MultipartFormDataMemoryStreamProvider修正以支持非IIS宿主的情况

最近做上传，发现以前写的《WebAPI通过multipart/form-data方式接收文件时由开发自行决定如何保存文件》在owin下会取不到文件，所以这里重新修正了下，具体代码如下

    using System.IO;    using System.Net.Http;    using System.Net.Http.Headers;    public class MultipartFormDataMemoryStreamProvider : MultipartFormDataStreamProvider    {        public MultipartFormDataMemoryStreamProvider()            : base("/")        {        }        public override Stream GetStream(HttpContent parent, HttpContentHeaders headers)        {            if (parent == null)            {                throw new ArgumentNullException("parent");            }            if (headers == null)            {                throw new ArgumentNullException("headers");            }            MemoryStream stream = new MemoryStream();            if (IsFileContent(parent, headers))            {                MultipartFileData item = new MultipartFileDataStream(headers, string.Empty, stream);                this.FileData.Add(item);            }            return stream;        }        private bool IsFileContent(HttpContent parent, HttpContentHeaders headers)        {            ContentDispositionHeaderValue contentDisposition = headers.ContentDisposition;            if (contentDisposition == null)            {                throw new InvalidOperationException("Content-Disposition error");            }            return !string.IsNullOrEmpty(contentDisposition.FileName);        }    }    public class MultipartFileDataStream : MultipartFileData, IDisposable    {        /// <summary>        /// file content stream        /// </summary>        public Stream Stream { get; private set; }        public MultipartFileDataStream(HttpContentHeaders headers, string localFileName, Stream stream)            : base(headers, localFileName)        {            if (stream == null)            {                throw new ArgumentNullException("stream");            }            this.Stream = stream;        }        public void Dispose()        {            this.Stream.Dispose();        }    }

使用方式基本没变化，只是取Stream的地方有所调整

if (!Request.Content.IsMimeMultipartContent()){    throw new HttpResponseException(HttpStatusCode.UnsupportedMediaType);}Dictionary<string, string> dic = new Dictionary<string, string>();#region 原来使用MultipartFormDataStreamProvider的方式//string root = HttpContext.Current.Server.MapPath("~/App_Data");//指定要将文件存入的服务器物理位置//var provider = new MultipartFormDataStreamProvider(root);#endregionstring root = AppDomain.CurrentDomain.BaseDirectory;var provider = new MultipartFormDataMemoryStreamProvider();try{    // Read the form data.    await Request.Content.ReadAsMultipartAsync(provider);    // This illustrates how to get the file names.    foreach (MultipartFileData file in provider.FileData)    {//接收文件        Trace.WriteLine(file.Headers.ContentDisposition.FileName);//获取上传文件实际的文件名        Trace.WriteLine("Server file path: " + file.LocalFileName);//获取上传文件在服务上默认的文件名        var stream = ((MultipartFileDataStream)file).Stream;        using (StreamWriter sw = new StreamWriter(Path.Combine(root, file.Headers.ContentDisposition.FileName)))        {            stream.CopyTo(sw.BaseStream);            sw.Flush();        }    }    foreach (var key in provider.FormData.AllKeys)    {//接收FormData        dic.Add(key, provider.FormData[key]);        Console.WriteLine($"Key:{key}  Value:{provider.FormData[key]}");    }}catch(Exception ex){    throw;}