MultipartFormDataStreamProvider并追加到现有文件

本文关键字：文件 追加 MultipartFormDataStreamProvider | 更新日期: 2023-09-27 18:15:44

大家好，

我使用ASP.net WebApi来接收来自Cordova应用程序的上传(通过HTTP多部分POST请求发送)。上传是"块"，因此，我需要在第一个块上创建一个文件，然后将每个后续的"块"附加到它。以下是我目前正在处理的内容:

public class CustomMultipartFormDataStreamProvider : MultipartFormDataStreamProvider
{
    public CustomMultipartFormDataStreamProvider(string path) : base(path)
    { }
    public override string GetLocalFileName(System.Net.Http.Headers.HttpContentHeaders headers)
    {
        var name = !string.IsNullOrWhiteSpace(headers.ContentDisposition.FileName) ? headers.ContentDisposition.FileName : "NoName";
        return name.Replace("'"", string.Empty); //this is here because Chrome submits files in quotation marks which get treated as part of the filename and get escaped
    }
}

和控制器中…

    [Route("upload"), HttpGet, HttpPost]
    public void HandleUpload()
    {
        string root = HttpContext.Current.Server.MapPath("~/App_Data/upload-temp");
        if (Request.Content.IsMimeMultipartContent())
        {
            var streamProvider = new Libs.CustomMultipartFormDataStreamProvider(root);
            var task = Request.Content.ReadAsMultipartAsync(streamProvider).ContinueWith(t =>
                {
                    if (t.IsFaulted || t.IsCanceled)
                        throw new HttpResponseException(HttpStatusCode.InternalServerError);
                });
        }
        else
        {
            throw new HttpResponseException(Request.CreateResponse(HttpStatusCode.NotAcceptable, "This request is not properly formatted"));
        }
    }

我假设在CustomMultipartFormDataStreamProvider我会以某种方式覆盖GetStream来完成追加，但对于我的生活不能得到我的头围绕它…

有没有人知道如何做到这一点?

欢呼:)

MultipartFormDataStreamProvider并追加到现有文件

这篇文章正是我正在处理的问题，诀窍是在您的自定义MultipartFormDataStreamProvider中重写GetStream方法。我的解决方案基于System.Net.Http.MultipartFormDataStreamProvider提供程序的源代码。

 public override Stream GetStream(HttpContent parent, HttpContentHeaders headers) {
        if (!headers.ContentDisposition.FileName.HasValue())
            return Stream.Null;
        if (parent == null)
            throw new ArgumentNullException("parent");
        if (headers == null)
            throw new ArgumentNullException("headers");
        var fileName = this.GetLocalFileName(headers);
        if (!fileName.HasValue())
            throw new ArgumentNullException("fileName");
        var file = Path.Combine(this.RootPath, fileName);
        this.FileData.Add(new MultipartFileData(headers, file));
     // the key is appending a file as opposed to just creating it - the original ms implementation is:
      // return File.Create(file, this.BufferSize, FileOptions.Asynchronous)
       return new FileStream(file, FileMode.Append, FileAccess.Write, FileShare.Write, this.BufferSize, true);}
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