file1.txt"
String line = in.readLine();
if (line == null) {
// No parts left, we're done
return true;
else if (line.length() == 0) {
// IE4 on Mac sends an empty line at the end; treat that as the end.
// Thanks to Daniel Lemire and Henri Tourigny for this fix.
return true;
// Parse the content-disposition line
String[] dispInfo = extractDispositionInfo(line);
String disposition = dispInfo[0];
String name = dispInfo[1];
String filename = dispInfo[2];
// Now onto the next line. This will either be empty
// or contain a Content-Type and then an empty line.
line = in.readLine();
if (line == null) {
// No parts left, we're done
return true;
// Get the content type, or null if none specified
String contentType = extractContentType(line);
if (contentType != null) {
// Eat the empty line
line = in.readLine();
if (line == null || line.length() > 0) {  // line should be empty
throw new
IOException("Malformed line after content type: " + line);
else {
// Assume a default content type
contentType = "application/octet-stream";
// Now, finally, we read the content (end after reading the boundary)
if (filename == null) {
// This is a parameter, add it to the vector of values
String value = readParameter(in, boundary);
if (value.equals("")) {
value = null; // treat empty strings like nulls
Vector existingValues = (Vector)parameters.get(name);
if (existingValues == null) {
existingValues = new Vector();
parameters.put(name, existingValues);
existingValues.addElement(value);
else {
// This is a file
readAndSaveFile(in, boundary, filename, contentType);
if (filename.equals(NO_FILE)) {
files.put(name, new UploadedFile(null, null, null));
else {
files.put(name,
new UploadedFile(dir.toString(), filename, contentType));
return false; // there's more to read
// A utility method that reads a single part of the multipart request
// that represents a parameter. A subclass can override this method
// for a better optimized or differently behaved implementation.
protected String readParameter(MultipartInputStreamHandler in,
String boundary) throws IOException {
StringBuffer sbuf = new StringBuffer();
String line;
while ((line = in.readLine()) != null) {
if (line.startsWith(boundary)) break;
sbuf.append(line + "\r\n"); // add the \r\n in case there are many lines
if (sbuf.length() == 0) {
return null; // nothing read
sbuf.setLength(sbuf.length() - 2); // cut off the last line's \r\n
return sbuf.toString(); // no URL decoding needed
// A utility method that reads a single part of the multipart request
// that represents a file, and saves the file to the given directory.
// A subclass can override this method for a better optimized or
// differently behaved implementation.
protected void readAndSaveFile(MultipartInputStreamHandler in,
String boundary,
String filename,
String contentType) throws IOException {
OutputStream out = null;
// A filename of NO_FILE means no file was sent, so just read to the
// next boundary and ignore the empty contents
if (filename.equals(NO_FILE)) {
out = new ByteArrayOutputStream(); // write to nowhere
// A MacBinary file goes through a decoder
else if (contentType.equals("application/x-macbinary")){
File f = new File(dir + File.separator + filename);
out = new MacBinaryDecoderOutputStream(
new BufferedOutputStream(
new FileOutputStream(f), 8 * 1024));
// A real file's contents are written to disk
else {
File f = new File(dir + File.separator + filename);
out = new BufferedOutputStream(new FileOutputStream(f), 8 * 1024);
byte[] bbuf = new byte[100 * 1024]; // 100K
int result;
String line;
// ServletInputStream.readLine()
// adds a \r\n to the end of the last line.
// Since we want a byte-for-byte transfer, we have to cut those chars.
boolean rnflag = false;
while ((result = in.readLine(bbuf, 0, bbuf.length)) != -1) {
// Check for boundary
if (result > 2 && bbuf[0] == '-' && bbuf[1] == '-') { // quick pre-check
line = new String(bbuf, 0, result, "ISO-8859-1");
if (line.startsWith(boundary)) break;
// Are we supposed to write \r\n for the last iteration?
if (rnflag) {
out.write('\r'); out.write('\n');
rnflag = false;
// Write the buffer, postpone any ending \r\n
if (result >= 2 &&
bbuf[result - 2] == '\r' &&
bbuf[result - 1] == '\n') {
out.write(bbuf, 0, result - 2); // skip the last 2 chars
rnflag = true; // make a note to write them on the next iteration
else {
out.write(bbuf, 0, result);
out.flush();
out.close();
// Extracts and returns the boundary token from a line.
private String extractBoundary(String line) {
// Use lastIndexOf() because IE 4.01 on Win98 has been known to send the
// "boundary=" string multiple times. Thanks to David Wall for this fix.
int index = line.lastIndexOf("boundary=");
if (index == -1) {
return null;
String boundary = line.substring(index + 9); // 9 for "boundary="
// The real boundary is always preceeded by an extra "--"
boundary = "--" + boundary;
return boundary;
// Extracts and returns disposition info from a line, as a String array
// with elements: disposition, name, filename. Throws an IOException
// if the line is malformatted.
private String[] extractDispositionInfo(String line) throws IOException {
// Return the line's data as an array: disposition, name, filename
String[] retval = new String[3];
// Convert the line to a lowercase string without the ending \r\n
// Keep the original line for error messages and for variable names.
