How to send an Image from Mongo DB to Ext JS with an Java Servlet

Question

I have an Java Servlet which tries to send an Image from Mongo DB to Ext JS:

@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

    String action = req.getParameter("action");

    if (action != null && action.equals("download")) {

        resp.setContentType("text/html");
        resp.setHeader("Content-Disposition", "attachment;filename=" + "images.jpg");

        try {
            DB db = DataBaseMongoService.getDb("forum_images"); //class that manages Mongo DB access
            GridFS gfs = new GridFS(db, "image");
            GridFSDBFile imageForOutput = gfs.findOne("images.jpg");

            InputStream in = imageForOutput.getInputStream();

            ServletOutputStream out = resp.getOutputStream();
            out.write(IOUtils.toByteArray(in));
            out.flush();
            in.close();
            out.close();

        } catch (UnknownHostException e) {
            e.printStackTrace();
        } catch (NamingException e) {
            e.printStackTrace();
        }
    }
}

My Ext JS call looks like this:

Ext.Ajax.request({
url: 'ForumImageServlet',
method: 'GET',
params: {
    action: 'download'
},});

The Response is the bytestream of the image that looks like this:

����JFIF��� "" $(4,$&1'-=-157:::#+?D?8C49:77%w777777777777777777777777777777777777777777777777��Pp"��ï...

?

How can I get a real image as a response to my servlet? Thanks in advance!

Answer 1

Why do you set ContentType to text/html ?

Try using image/jpg

Answer 2

The final solution was encoding the bytestream to base64:

            byte[] buf = IOUtils.toByteArray(in);

        String prefix = "{\"url\":\"data:image/jpeg;base64,";
        String postfix = "\"}";
        String fileJson = prefix + Base64.encodeBytes(buf).replaceAll("\n", "") + postfix; 
        PrintWriter out = resp.getWriter();
        out.write(fileJson);
        out.flush();
        in.close();
        out.close();

Answer 3

instead of using ajax requests, you can inject an img-tag with src attribute. when you provide the correct mime-type, your browser loads the image