private void launch_Click(object sender, RoutedEventArgs e)
        {
            string url = "http://asdf.com/SecondTest.php";//这里是php文件所在的位置
            HttpWebRequest myRequest = (HttpWebRequest)WebRequest.Create(url);  
            myRequest.Method = "POST";
            myRequest.ContentType = "application/x-www-form-urlencoded";
            myRequest.BeginGetRequestStream(getRequestCallBack, myRequest);
        }

        private void getRequestCallBack(IAsyncResult result)
        {
            HttpWebRequest request = (HttpWebRequest)result.AsyncState;
            Dispatcher.BeginInvoke(() =>//之所以使用beginInvoke的意义在于下面读取了一个TextBox的Text属性，在WP8中需要使用这个
            {
                string postStr = "textContent=" + newTextMessage.Text;
                using (Stream stream = request.EndGetRequestStream(result))
                {

                    Byte[] postByte;
                    postByte = Encoding.UTF8.GetBytes(postStr);
                    stream.Write(postByte, 0, postByte.Length);
                }
            });
            

                request.BeginGetResponse(ResponseCallback, request);


            //返回应答请求异步操作的状态
           
        }
//下面是从服务器获得数据，以此来检验是否传上去了，当然了，服务器要echo出刚才传入的东西
        private void ResponseCallback(IAsyncResult result)
        {
            string response = null;
            Stream stream = null;

            try
            {
                //获取异步操作返回的的信息 
                HttpWebRequest httpWebRequest = (HttpWebRequest)result.AsyncState;
                //结束对 Internet 资源的异步请求
                WebResponse webResponse = httpWebRequest.EndGetResponse(result);
                stream = webResponse.GetResponseStream();
                using (StreamReader sr = new StreamReader(stream))
                {
                    response = sr.ReadToEnd();
                }
            }
            catch { }
            finally
            {
                if (stream != null)
                {
                    stream.Close();
                }
            }

            //这里不为空代表获得回复了
            if (response != null)
            {
                //因为HttpWebRequest是异步，不在UI线程上。所以要改变UI线程上的控件属性就要用Dispatcher.BeginInvoke()。
                Dispatcher.BeginInvoke(() =>
                {
                    MessageBox.Show(response);
                });
            }

        }
    }

<?php
header("Content-type:application/x-www-form-urlencoded; charset=utf-8");
 
$a=$_POST["userName"];//以此来接收POST得到的数据


$con=mysql_connect("localhost","verssageli","password");
mysql_query("set character set ‘utf-8‘");
if (!$con)
  {
  die(‘Could not connect: ‘ . mysql_error());
  }
  mysql_select_db("verssageli",$con);
mysql_query("INSERT INTO postcontent (username) VALUES (‘$a‘)");//向postcontent表中的username栏插入$a的值
echo $a;//输出$a

mysql_close($con);
?>