String origline = line;
line = origline.toLowerCase();
// Get the content disposition, should be "form-data"
int start = line.indexOf("content-disposition: ");
int end = line.indexOf(";");
if (start == -1 || end == -1) {
throw new IOException("Content disposition corrupt: " + origline);
String disposition = line.substring(start + 21, end);
if (!disposition.equals("form-data")) {
throw new IOException("Invalid content disposition: " + disposition);
// Get the field name
start = line.indexOf("name=\"", end); // start at last semicolon
end = line.indexOf("\"", start + 7); // skip name=\"
if (start == -1 || end == -1) {
throw new IOException("Content disposition corrupt: " + origline);
String name = origline.substring(start + 6, end);
// Get the filename, if given
String filename = null;
start = line.indexOf("filename=\"", end + 2); // start after name
end = line.indexOf("\"", start + 10); // skip filename=\"
if (start != -1 && end != -1) {                // note the !=
filename = origline.substring(start + 10, end);
// The filename may contain a full path. Cut to just the filename.
int slash =
Math.max(filename.lastIndexOf('/'), filename.lastIndexOf('\\'));
if (slash > -1) {
filename = filename.substring(slash + 1); // past last slash
if (filename.equals("")) filename = NO_FILE; // sanity check
// Return a String array: disposition, name, filename
retval[0] = disposition;
retval[1] = name;
retval[2] = filename;
return retval;
// Extracts and returns the content type from a line, or null if the
// line was empty. Throws an IOException if the line is malformatted.
private String extractContentType(String line) throws IOException {
String contentType = null;
// Convert the line to a lowercase string
String origline = line;
line = origline.toLowerCase();
// Get the content type, if any
if (line.startsWith("content-type")) {
int start = line.indexOf(" ");
if (start == -1) {
throw new IOException("Content type corrupt: " + origline);
contentType = line.substring(start + 1);
else if (line.length() != 0) {  // no content type, so should be empty
throw new IOException("Malformed line after disposition: " + origline);
return contentType;
// A class to hold information about an uploaded file.
class UploadedFile {
private String dir;
private String filename;
private String type;
UploadedFile(String dir, String filename, String type) {
this.dir = dir;
this.filename = filename;
this.type = type;
public String getContentType() {
return type;
public String getFilesystemName() {
return filename;
public File getFile() {
if (dir == null || filename == null) {
return null;
else {
return new File(dir + File.separator + filename);
// A class to aid in reading multipart/form-data from a ServletInputStream.
// It keeps track of how many bytes have been read and detects when the
// Content-Length limit has been reached.
class MultipartInputStreamHandler {
ServletInputStream in;
int totalExpected;
int totalRead = 0;
byte[] buf = new byte[8 * 1024];
public MultipartInputStreamHandler(ServletInputStream in,
int totalExpected) {
this.in = in;
this.totalExpected = totalExpected;
// Reads the next line of input. Returns null to indicate the end
// of stream.
public String readLine() throws IOException {
StringBuffer sbuf = new StringBuffer();
int result;
String line;
do {
result = this.readLine(buf, 0, buf.length); // this.readLine() does +=
if (result != -1) {
sbuf.append(new String(buf, 0, result, "ISO-8859-1"));
} while (result == buf.length); // loop only if the buffer was filled
if (sbuf.length() == 0) {
return null; // nothing read, must be at the end of stream
sbuf.setLength(sbuf.length() - 2); // cut off the trailing \r\n
return sbuf.toString();
// A pass-through to ServletInputStream.readLine() that keeps track
// of how many bytes have been read and stops reading when the
// Content-Length limit has been reached.
public int readLine(byte b[], int off, int len) throws IOException {
if (totalRead >= totalExpected) {
return -1;
else {
if (len > (totalExpected - totalRead)) {
len = totalExpected - totalRead; // keep from reading off end
int result = in.readLine(b, off, len);
if (result > 0) {
totalRead += result;
return result;
// Class to filters MacBinary files to normal files on the fly
// Optimized for speed more than readability
class MacBinaryDecoderOutputStream extends FilterOutputStream {
int bytesFiltered = 0;
int dataForkLength = 0;
public MacBinaryDecoderOutputStream(OutputStream out) {
super(out);
public void write(int b) throws IOException {
// Bytes 83 through 86 are a long representing the data fork length
// Check <= 86 first to short circuit early in the common case
if (bytesFiltered <= 86 && bytesFiltered >= 83) {
int leftShift = (86 - bytesFiltered) * 8;
dataForkLength = dataForkLength | (b & 0xff) << leftShift;
// Bytes 128 up to (128 + dataForkLength - 1) are the data fork
else if (bytesFiltered < (128 + dataForkLength) && bytesFiltered >= 128) {
out.write(b);
bytesFiltered++;
public void write(byte b[]) throws IOException {
write(b, 0, b.length);
public void write(byte b[], int off, int len) throws IOException {
// If the write is for content past the end of the data fork, ignore
if (bytesFiltered >= (128 + dataForkLength)) {
bytesFiltered += len;
// If the write is entirely within the data fork, write it directly
else if (bytesFiltered >= 128 &&
(bytesFiltered + len) <= (128 + dataForkLength)) {
out.write(b, off, len);
bytesFiltered += len;
// Otherwise, do the write a byte at a time to get the logic above
else {
for (int i = 0 ; i < len ; i++) {
write(b[off + i]);

Answer 1

I am also need to rename a file and extension while uploadinf the file to the server. The oreilly example seems only save as the same file name and ext. I wonder if you have the ability chANGE OIT OR NOT. pLEASE LET ME KNOW
thanks
kansen