Send file and message from Android to a server

I use the following method to send a file to a server, I receive it with PHP in the variable $ _FILE, the truth is that I do not understand this method 100% and I do not know if I can add more data, I would like to send it together to file a couple of texts like those that are usually sent by post and receive with the variable $ _POST, is there a way to modify this code and achieve it?

public String postArchivo(String pathToOurFile) {
    HttpURLConnection conn = null;
    DataOutputStream outputStream = null;
    DataInputStream inputStream = null;
    String lineEnd = "\r\n";
    String twoHyphens = "--";
    String boundary = "*****";

    int bytesRead, bytesAvailable, bufferSize;
    byte [] buffer;
    int maxBufferSize = 1 * 1024 * 1024;

    try {
        FileInputStream fileInputStream = new FileInputStream(new File(pathToOurFile));
        URL url = new URL(context.getResources().getString(R.string.url_base) + "audio");
        conn = (HttpURLConnection) url.openConnection();

        conn.setDoInput(true);
        conn.setDoOutput(true);
        conn.setUseCaches(false);

        conn.setRequestMethod("POST");
        conn.setRequestProperty("Connection", "Keep-Alive");
        conn.setRequestProperty("Content-Type", "multipart/form-data;boundary=" + boundary);

        outputStream = new DataOutputStream(conn.getOutputStream());
        outputStream.writeBytes(twoHyphens + boundary + lineEnd);
        outputStream.writeBytes("Content-Disposition: form-data; name=\"uploadedfile\";filename=\""
                + pathToOurFile + "\"" + lineEnd);
        outputStream.writeBytes(lineEnd);

        bytesAvailable = fileInputStream.available();
        bufferSize = Math.min(bytesAvailable, maxBufferSize);
        buffer = new byte[bufferSize];

        bytesRead = fileInputStream.read(buffer, 0, bufferSize);

        while(bytesRead > 0) {
            outputStream.write(buffer, 0, bufferSize);
            bytesAvailable = fileInputStream.available();
            bufferSize = Math.min(bytesAvailable, maxBufferSize);
            bytesRead = fileInputStream.read(buffer, 0, bufferSize);
        }

        outputStream.writeBytes(lineEnd);
        outputStream.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd);

        /*int serverResponseCode = conn.getResponseCode();
        String serverResponseMessage = conn.getResponseMessage();

        return serverResponseMessage;*/

        BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
        String line;
        String respost = "";
        while((line = in.readLine()) != null) {
            respost += line;
        }
        return respost;
    }
    catch(Exception e) {
        return "Error: " + e;
    }
    finally {
        if(conn != null)
            conn.disconnect();
    }
}