Android, HttpURLConnection, file parameter

-- Not confirmed --
confirmed just 1 file parameter.

public static void sendMultipart(HttpURLConnection connection, String[] filefield, File[] filepath, Map<String, String> textdata) throws IOException {

        final String twoHyphens = "--";
        final String boundary =  "*****"+ UUID.randomUUID().toString()+"*****";
        final String lineEnd = "\r\n";
        final int maxBufferSize = 1024*1024*3;

        DataOutputStream outputStream;

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

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

        outputStream = new DataOutputStream(connection.getOutputStream());
        if(filefield != null) {
            for(int i=0;i<filefield.length;i++){

                String fileKey = filefield[i];
                File filePath = filepath[i];

                outputStream.writeBytes(twoHyphens + boundary + lineEnd);
                outputStream.writeBytes("Content-Disposition: form-data; name=\"" + fileKey + "\"; filename=\"" + filepath[i].getName() + "\"" + lineEnd);
                outputStream.writeBytes("Content-Type: application/octet-stream" + lineEnd);
                outputStream.writeBytes("Content-Transfer-Encoding: binary" + lineEnd);
                outputStream.writeBytes(lineEnd);

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

                int 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);
            }


        }else{

        }
        for (Map.Entry<String, String> entry : textdata.entrySet()) {
            outputStream.writeBytes(twoHyphens + boundary + lineEnd);
            outputStream.writeBytes("Content-Disposition: form-data; name=\"" + entry.getKey() + "\"" + lineEnd);
            outputStream.writeBytes("Content-Type: text/plain"+lineEnd);
            outputStream.writeBytes(lineEnd);
            outputStream.writeBytes(entry.getValue());
            outputStream.writeBytes(lineEnd);
        }

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

        outputStream.close();
    }






https://qiita.com/informationsea/items/778d9525c3aaded73577