C# 实现http实现请求请求 HttpWebRequest

    public class XHttpRequest
    {
        //同步方式发起http get请求
        public string HttpGet(string url, string queryString)
        {
            string responseData = null;

            if (!string.IsNullOrEmpty(queryString))
            {
                url += "?" + queryString;
            }

            HttpWebRequest webRequest = WebRequest.Create(url) as HttpWebRequest;
            webRequest.Method = "GET";
            webRequest.ServicePoint.Expect100Continue = false;
            webRequest.Timeout = 20000;

            StreamReader responseReader = null;

            try
            {
                responseReader = new StreamReader(webRequest.GetResponse().GetResponseStream());
                responseData = responseReader.ReadToEnd();
            }
            catch
            {
            }
            finally
            {
                webRequest.GetResponse().GetResponseStream().Close();
                responseReader.Close();
                responseReader = null;
                webRequest = null;
            }

            return responseData;
        }

        //同步方式发起http post请求
        public string HttpPost(string url, string queryString)
        {
            StreamWriter requestWriter = null;
            StreamReader responseReader = null;

            string responseData = null;

            HttpWebRequest webRequest = WebRequest.Create(url) as HttpWebRequest;
            webRequest.Method = "POST";
            webRequest.ContentType = "application/x-www-form-urlencoded";
            webRequest.ServicePoint.Expect100Continue = false;
            webRequest.Timeout = 20000;

            try
            {             
                //POST the data.
                requestWriter = new StreamWriter(webRequest.GetRequestStream());
                requestWriter.Write(queryString);
                requestWriter.Close();
                requestWriter = null;

                responseReader = new StreamReader(webRequest.GetResponse().GetResponseStream());
                responseData = responseReader.ReadToEnd();
            }
            catch
            {
                throw;
            }
            finally
            {
                if (requestWriter != null)
                {
                    requestWriter.Close();
                    requestWriter = null;
                }

                if (responseReader != null)
                {
                    responseReader.Close();
                    responseReader = null;
                }

                webRequest.GetResponse().GetResponseStream().Close();
                webRequest = null;
            }

            return responseData;
        }

        //同步方式发起http post请求，可以同时上传文件
        public string HttpPostWithFile(string url, string queryString, List<Parameter> files)
        {
            Stream requestStream = null;
            StreamReader responseReader = null;
            string responseData = null;
            string boundary = DateTime.Now.Ticks.ToString("x");
            url += '?' + queryString;
            HttpWebRequest webRequest = WebRequest.Create(url) as HttpWebRequest;
            webRequest.ServicePoint.Expect100Continue = false;
            webRequest.Timeout = 20000;
            webRequest.ContentType = "multipart/form-data; boundary=" + boundary;
            webRequest.Method = "POST";
            webRequest.KeepAlive = true;
            webRequest.Credentials = CredentialCache.DefaultCredentials;

            try
            {
                Stream memStream = new MemoryStream();

                byte[] boundarybytes = System.Text.Encoding.ASCII.GetBytes("\r\n--" + boundary + "\r\n");
                string formdataTemplate = "\r\n--" + boundary + "\r\nContent-Disposition: form-data; name=\"{0}\"\r\n\r\n{1}";

                List<Parameter> listParams = HttpUtil.GetQueryParameters(queryString);

                foreach (Parameter param in listParams)
                {
                    string formitem = string.Format(formdataTemplate, param.Name, param.Value);
                    byte[] formitembytes = Encoding.UTF8.GetBytes(formitem);
                    memStream.Write(formitembytes, 0, formitembytes.Length);
                }

                memStream.Write(boundarybytes, 0, boundarybytes.Length);

                string headerTemplate = "Content-Disposition: form-data; name=\"{0}\"; filename=\"{1}\"\r\nContent-Type: \"{2}\"\r\n\r\n";

                foreach (Parameter param in files)
                {
                    string name = param.Name;
                    string filePath = param.Value;
                    string file = Path.GetFileName(filePath);
                    string contentType = HttpUtil.GetContentType(file);

                    string header = string.Format(headerTemplate, name, file, contentType);
                    byte[] headerbytes = System.Text.Encoding.UTF8.GetBytes(header);

                    memStream.Write(headerbytes, 0, headerbytes.Length);

                    FileStream fileStream = new FileStream(filePath, FileMode.Open, FileAccess.Read);
                    byte[] buffer = new byte[1024];
                    int bytesRead = 0;

                    while ((bytesRead = fileStream.Read(buffer, 0, buffer.Length)) != 0)
                    {
                        memStream.Write(buffer, 0, bytesRead);
                    }

                    memStream.Write(boundarybytes, 0, boundarybytes.Length);
                    fileStream.Close();
                }

                webRequest.ContentLength = memStream.Length;

                requestStream = webRequest.GetRequestStream();

                memStream.Position = 0;
                byte[] tempBuffer = new byte[memStream.Length];
                memStream.Read(tempBuffer, 0, tempBuffer.Length);
                memStream.Close();
                requestStream.Write(tempBuffer, 0, tempBuffer.Length);
                requestStream.Close();
                requestStream = null;

                responseReader = new StreamReader(webRequest.GetResponse().GetResponseStream());
                responseData = responseReader.ReadToEnd();
            }
            catch (Exception ex)
            {
            }
            finally
            {
                if (requestStream != null)
                {
                    requestStream.Close();
                    requestStream = null;
                }

                if (responseReader != null)
                {
                    responseReader.Close();
                    responseReader = null;
                }

                webRequest.GetResponse().GetResponseStream().Close();
                webRequest = null;
            }

            return responseData;
        }
    }