Android : Problems with sending a string to the server in android?

Good day. It seems to be simple, there is a line json, you want to throw on the server, at what the server does not check the correctness construction line, or something else, just the server and just a string, but the problem is that the server is somehow always returns 0, it means that line, he has not entered. Here's where to send post request addef38885.nichost.ru/and.php?data=. So after all data that is already on the server = will go into a variable. My request is placed within the function and looks

static  String SendJsonViaPost(String url, String json) {
    String responseJson = "";
    HttpClient client = new DefaultHttpClient();
    HttpPost post = new HttpPost(url);
    try {
        StringEntity stringEntity = new StringEntity(json);
        stringEntity.setContentType("application/json");
        post.setEntity(stringEntity);
        HttpResponse response = client.execute(post);
        BufferedReader rd = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
        String line = "";
        while ((line = rd.readLine()) != null) {
            responseJson += line;
        }

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

    return responseJson;}

and here is how I call it:

SendJsonViaPost("http://addef38885.nichost.ru/and.php?data=","testing_file_1");

there is the PHP code of the server.

<?php

 $par = $_POST['data'];

 if ( strlen($par) >=1 )
 {
  $fp = fopen('data/'.date('Ymd_His').'.txt', "a"); // Открываем файл в режиме записи 

  $mytext = $par; // Исходная строка

  $test = fwrite($fp, $mytext); // Запись в файл

  if ($test) { echo '1'; } else { echo '0'; }

  fclose($fp); //Закрытие файла
   }
   else { echo '0'; }

    ?>