Android : Using Android app and php script to upload files to server

I'm building an Android recorder app, and trying to upload these files to a server using a php script, something I am completely unfamiliar with. I'm using this website as my guide: http://androidexample.com/Upload_File_To_Server_-_Android_Example/index.php?view=article_discription&aid=83&aaid=106

Currently, I get an upload successful message, but then there doesn't appear to be an uploaded file on the server. Perhaps I'm looking in the wrong place? If my php script says $file_path = "uploads/"; and my php script is in var/www/sub/fileupload.php, where on the path should I expect my file to upload to?

Alternatively, I suspect there's an issue with the line where I'm actually uploading the file. The example says

dos.writeBytes("Content-Disposition: form-data; name="uploaded_file";filename=""+ fileName + """ + lineEnd);

This line clearly has some kind of issue with quote matching: maybe a typo? Maybe a lack of escape? Also uploaded_file is undefined. I can adjust it, but I don't understand what the different fields are. To get it to run, I changed it to:

dos.writeBytes("Content-Disposition: form-data; name="+ fileName + ";filename="+ fileName + lineEnd);

This makes it run, but feels off to me. The relevant chunk of code is:

            try {

            // open a URL connection to the Servlet
            FileInputStream fileInputStream = new FileInputStream(sourceFile);
            URL url = new URL(upLoadServerUri);

            // Open a HTTP  connection to  the URL
            // See http://developer.android.com/reference/java/net/HttpURLConnection.html
            conn = (HttpURLConnection) url.openConnection();
            conn.setDoInput(true); // Allow Inputs
            conn.setDoOutput(true); // Allow Outputs
            conn.setUseCaches(false); // Don't use a Cached Copy
            conn.setRequestMethod("POST");
            conn.setRequestProperty("Connection", "Keep-Alive");
            conn.setRequestProperty("ENCTYPE", "multipart/form-data");
            conn.setRequestProperty("Content-Type", "multipart/form-data;boundary=" + boundary);
            conn.setRequestProperty("uploaded_file", fileName);

            dos = new DataOutputStream(conn.getOutputStream());

            dos.writeBytes(twoHyphens + boundary + lineEnd);
            dos.writeBytes("Content-Disposition: form-data; name="uploaded_file";filename=""
                            + fileName + """ + lineEnd);
            dos.writeBytes(lineEnd);

            // create a buffer of  maximum size
            bytesAvailable = fileInputStream.available();

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

            // read file and write it into form...
            bytesRead = fileInputStream.read(buffer, 0, bufferSize);

            while (bytesRead > 0) {

                dos.write(buffer, 0, bufferSize);
                bytesAvailable = fileInputStream.available();
                bufferSize = Math.min(bytesAvailable, maxBufferSize);
                bytesRead = fileInputStream.read(buffer, 0, bufferSize);

            }

            // send multipart form data necesssary after file data...
            dos.writeBytes(lineEnd);
            dos.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd);

            // Responses from the server (code and message)
            serverResponseCode = conn.getResponseCode();
            String serverResponseMessage = conn.getResponseMessage();

            Log.i("uploadFile", "HTTP Response is : " + serverResponseMessage + ": " + serverResponseCode);

            if(serverResponseCode == 200){

                runOnUiThread(new Runnable() {
                    public void run() {

                        String msg = "File Upload Completed.";

                        upload_status.setText(msg);
                        Toast.makeText(RecordActivity.this, "File Upload Complete.",
                                Toast.LENGTH_SHORT).show();
                    }
                });
            }

            //close the streams //
            fileInputStream.close();
            dos.flush();
            dos.close();

Note: this question is extremely similar to Android fileupload not working, but I found the answers unhelpful.