C# - Json POST 请求已发送但未被 PHP 服务器接收

I am sending a HTTP request from a C# windowsform application to PHP server hosted on OpenShift (Redhat). I am using the method POST, with Json data.

问题在于:

• 数据似乎正确发送(我看到了wireshark中的数据包)
• php 脚本正确启动，我在日志中看到收到了一条 POST 消息
• 但是没有收到 POST 数据..

这里是 C# 代码:

string json = "{"user":"test"," +
                ""n":"2"}";

HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://........rhcloud.com/webservices.php");

request.Method = "POST";
request.ContentType = "application/json";
request.ContentLength = json.Length;

using (var streamWriter = new StreamWriter(request.GetRequestStream()))
{
    streamWriter.Write(json);
    streamWriter.Close();

    var httpResponse = (HttpWebResponse)request.GetResponse();
    using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))
    {
         var result = streamReader.ReadToEnd();
         Debug.WriteLine("R : " + result);
    }
}

这是PHP代码:

echo "Start Saving ! ";

// Handle Posted Data From C# App
if (isset($_POST) && !empty($_POST))
{
    echo 'Data Recieved';
}
else
{
  // Error
  echo 'No POST Data Found';
}   

函数总是返回:开始保存！没有找到POST数据".

// Error handling is left as an exercise
$input = json_decode(file_get_contents('php://input'), true);