之前调用 WebService 都是直接添加服务引用，然后调用 WebService 方法的，最近发现还可以使用 Http 请求调用 WebService。这里还想说一句，还是 web api 的调用简单。

WebService 服务端代码：

　　 public class WebServiceDemo : System.Web.Services.WebService    {        [WebMethod]        public string HelloWorld()        {            return "Hello World";        }        [WebMethod]        public string Sum(string param1, string param2)        {            int num1 = Convert.ToInt32(param1);            int num2 = Convert.ToInt32(param2);            int sum = num1 + num2;            return sum.ToString();        }    }

很简单的代码，只是用于演示。

客户端调用代码：

　　 class Program    {        static void Main(string[] args)        {            Program program = new Program();            string url = ";;            string method = "Sum";            string num1 = "1";            string num2 = "2";            string result = program.HttpPostWebService(url, method, num1, num2);            Console.WriteLine(result);            Console.ReadKey();        }        public string HttpPostWebService(string url,string method,string num1,string num2)        {            string result = string.Empty;            string param = string.Empty;            byte[] bytes = null;            Stream writer = null;            HttpWebRequest request = null;            HttpWebResponse response = null;            param = HttpUtility.UrlEncode("param1") + "=" + HttpUtility.UrlEncode(num1) + "&" + HttpUtility.UrlEncode("param2") + "=" + HttpUtility.UrlEncode(num2);            bytes = Encoding.UTF8.GetBytes(param);            request = (HttpWebRequest)WebRequest.Create(url + "/" + method);            request.Method = "POST";            request.ContentType = "application/x-www-form-urlencoded";            request.ContentLength = bytes.Length;            try            {                writer = request.GetRequestStream();        //获取用于写入请求数据的Stream对象            }            catch (Exception ex)            {                return "";            }            writer.Write(bytes, 0, bytes.Length);       //把参数数据写入请求数据流            writer.Close();            try            {                response = (HttpWebResponse)request.GetResponse();      //获得响应            }            catch (WebException ex)            {                return "";            }            #region 这种方式读取到的是一个返回的结果字符串            Stream stream = response.GetResponseStream();        //获取响应流            XmlTextReader Reader = new XmlTextReader(stream);            Reader.MoveToContent();            result = Reader.ReadInnerXml();            #endregion            #region 这种方式读取到的是一个Xml格式的字符串            //StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.UTF8);            //result = reader.ReadToEnd();            #endregion             response.Dispose();            response.Close();            //reader.Close();            //reader.Dispose();            Reader.Dispose();            Reader.Close();            stream.Dispose();            stream.Close();            return result;        }    }

第一种读取方式的返回结果：

第二种读取方式的返回结果：

PS：如果遇到调用时报错，可以尝试在服务端（即WebService）的 web.config 配置中添加如下配置节点。

　<system.web>    <webServices>      <protocols>        <add name="HttpPost" />      </protocols>    </webServices>  </system.web>