Retrieve image from my sql in GWT - image

Question

I am working on GWT RPC. I am facing a problem in retrieving image from my SQL.
Here is my code:
Base64 bas = new Base64();
// sun.misc.BASE64Encoder enc = new sun.misc.BASE64Encoder();
UploadfileJpaController up = new UploadfileJpaController();
// this function returns the value in blob field in the form of byte array
byte[] b = up.findUploadfile(n);
String base64Contents = enc.encode(b).replaceAll("\\s+", "");
//String base64 = Base64Utils.toBase64(b);
base64Contents = "data:image/gif;base64,"+base64Contents;
return base64Contents;
But this is not working.. the image is not displayed. Please help :(

Answer 1

You should let a regular servlet take care of returning the image data, and not use GWT-RPC. The servlet should set the proper image/gif header and write the binary data to the response outputstream.
EDIT
This should look somewhat like this
public class FileDownloadServlet extends HttpServletv {
// This method is called by the servlet container to process a GET request.
public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
// Set content type
resp.setContentType("image/gif");
//Up to you!
byte[] binaryData = getDataFromDbase();
ByteArrayInputStream bis = new ByteArrayInputStream(binaryData);
OutputStream out = resp.getOutputStream();
// Copy the contents of the file to the output stream
byte[] buf = new byte[1024];
int count = 0;
while ((count = bis.read(buf)) >= 0) {
out.write(buf, 0, count);
}
bis.close();
out.close();
}
}
You url is going to be something like
http://server/application/image_servlet?id=123545 where you use the id parameter in the servlet to look up the image. And of course add the servlet to you web.xml. Good luck.