.net 模拟发起HTTP请求（用于上传文件）

　　用C#在服务端发起http请求，附上代码一

    /// <summary>

    /// 文件帮助类

    /// </summary>

    public class FileHelper

    {

        /// <summary>

        /// 上传文件

        /// </summary>

        /// <param name="url">请求地址</param>

        /// <param name="path">文件路径（带文件名）</param>

        /// <returns></returns>

        public static string HttpUploadFile(string url, string path)

        {

            // 设置参数

            HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;

            CookieContainer cookieContainer = new CookieContainer();

            request.CookieContainer = cookieContainer;

            request.AllowAutoRedirect = true;

            request.Method = "POST";

            string boundary = DateTime.Now.Ticks.ToString("X"); // 随机分隔线

            request.ContentType = "multipart/form-data;charset=utf-8;boundary=" + boundary;

            byte[] itemBoundaryBytes = Encoding.UTF8.GetBytes("\r\n--" + boundary + "\r\n");

            byte[] endBoundaryBytes = Encoding.UTF8.GetBytes("\r\n--" + boundary + "--\r\n");

            int pos = path.LastIndexOf("\\");

            string fileName = path.Substring(pos + );

            //请求头部信息

            StringBuilder sbHeader = new StringBuilder(string.Format("Content-Disposition:form-data;name=\"file\";filename=\"{0}\"\r\nContent-Type:application/octet-stream\r\n\r\n", fileName));

            byte[] postHeaderBytes = Encoding.UTF8.GetBytes(sbHeader.ToString());

            StringBuilder builder = new StringBuilder($"Content-Disposition:form-data;name=\"subPath\"\r\n\r\ntmswechat");

            byte[] postHeaderBytestwo = Encoding.UTF8.GetBytes(builder.ToString());

            FileStream fs = new FileStream(path, FileMode.Open, FileAccess.Read);

            byte[] bArr = new byte[fs.Length];

            fs.Read(bArr, , bArr.Length);

            fs.Close();

            Stream postStream = request.GetRequestStream();

            postStream.Write(itemBoundaryBytes, , itemBoundaryBytes.Length);

            postStream.Write(postHeaderBytes, , postHeaderBytes.Length);

            postStream.Write(bArr, , bArr.Length);

            postStream.Write(itemBoundaryBytes, , itemBoundaryBytes.Length);

            postStream.Write(postHeaderBytestwo, , postHeaderBytestwo.Length);

            postStream.Write(endBoundaryBytes, , endBoundaryBytes.Length);

            postStream.Close();

            //发送请求并获取相应回应数据

            HttpWebResponse response = request.GetResponse() as HttpWebResponse;

            //直到request.GetResponse()程序才开始向目标网页发送Post请求

            Stream instream = response.GetResponseStream();

            StreamReader sr = new StreamReader(instream, Encoding.UTF8);

            //返回结果网页（html）代码

            string content = sr.ReadToEnd();

            return content;

        }

        /// <summary>

        /// 上传文件

        /// </summary>

        /// <param name="url">请求地址</param>

        /// <param name="fs">文件流</param>

        /// <param name="fileName">文件名</param>

        /// <returns></returns>

        public static string HttpUploadFile(string url, Stream fs, string fileName)

        {

            // 设置参数

            HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;

            CookieContainer cookieContainer = new CookieContainer();

            request.CookieContainer = cookieContainer;

            request.AllowAutoRedirect = true;

            request.Method = "POST";

            string boundary = DateTime.Now.Ticks.ToString("X"); // 随机分隔线

            request.ContentType = "multipart/form-data;charset=utf-8;boundary=" + boundary;

            byte[] itemBoundaryBytes = Encoding.UTF8.GetBytes("\r\n--" + boundary + "\r\n");

            byte[] endBoundaryBytes = Encoding.UTF8.GetBytes("\r\n--" + boundary + "--\r\n");

            //请求头部信息

            StringBuilder sbHeader = new StringBuilder(string.Format("Content-Disposition:form-data;name=\"file\";filename=\"{0}\"\r\nContent-Type:application/octet-stream\r\n\r\n", fileName));

            byte[] postHeaderBytes = Encoding.UTF8.GetBytes(sbHeader.ToString());

            StringBuilder builder = new StringBuilder($"Content-Disposition:form-data;name=\"subPath\"\r\n\r\ntmswechat");

            byte[] postHeaderBytestwo = Encoding.UTF8.GetBytes(builder.ToString());

            byte[] bArr = new byte[fs.Length];

            int len = fs.Read(bArr, , (int)fs.Length);

            Stream postStream = request.GetRequestStream();

            postStream.Write(itemBoundaryBytes, , itemBoundaryBytes.Length);

            postStream.Write(postHeaderBytes, , postHeaderBytes.Length);

            postStream.Write(bArr, , len);

            postStream.Write(itemBoundaryBytes, , itemBoundaryBytes.Length);

            postStream.Write(postHeaderBytestwo, , postHeaderBytestwo.Length);

            postStream.Write(endBoundaryBytes, , endBoundaryBytes.Length);

            postStream.Close();

            //发送请求并获取相应回应数据

            HttpWebResponse response = request.GetResponse() as HttpWebResponse;

            //直到request.GetResponse()程序才开始向目标网页发送Post请求

            Stream instream = response.GetResponseStream();

            StreamReader sr = new StreamReader(instream, Encoding.UTF8);

            //返回结果网页（html）代码

            string content = sr.ReadToEnd();

            return content;

        }

    }

代码二

　　　　　public static string HttpClientUploadFile(string url, Stream fs, string fileName)

        {

            if (url.StartsWith("https"))

                System.Net.ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls;

            HttpClient httpClient = new HttpClient();

            MultipartFormDataContent formData = new MultipartFormDataContent();

            byte[] bArr = new byte[fs.Length];

            fs.Read(bArr, , (int)fs.Length);

            fs.Seek(, SeekOrigin.Begin);

            ByteArrayContent byteArrayContent = new ByteArrayContent(bArr);

            byteArrayContent.Headers.ContentEncoding.Add("utf-8");

            formData.Add(byteArrayContent, "file", fileName);

            formData.Add(new StringContent("tmswechat"), "subPath");

            HttpResponseMessage response = httpClient.PostAsync(url, formData).Result;

            if (response.IsSuccessStatusCode)

            {

                string result = response.Content.ReadAsStringAsync().Result;

                return result;

            }

            return null;

        }