后台使用multipart/form-data方式提交数据_后端提交multipart/form-data

 protected string CreateFormDateResponse(string url, Encoding encoding, IDictionary<string, string> textParams, IDictionary<string, FileinFo> fileParams)
    {
        try
        {
            HttpWebRequest request;          
            // 重新设置请求头
            request = (HttpWebRequest)WebRequest.Create(url);
            string host = url.Replace("http://", "").Replace("https://", "");
            host = host.Remove(host.IndexOf('/'));
            request.Host = host;   
            request.Accept = "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8;";
            request.KeepAlive = true;         
            request.Referer = url;
            request.ProtocolVersion = HttpVersion.Version11;
            request.Method = "POST";
            string boundary = DateTime.Now.Ticks.ToString("X"); // 随机分隔线
            request.ContentType = "multipart/form-data;charset=gb2312;boundary=" + boundary;
            request.UserAgent = "Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; LCTE; rv:11.0) like Gecko";
            request.Timeout = 5000;        
            request.Headers["Upgrade-Insecure-Requests"] = "1";
            request.Headers["Accept-Encoding"] = "gzip, deflate";
            request.Headers["Accept-Language"] = "zh-CN,zh;q=0.9";
            request.Headers["Cache-Control"] = "no-cache";
            request.Headers["Pragma"] = "no-cache";
            // 自动追踪30X跳转
            request.AllowAutoRedirect = true;
            byte[] itemBoundaryBytes = encoding.GetBytes("\r\n--" + boundary + "\r\n");
            byte[] endBoundaryBytes = encoding.GetBytes("\r\n--" + boundary + "--\r\n");
            // 组装文本请求参数
            string textTemplate = "Content-Disposition:form-data;name=\"{0}\"\r\n\r\n{1}";
            IEnumerator<KeyValuePair<string, string>> textEnum = textParams.GetEnumerator();
            using (System.IO.Stream reqStream = request.GetRequestStream())
            {
                while (textEnum.MoveNext())
                {
                    string textEntry = string.Format(textTemplate, textEnum.Current.Key, textEnum.Current.Value);
                    byte[] itemBytes = encoding.GetBytes(textEntry);
                    reqStream.Write(itemBoundaryBytes, 0, itemBoundaryBytes.Length);
                    reqStream.Write(itemBytes, 0, itemBytes.Length);
                }
 
                // 组装文件请求参数
                string fileTemplate = "Content-Disposition:form-data;name=\"{0}\";filename=\"{1}\"\r\nContent-Type:{2}\r\n\r\n";
                IEnumerator<KeyValuePair<string, FileinFo>> fileEnum = fileParams.GetEnumerator();
                while (fileEnum.MoveNext())
                {
                    string key = fileEnum.Current.Key;
                    FileinFo fileItem = fileEnum.Current.Value;
                    string fileEntry = string.Format(fileTemplate, key, fileItem.filename, fileItem.ContentType);
                    byte[] itemBytes = encoding.GetBytes(fileEntry);
                    reqStream.Write(itemBoundaryBytes, 0, itemBoundaryBytes.Length);
                    reqStream.Write(itemBytes, 0, itemBytes.Length);
                    byte[] fileBytes = fileItem.data;
                    reqStream.Write(fileBytes, 0, fileBytes.Length);
                }
                reqStream.Write(endBoundaryBytes, 0, endBoundaryBytes.Length);
                reqStream.Close();
            }
            ServicePointManager.DefaultConnectionLimit = 200;
            using (HttpWebResponse rsp = (HttpWebResponse)request.GetResponse())
            {              
                try
                {  // 以字符流的方式读取HTTP响应
                    using (Stream stream = rsp.GetResponseStream())
                    {
                        using (StreamReader reader = new StreamReader(stream, encoding))
                        {
                            return reader.ReadToEnd();
                        }
                    }
                       
                }
                catch (Exception ex)
                {
                    LogInfo.Error("响应文本错误", ex);
                    return null;
                }
                finally
                {
                    // 释放资源                 
                    if (rsp != null) rsp.Close();
                }
            }
        }
        catch (WebException e)
        {
            LogInfo.Error("WebException异常url=" + url + ";\r\ndatabuffer=", e);          
            return string.Empty;
        }
        catch (Exception e)
        {
            LogInfo.Error("异常url=" + url, e);
            return string.Empty;
        }
    }   
    public class FileinFo
    {
        public string name { set; get; }
        public string filename { set; get; }
        public string ContentType { set; get; }
        public byte[] data { set; get; }
    }