How to read Image (or other File) in a Servlet and encode it to base64 [duplicate]

Answer 1

protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    FileInputStream in = null;
    try {
        File file = new File(getServletContext().getRealPath("/<thePath>/<fileName>"));
        ByteBuffer buff = ByteBuffer.wrap(new byte[(int)image.length() + (image.length() % 1024 > 0 ? 1024 : 0)]);
        byte[] b = new byte[1024]; 
        in = new FileInputStream(file);
        while(in.read(b) != -1) {
            buff.put(b);
        }
        response.getWriter().write(Base64.encode(buff.array()));
    } catch(Exception e) {
        String msg = "Fehler beim lesen des Bildes";
        LOG.log(Level.SEVERE, msg, e);
        response.sendError(500, msg);
        return;
    } finally {
        if(in != null) in.close();
    }
}

CAUTION! This should only work for files up to 2GB: setting capacity of ByteBuffer only takes an int.

Answer 2

Why so complicated and why read the complete image into memory? A much simpler solution:

protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 
    sun.misc.BASE64Encoder enc = new sun.misc.BASE64Encoder();
    enc.encode(new FileInputStream("/path/to/file.whatever"), response.getOutputStream());
}