Create Image from Stream in Applet via Servlet

Question

First of all, I apologize if this isn't posted to the proper forum, as I am dealing with several topics here. I think this is more of an Image and I/O problem than Applet/Servlet problem, so I thought this forum would be most appropriate. It's funny...I've been developing Java for over 4 years and this is my first post to the forums! :D
The problem is I need to retrieve a map image (JPEG, GIF, etc) from an Open GIS Consortium (OGC) Web Map Server (WMS) and display that image in an OpenMap Applet as a layer. Due to the security constraints on Applets (e.g., can't connect to a server other than that from which it originated), I obviously just can't have the Applet create an ImageIcon from a URL. The OpenMap applet will need to connect to many remote WMS compliant servers.
The first solution I devised is for the applet to pass the String URL to a servlet as a parameter, the servlet will then instantiate the URL and also create the ImageIcon. Then, I pass the ImageIcon back to the Applet as a serialized object. That works fine...no problems there.
The second solution that I wanted to try was to come up with a more generic and reusable approach, in which I could pass a URL to a servlet, and simply return a stream, and allow the applet to process that stream as it needs, assuming it would know what it was getting from that URL. This would be more usable than the specific approach of only allowing ImageIcon retrieval. I suppose this is actually more of a proxy. The problem is that the first few "lines" of the image are fine (the first array of buffered bytes, it seems) but the rest is garbled and pixelated, and I don't know why. Moreover, the corruption of the image differs every time I query the server.
Here are the relevant code snippets:
=====================Servlet====================
    /* Get the URL String from the request parameters; This is a WMS
     * HTTP request such as follows:
     * http://www.geographynetwork.com/servlet/com.esri.wms.Esrimap?
     *      VERSION=1.1.0&REQUEST=GetMap&SRS=EPSG:4326&
     *      BBOX=-111.11361,3.5885315,-48.345818,71.141304&
     *      HEIGHT=480&...more params...
     * It returns an image (JPEG, JPG, GIF, etc.)
    String urlString =
        URLDecoder.decode(request.getParameter("wmsServer"),
                          "UTF-8");
    URL url = new URL(urlString);
    log("Request parameter: wmsServer = " + urlString);
    //Open and instantiate the streams
    InputStream urlInputStream = url.openStream();
    BufferedInputStream bis = new
        BufferedInputStream(urlInputStream);
    BufferedOutputStream bos = new
        BufferedOutputStream(response.getOutputStream());
    //Read the bytes from the in-stream, and immediately write them
    //out to the out-stream
    int read = 0;
    byte[] buffer = new byte[1024];
    while((read = bis.read(buffer, 0, buffer.length)) != -1) {
        bos.write(buffer, 0, buffer.length);
    //Flush and close
    bos.flush();
    urlInputStream.close();
    bis.close();
    bos.close();
    .=====================Applet=====================
    //Connect to the Servlet
    URLConnection conn = url.openConnection();
    conn.setUseCaches(false);
    conn.setRequestProperty("header", "value");
    conn.setDoOutput(true);
    //Write the encoded WMS HTTP request
    BufferedWriter out =
        new BufferedWriter( new OutputStreamWriter(
            conn.getOutputStream() ) );
    out.write("wmsServer=" + URLEncoder.encode(urlString, "UTF-8"));
    out.flush();
    out.close();
    //Setup the streams to process the servlet response
    BufferedInputStream bis = new
        BufferedInputStream(conn.getInputStream());
    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    //Read the bytes and immediately write to the out-stream
    int read = 0;
    byte[] buffer = new byte[1024];
    while((read = bis.read(buffer, 0, buffer.length)) != -1) {
        bos.write(buffer, 0, buffer.length);
    //Flush and close
    bis.close();</code>
    bos.flush();</code>
    byte[] imageBytes = bos.toByteArray();
    //Create the Image/ImageIcon
    Toolkit tk = Toolkit.getDefaultToolkit();
    Image image = tk.createImage(imageBytes);
    imageIcon = new ImageIcon(image);
    Could this be an offset problem in my buffers? Is there some sort of encoding/decoding I am missing somewhere?
Thanks!
Ben

Answer 1

Without having a probing look, I was wondering why you do the following...
while((read = bis.read(buffer, 0, buffer.length)) != -1) {
bos.write(buffer, 0, buffer.length);
while((read = bis.read(buffer, 0, buffer.length)) != -1) {
bos.write(buffer, 0, buffer.length);
}Your int 'read' holds the number of bytes read in but you then specify buffer.length in your write methods?!? why not use read? otherwise you will be writing the end of the buffer to your stream which contains random memory addresses. I think thats right anyway...
Rob.