使用HttpWebRequest出错时获取详细的错误信息

使用HttpWebRequest出错时获取详细的错误信息:

try
    {
     //HttpWebRequest 相关代码
    }
     catch(WebException ex)
    {  
       HttpWebResponse res = ex.Response as HttpWebResponse;
      string strError="";
       if (res.StatusCode == HttpStatusCode.InternalServerError)
       {
         Stream s = res.GetResponseStream();
         StreamReader objReader = new StreamReader(s, System.Text.Encoding.UTF8);
         strError = objReader.ReadToEnd();
         objReader.Close();
       }
       else
       {
         strError = ex.Message;
       }
    //打印strError
    }