C#调用JS的WebService的方法返回null

连上了别人的VPN后，使用WebService测试软件测试了一下，结果正常，但是当我在vs里面添加WebService服务，调用的时候就出现了问题，问题如下图：

后来问了一下服务端那边的同事，他们说服务是用JS写的，使用JS和JAVA调用没有问题。

然后我用JS调用试了一下，一点问题都没有，返回的结果和测试软件是一样的，都是xml字符串。

经过很多次百度之后，通过JS调用webservice大概知道了C#调用webservice返回null的原因：因为C#调用webservice的方法返回了一个自定义的对象，在C#自己解析xml字符串的时候没有成功，所以返回null。

自己的解决办法是：借鉴JS调用webservice方法，在C#通过发送HttpPost请求来调用WebService，这个时候返回的就是xml数据了，需要自己解析。代码如下：

        private void MPointHisData(string strid, string startDt, string endDt, string token,int id)
        {
            string ServerPage = "http://XXX/XXX/XXX?wsdl";
            try
            {
                string strXml = "<?xml version='1.0' encoding='utf-8'?>";
                strXml = strXml + "<soap:Envelope xmlns:soap='http://schemas.xmlsoap.org/soap/envelope/' xmlns:impl='http://test.com' xmlns:intf='http://test.com'>";
                strXml = strXml + "<soap:Body>";
                strXml = strXml + "<MPointHisData xmlns='http://test.com'>";
                strXml = strXml + "<id>" + strid + "</id>";
                strXml = strXml + "<startDt>" + startDt + "</startDt>";
                strXml = strXml + "<endDt>" + endDt + "</endDt>";
                strXml = strXml + "<token>" + token + "</token>";
                strXml = strXml + "</MPointHisData>";
                strXml = strXml + "</soap:Body>";
                strXml = strXml + "</soap:Envelope>";
                string res = HttpConnectToServer(ServerPage, strXml);//返回xml形式的数据
                if (res == null || res == "")
                {
                    MessageBox.Show("获取数据失败！");
                    return;
                }
                //解析获取的xml字符串
                XmlDocument doc = new XmlDocument();
                doc.LoadXml(res);
                XmlNode nodebody = doc.GetElementsByTagName("impl:success")[];
                if (nodebody.InnerText == "true")//如果获取到数据
                {
                    foreach (XmlNode resultnode in doc.GetElementsByTagName("impl:result"))
                    {
                        DateTime dataDt = DateTime.Parse(resultnode.ChildNodes[].InnerText);
                        double value = double.Parse(resultnode.ChildNodes[].InnerText);
                        di.WriteHistoryData(id, value,dataDt);
                    }
                }
                else
                {

                }
            }
            catch (Exception ex)
            {

            }
        }
        //发送消息到服务器
        private string HttpConnectToServer(string ServerPage, string strXml)
        {
            byte[] dataArray = Encoding.Default.GetBytes(strXml);
            //创建请求
            HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(ServerPage);
            request.Method = "POST";
            request.ContentLength = dataArray.Length;
            request.ContentType = "application/x-www-form-urlencoded";
            //创建输入流
            Stream dataStream = null;
            try
            {
                dataStream = request.GetRequestStream();
            }
            catch (Exception)
            {
                return null;//连接服务器失败
            }
            //发送请求
            dataStream.Write(dataArray, , dataArray.Length);
            dataStream.Close();
            //读取返回消息
            string res = string.Empty;
            try
            {
                HttpWebResponse response = (HttpWebResponse)request.GetResponse();
                StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.UTF8);
                res = reader.ReadToEnd();
                reader.Close();
            }
            catch (Exception ex)
            {
                return null;//连接服务器失败
            }
            return res;
        }

昨天一天都在纠结调用WebService的事，终于在下班的时候解决了，还好有同事帮帮忙，今天借着程序处理数据的间隙写写昨天处理问题的经过。

当服务发送错误的消息时，客户端获取错误消息如下：

//读取返回消息
            string res = string.Empty;
            HttpWebResponse response;
            try
            {
               response = (HttpWebResponse)request.GetResponse();
                StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.UTF8);
                res = reader.ReadToEnd();
                reader.Close();
            }
            catch (WebException ex)
            {
                response = (HttpWebResponse)ex.Response;

                 StreamReader sr = new StreamReader(response.GetResponseStream(), Encoding.UTF8);

                res = sr.ReadToEnd();

            }            

当服务出现“服务器无法为请求提供服务，因为不支持该媒体类型”时，修改方法如下：

 byte[] dataArray = Encoding.Default.GetBytes(strXml);
            //创建请求
            HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(ServerPage);
            request.Method = "POST";
            request.ContentLength = dataArray.Length;
            request.ContentType = "text/xml;charset=utf-8 "; //修改的地方
            //创建输入流
            Stream dataStream = null;
            try
            {
                dataStream = request.GetRequestStream();
            }
            catch (Exception)
            {
                return null;//连接服务器失败
            }
            //发送请求
            dataStream.Write(dataArray, , dataArray.Length);
            dataStream.Close();
            //读取返回消息
            string res = string.Empty;
            try
            {
                HttpWebResponse response = (HttpWebResponse)request.GetResponse();
                StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.UTF8);
                res = reader.ReadToEnd();
                reader.Close();
            }
            catch (WebException ex)
            {
                HttpWebResponse response = (HttpWebResponse)ex.Response;

                StreamReader sr = new StreamReader(response.GetResponseStream(), Encoding.UTF8);
                res = sr.ReadToEnd();
            }
            return res;