C#.NET使用multipart/form-data方式上传文件及其他数据

 

请求发起

.NET Framework 3.5 版

        const string CRLF = "\r\n";

        /// <summary>
        /// 使用multipart/form-data方式上传文件及提交其他数据
        /// </summary>
        /// <param name="headers">请求头参数</param>
        /// <param name="nameValueCollection">键值对参数</param>
        /// <param name="fileCollection">文件参数：参数名，文件路径</param>
        /// <returns>接口返回结果</returns>
        public static string UploadMultipartFormData(string url, string httpMethod, Dictionary<string, string> headers, NameValueCollection nameValueCollection, NameValueCollection fileCollection)
        {
            var boundary = string.Format("batch_{0}", Guid.NewGuid());
            var startBoundary = string.Format("--{0}", boundary);

            // Set up Request body.
            WebRequest request = HttpWebRequest.Create(url);
            foreach (var item in headers)
            {
                request.Headers.Add(item.Key, item.Value);
            }
            request.Method = httpMethod;

            request.ContentType = $"multipart/form-data; boundary={boundary}";

            // Writes the boundary and Content-Disposition header, then writes
            // the file binary, and finishes by writing the closing boundary.
            using (Stream requestStream = request.GetRequestStream())
            {
                StreamWriter writer = new StreamWriter(requestStream);

                // 处理文件内容
                string[] fileKeys = fileCollection.AllKeys;
                foreach (string key in fileKeys)
                {
                    WriteFileToStream(writer, startBoundary, key, fileCollection[key]);
                }

                // 键值对参数
                string[] allKeys = nameValueCollection.AllKeys;
                foreach (string key in allKeys)
                {
                    WriteNvToStream(writer, startBoundary, key, nameValueCollection[key]);
                }

                var endFormData = CRLF + string.Format("--{0}--", boundary) + CRLF;

                writer.Write(endFormData);
                writer.Flush();
                writer.Close();
            }

            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            string json = new StreamReader(response.GetResponseStream()).ReadToEnd();

            return json;
        }

        static void WriteFileToStream(StreamWriter writer, string startBoundary, string name, string filePath)
        {
            var filename = Path.GetFileName(filePath);
            var fileRequestBody = startBoundary + CRLF;
            fileRequestBody += $"Content-Disposition: form-data; name=\"{name}\"; filename=\"{filename}\"" + CRLF + CRLF;

            writer.Write(fileRequestBody);
            writer.Flush();

            byte[] bmpBytes = File.ReadAllBytes(filePath);
            writer.BaseStream.Write(bmpBytes, 0, bmpBytes.Length);
        }

        static void WriteNvToStream(StreamWriter writer, string startBoundary, string name, string value)
        {
            var nvFormData = CRLF + startBoundary + CRLF;
            nvFormData += $"Content-Disposition: form-data; name=\"{name}\"" + CRLF + CRLF;
            nvFormData += value /*+ CRLF*/;

            writer.Write(nvFormData);
            writer.Flush();
        }

 

.NET Framework 4.+ 版

 1         /// <summary>
 2         /// 使用multipart/form-data方式上传文件及其他数据
 3         /// </summary>
 4         /// <param name="headers">请求头参数</param>
 5         /// <param name="nameValueCollection">键值对参数</param>
 6         /// <param name="fileCollection">文件参数：参数名，文件路径</param>
 7         /// <returns>接口返回结果</returns>
 8         public static string PostMultipartFormData(string url, Dictionary<string, string> headers, NameValueCollection nameValueCollection, NameValueCollection fileCollection)
 9         {
10             using (var client = new HttpClient())
11             {
12                 foreach (var item in headers)
13                 {
14                     client.DefaultRequestHeaders.Add(item.Key, item.Value);
15                 }
16 
17                 using (var content = new MultipartFormDataContent())
18                 {
19                     // 键值对参数
20                     string[] allKeys = nameValueCollection.AllKeys;
21                     foreach (string key in allKeys)
22                     {
23                         var dataContent = new ByteArrayContent(Encoding.UTF8.GetBytes(nameValueCollection[key]));
24                         dataContent.Headers.ContentDisposition = new ContentDispositionHeaderValue("form-data")
25                         {
26                             Name = key
27                         };
28                         content.Add(dataContent);
29                     }
30 
31                     //处理文件内容
32                     string[] fileKeys = fileCollection.AllKeys;
33                     foreach (string key in fileKeys)
34                     {
35                         byte[] bmpBytes = File.ReadAllBytes(fileCollection[key]);
36                         var fileContent = new ByteArrayContent(bmpBytes);//填充文件字节
37                         fileContent.Headers.ContentDisposition = new ContentDispositionHeaderValue("form-data")
38                         {
39                             Name = key,
40                             FileName = Path.GetFileName(fileCollection[key])
41                         };
42                         content.Add(fileContent);
43                     }
44 
45                     var result = client.PostAsync(url, content).Result;//post请求
46                     string data = result.Content.ReadAsStringAsync().Result;
47                     return data;//返回操作结果
48                 }
49             }
50         }

 

 

Web API 接收接口

ASP .NET Core Web API 接口接收 multipart/form-data 文件、数据

        [HttpPost]
        //public string Post([FromForm] string directory, [FromForm] IList<IFormFile> files )
        public string Post([FromForm] string directory, [FromForm] IFormFile files)
        {
            return "";
        }

        [HttpPut]
        public string Put([FromForm] IFormFile templateFile, [FromForm] string id, [FromForm] string objectVersionNumber)
        {
            return "";
        }

 

ASP.NET 4.x 版

        [HttpPost(Name = "PostWeatherForecast")]
        //public string Post([FromForm] string directory, [FromForm] IList<IFormFile> files )
        public string Post([FromForm] string directory, [FromForm] IFormFile files)
        {
            // Check if the request contains multipart/form-data.
            if (!Request.ContentType.IsMimeMultipartContent())
            {
                throw new HttpResponseException(HttpStatusCode.UnsupportedMediaType);
            }

            string root = Request.HttpContext.Current.Server.MapPath("~/App_Data");
            var provider = new MultipartFormDataStreamProvider(root);

            try
            {
                // Read the form data.
                await Request.Content.ReadAsMultipartAsync(provider);

                // This illustrates how to get the file names.
                //foreach (MultipartFileData file in provider.FileData)
                //{
                //    Trace.WriteLine(file.Headers.ContentDisposition.FileName);
                //    Trace.WriteLine("Server file path: " + file.LocalFileName);
                //}
                //  return Request.CreateResponse(HttpStatusCode.OK);
            }
            catch (System.Exception e)
            {
                //  return Request.CreateErrorResponse(HttpStatusCode.InternalServerError, e);
            }

            return "";
        }

 

 

 

 https://docs.microsoft.com/zh-cn/aspnet/web-api/overview/advanced/sending-html-form-data-part-2

ASP.NET Core Web API上传多个文件和JSON数据的方法及代码