接口 Post

 public static StringBuilder HttpPost(string Url, byte[] Postdata, string i)
        {
            StringBuilder content = new StringBuilder();
            try
            {
                WebClient wc = new WebClient();
                wc.Headers.Add("Content-Type", "application/x-www-form-urlencoded");

                byte[] bycontent = wc.UploadData(Url, "POST", Postdata);
                string strcontent = System.Text.Encoding.UTF8.GetString(bycontent);
                //strcontent=strcontent.Replace(""", "“");
                content.Append(strcontent);

            }
            catch (Exception ex)
            {
                throw new ServiceCustomException("HTTP请求失败！", ex);
            }
            return content;
        }

使用：StringBuilder str = NetUtil.HttpPost(posturl, byte1, "1");

// StringBuilder sbd = NetUtil.Request(geturl, HttpMethod.GET);//此方式为Get实例

 /// <summary>
        /// 发出Http请求，并返回服务器的响应
        /// </summary>
        /// <param name="url">请求的网址</param>
        /// <param name="dataToPost">post的数据</param>
        /// <returns>服务器的响应</returns>
        public static StringBuilder Request(string url, HttpMethod method, WebHeaderCollection headers = null, string accept = null,
            string contentType = null, Encoding encoding = null, bool keepAlive = false,
            int timeout = 1000 * 600, int readWriteTimeout = 1000 * 600, int writeCount = 256,
            CookieContainer cookieContainer = null, byte[] dataToPost = null)
        {
            StringBuilder result = new StringBuilder();
            HttpWebRequest request = null;
            HttpWebResponse response = null;
            Stream responseStream = null;
            StreamReader reader = null;

            try
            {
                request = (HttpWebRequest)WebRequest.Create(url);
                request.Method = method.ToString();

                if (headers != null)
                    request.Headers = headers;

                if (!string.IsNullOrEmpty(accept))
                    request.Accept = accept;

                if (!string.IsNullOrEmpty(contentType))
                    request.ContentType = contentType;

                request.KeepAlive = keepAlive;

                if (dataToPost != null && !dataToPost.Length.Equals(0))
                {
                    request.ContentLength = dataToPost.Length;
                }

                request.Timeout = timeout;
                request.ReadWriteTimeout = readWriteTimeout;

                if (encoding == null)
                    encoding = Encoding.GetEncoding("utf-8");

                if (method.Equals(HttpMethod.POST) && dataToPost != null && !dataToPost.Length.Equals(0))
                {
                    using (Stream requestStream = request.GetRequestStream())
                    {
                        int index = 0;

                        while (index < dataToPost.Length)
                        {
                            if (dataToPost.Length - index <= writeCount)
                            {
                                requestStream.Write(dataToPost, index, dataToPost.Length - index);
                                index += dataToPost.Length - index;
                                break;
                            }
                            else
                            {
                                requestStream.Write(dataToPost, index, writeCount);
                                index += writeCount;
                            }
                        }
                    }
                }

                if (cookieContainer == null)
                    request.CookieContainer = new CookieContainer();
                else
                    request.CookieContainer = cookieContainer;

                response = (HttpWebResponse)request.GetResponse();
                responseStream = response.GetResponseStream();
                reader = new StreamReader(responseStream, encoding);

                string line = string.Empty;

                while ((line = reader.ReadLine()) != null)
                {
                    result.Append(line);
                }

                reader.Close();
            }
            catch (WebException ex)
            {
                throw ex;
            }
            catch (Exception ex)
            {

            }
            finally
            {
                if (responseStream != null)
                {
                    responseStream.Close();
                    responseStream = null;
                }
                if (reader != null)
                {
                    reader.Close();
                    reader = null;
                }
                if (response != null)
                {
                    response.Close();
                    response = null;
                }
            }

            return result;
        }

使用： StringBuilder str = NetUtil.Request(posturl, HttpMethod.POST, null, null, "application/x-www-form-urlencoded", System.Text.Encoding.UTF8,
                        dataToPost: byte1);

 /// <summary>
        /// 提交数据请求  方法一
        /// </summary>
        /// <param name="POSTURL">请求提交的地址 如：http://xxx.xxx.xxx/interface/TestPostRequest</param>
        /// <param name="PostData">提交的数据(字符串)</param>
        /// <returns></returns>
        public static string RequestData(string POSTURL, string PostData)
        {
            //发送请求的数据
            WebRequest myHttpWebRequest = WebRequest.Create(POSTURL);
            myHttpWebRequest.Method = "POST";
            UTF8Encoding encoding = new UTF8Encoding();
            byte[] byte1 = encoding.GetBytes(PostData);
            myHttpWebRequest.ContentType = "application/x-www-form-urlencoded";
            //myHttpWebRequest.ContentType = "application/json";
            myHttpWebRequest.ContentLength = byte1.Length;
            Stream newStream = myHttpWebRequest.GetRequestStream();
            newStream.Write(byte1, 0, byte1.Length);
            newStream.Close();

            //发送成功后接收返回的XML信息
            HttpWebResponse response = (HttpWebResponse)myHttpWebRequest.GetResponse();
            string lcHtml = string.Empty;
            Encoding enc = Encoding.GetEncoding("UTF-8");
            Stream stream = response.GetResponseStream();
            StreamReader streamReader = new StreamReader(stream, enc);
            lcHtml = streamReader.ReadToEnd();
            return lcHtml;
        }

使用：NetUtil.RequestData(posturl, json);

public static string BuildQuery(IDictionary<string, string> parameters)
        {
            StringBuilder postData = new StringBuilder();
            bool hasParam = false;

            IEnumerator<KeyValuePair<string, string>> dem = parameters.GetEnumerator();
            while (dem.MoveNext())
            {
                string name = dem.Current.Key;
                string value = dem.Current.Value;
                // 忽略参数名或参数值为空的参数
                if (!string.IsNullOrEmpty(name) && !string.IsNullOrEmpty(value))
                {
                    if (hasParam)
                    {
                        postData.Append("&");
                    }

                    postData.Append(name);
                    postData.Append("=");
                    //postData.Append(UrlEncode(value));
                    postData.Append(value);
                    hasParam = true;
                }
            }

            return postData.ToString();
        }

使用： 

Dictionary<string, string> dic = new Dictionary<string, string>();
                    dic.Add("canshu", "dddddddd);

string str1 = NetUtil.BuildQuery(dic); //dic为要post的所有参数

byte[] byte1 = System.Text.Encoding.UTF8.GetBytes(str1);

//posturl为传递的url参数

第三种方式中json为：string json = "canshu=" + "dddddddd";