public class WebServiceHelper {  /// <summary>  /// Soap協議Post方法  /// </summary>  /// <param name="uri">WebService地址</param>  /// <param name="str">傳入Soap協議格式數據</param>  /// <returns></returns>  public static string SendToReturn(Uri _uri, string _str)  {   string _returnstr = "";   //發起請求   WebRequest webRequest = WebRequest.Create(_uri);   webRequest.ContentType = "text/xml; charset=utf-8";   webRequest.Method = "POST";   using (Stream requestStream = webRequest.GetRequestStream())   {    byte[] paramBytes = Encoding.UTF8.GetBytes(_str);    requestStream.Write(paramBytes, 0, paramBytes.Length);   }   //響應   try   {    WebResponse webResponse = webRequest.GetResponse();    using (StreamReader myStreamReader = new StreamReader(webResponse.GetResponseStream(), Encoding.UTF8))    {     _returnstr = myStreamReader.ReadToEnd();    }   }   catch (WebException ex)   {    _returnstr = new StreamReader(ex.Response.GetResponseStream()).ReadToEnd();   }   return _returnstr;  } }