Post Json data to PHP using Android [duplicate]

I'm trying to POST data to PHP using Android. But getting Null on receiving in PHP. Here is my Code...

Android Code:

try
{
    JSONStringer().object()

    JSONObject data = new JSONObject();
    data.put("phone", "11");
    data.put("pwd", "aa");

    HttpPost request = new HttpPost("http://www.cslindia.org/viz/test.php");
    request.setHeader("Accept", "application/json");
    request.setHeader("Content-type", "application/json");

    StringEntity entity = new StringEntity(data.toString());
    request.setEntity(entity);

    DefaultHttpClient httpClient = new DefaultHttpClient();
    HttpResponse response = httpClient.execute(request);

    HttpEntity httpEntity =response.getEntity();
    String json = EntityUtils.toString(httpEntity);
    Log.e("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@",json);
}

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

PHP Code:

$json = file_get_content('php://input');
print_r("1".$json); //For Testing Purpose
$jsonObj = json_decode($json, true);
print_r("2".$jsonObj); //For Testing Purpose
$mphone=$jsonObj['phone'];
$mpwd=$jsonObj['pwd'];

But, $json, $jsonObj both have null value. What may be the solution please help me out...