String sendfile (String filename, String filepath) throws IOException {
    String boundary = Long.toHexString(System.currentTimeMillis());
    String charset = "UTF-8";
    URL url = new URL("...");
    File file = new File(filepath);
    HttpURLConnection con = (HttpURLConnection) url.openConnection();
    con.setRequestMethod("POST");
    con.setUseCaches(false);
    con.setDoOutput(true);
    con.setDoInput(true);
    con.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + boundary);
    OutputStream os = con.getOutputStream();
    PrintWriter writer = new PrintWriter(new OutputStreamWriter(os, charset), true);

    writer.println("--" + boundary);
    writer.println("Content-Disposition: form-data; name="key"");
    writer.println();
    writer.println(key);

    writer.println("--" + boundary);
    writer.println("Content-Disposition: form-data; name="client_id"");
    writer.println();
    writer.println(client_id);

    writer.println("--" + boundary);
    writer.println("Content-Disposition: form-data; name="direction_id"");
    writer.println();
    writer.println(direction_id);

    writer.println("--" + boundary);
    writer.println("Content-Disposition: form-data; name="client_files"; filename="" + filename + """);
    writer.println("Content-Type: image/jpg");
    writer.println();
    BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream(file)));
    for (String line; (line = reader.readLine()) != null; ) writer.println(line);
    writer.println("--" + boundary + "--");
    os.flush();
    os.close();
    BufferedReader in = new BufferedReader(
            new InputStreamReader(
                    con.getInputStream()));
    return in.readLine();
}