Basic File Upload in GWT

Client: 

public class FileUploader{

    private ControlPanel cp;
    private FormPanel form = new FormPanel();
    private FileUpload fu =  new FileUpload();

    public FileUploader(ControlPanel cp) {
     this.cp = cp;
     this.cp.setPrimaryArea(getFileUploaderWidget());
    }

    @SuppressWarnings("deprecation")
    public Widget getFileUploaderWidget() {
     form.setEncoding(FormPanel.ENCODING_MULTIPART);
     form.setMethod(FormPanel.METHOD_POST);
     // form.setAction(/* WHAT SHOULD I PUT HERE */);

     VerticalPanel holder = new VerticalPanel();

     fu.setName("upload");
     holder.add(fu);
     holder.add(new Button("Submit", new ClickHandler() {
      public void onClick(ClickEvent event) {
       GWT.log("You selected: " + fu.getFilename(), null);
       form.submit();
      }
     }));

     form.addSubmitHandler(new FormPanel.SubmitHandler() {
      public void onSubmit(SubmitEvent event) {
       if (!"".equalsIgnoreCase(fu.getFilename())) {
        GWT.log("UPLOADING FILE????", null);
                                        // NOW WHAT????
       }
       else{
        event.cancel(); // cancel the event
       }

      }
     });

     form.addSubmitCompleteHandler(new FormPanel.SubmitCompleteHandler() {
      public void onSubmitComplete(SubmitCompleteEvent event) {
       Window.alert(event.getResults());
      }
     });

     form.add(holder);

     return form;
    }
}

Server:

import java.io.IOException;
import java.io.InputStream;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet; 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 
import org.apache.commons.fileupload.FileItemIterator; 
import org.apache.commons.fileupload.FileItemStream; 
import org.apache.commons.fileupload.servlet.ServletFileUpload; 

public class FileUpload extends HttpServlet{
    public void doPost(HttpServletRequest request, HttpServletResponse response)  throws ServletException, IOException {
        ServletFileUpload upload = new ServletFileUpload();

        try{
            FileItemIterator iter = upload.getItemIterator(request);

            while (iter.hasNext()) {
                FileItemStream item = iter.next();

                String name = item.getFieldName();
                InputStream stream = item.openStream();


                // Process the input stream
                ByteArrayOutputStream out = new ByteArrayOutputStream();
                int len;
                byte[] buffer = new byte[8192];
                while ((len = stream.read(buffer, 0, buffer.length)) != -1) {
                    out.write(buffer, 0, len);
                }

                int maxFileSize = 10*(1024*1024); //10 megs max 
                if (out.size() > maxFileSize) { 
                    throw new RuntimeException("File is > than " + maxFileSize);
                }
            }
        }
        catch(Exception e){
            throw new RuntimeException(e);
        }

    }
} 

web.xml

<servlet>
    <servlet-name>fileUploaderServlet</servlet-name>
    <servlet-class>com.testapp.server.FileUpload</servlet-class>
</servlet>
<servlet-mapping>
  <servlet-name>fileUploaderServlet</servlet-name>
  <url-pattern>/testapp/fileupload</url-pattern>
</servlet-mapping>

And: 

form.setAction(GWT.getModuleBaseURL()+"fileupload");