Upload image to server in GWT project using Servlet - gwt

Question

I am developing a GWT application which, among its other functions, permits the user to upload an image file and to store it on the server.
So far, that's what I've done..
SERVLET
public class ImageUploadService extends HttpServlet {
private static final int MAX_FILE_SIZE = 1 * 1024 * 1024;
public void doPost(HttpServletRequest request, HttpServletResponse response) {
wlog("INFO: è partita la servlet");
if (!ServletFileUpload.isMultipartContent(request))
wlog("ERR: non è multipart!");
ServletFileUpload fileUpld = new ServletFileUpload();
try {
wlog("INFO: itero file");
FileItemIterator fileIt = fileUpld.getItemIterator(request);
while (fileIt.hasNext()) {
wlog("INFO: trovato file");
FileItemStream fileStream = fileIt.next();
BufferedInputStream in = new BufferedInputStream(
fileStream.openStream(), 4096);
BufferedOutputStream out = new BufferedOutputStream(
new FileOutputStream("immagineSegnalazione.jpg"));
byte[] buf = new byte[MAX_FILE_SIZE];
int byteRead;
while ((byteRead = in.read(buf, 0, MAX_FILE_SIZE)) >= 0) {
out.write(buf, 0, byteRead);
}
in.close();
out.flush();
out.close();
}
} catch (Exception e) {
e.printStackTrace();
}
}
private void wlog(String s) {
System.out.println("UPLOAD SERVLET " + s);
}
}
MODULE ON CLIENT SIDE
[...]
PopupPanel inserisciSegnalazionePopup = new PopupPanel();
final FormPanel uploadForm = new FormPanel();
uploadForm.setEncoding(FormPanel.ENCODING_MULTIPART);
uploadForm.setMethod(FormPanel.METHOD_POST);
inserisciSegnalazionePopup.setAutoHideEnabled(true);
VerticalPanel holder = new VerticalPanel();
holder.add(new Label("se puoi, allega una foto della segnalazione"));
final FileUpload fu = new FileUpload();
uploadForm.add(fu);
holder.add(uploadForm);
uploadForm.setAction(GWT.getModuleBaseURL() + "imageUpload");
Button inviaBtn = new Button("INVIA SEGNALAZIONE");
inviaBtn.addClickHandler(new ClickHandler() {
#Override
public void onClick(ClickEvent event) {
// TODO check file is image and size and other stuff
uploadForm.submit();
}
});
holder.add(inviaBtn);
[...]
..plus I've rightly made the changes needed on web.xml
The Servlet is correctly called and the method doPost() starts, but the FileItemIterator is always empty, as if there were no files at all..
Can someone guess what's wrong? I can't really see where's the mistake
Thank you in advance

Answer 1

just guessing I would say the request is parsed somewhere befor you use it. Try taking a look at that question and the answer to it, it seems to like it was nearly the same problem.
Sarajog

Answer 2

Have you tried this ??
Iterator<FileItem> iterator = upload.parseRequest(request).iterator();

Answer 3

The solution is...
Simply add .setName() to the FileUpload widget