StreamToString

private String streamToString(InputStream inputStream,String charset) {
    try {
        InputStreamReader inputStreamReader = new InputStreamReader(inputStream,charset);

        BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
        String s = null;
        StringBuilder builder = new StringBuilder();
        while ((s = bufferedReader.readLine()) != null){
            builder.append(s);
        }

        bufferedReader.close();
        return builder.toString();

    } catch (Exception e) {
        e.printStackTrace();
    }

    return  null;
}