C#通过HttpWebRequest调用WebService并获取返回数据

public string GetWebMethodReturn(string url, string methodName, string parms)
    {
        StringBuilder param = new StringBuilder();
        param.AppendLine("<?xml version='1.0' encoding='utf-8'?>");
        param.AppendLine(@"<soap12:Envelope xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' xmlns:xsd='http://www.w3.org/2001/XMLSchema' xmlns:soap12='http://www.w3.org/2003/05/soap-envelope'>");
        param.AppendLine("<soap12:Body>");
        param.AppendLine("<" + methodName + " xmlns='http://tempuri.org/'>");
        param.AppendLine(parms);
        param.AppendLine("</" + methodName + ">");
        param.AppendLine("</soap12:Body>");
        param.AppendLine("</soap12:Envelope>");

        byte[] bs = Encoding.UTF8.GetBytes(param.ToString());

        HttpWebRequest myRequest = (HttpWebRequest)WebRequest.Create(url);
        myRequest.Method = "POST";
        myRequest.ContentType = "application/soap+xml; charset=utf-8";
        myRequest.ContentLength = bs.Length;

        using (Stream reqStream = myRequest.GetRequestStream())
        {
            reqStream.Write(bs, 0, bs.Length);

        }
        string responseString = string.Empty;
        using (HttpWebResponse myResponse = (HttpWebResponse)myRequest.GetResponse())
        {

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