正在使用AngularJS将文件发布到WebApi2 -无法获取文件名或标头

var formData = new FormData();
formData.append('file', file, file.name);
$http.post('/api/upload', formData, {
    transformRequest: angular.identity,
    headers: {'Content-Type': undefined}
}).then(function(response) {
    // 处理上传成功后的逻辑
}, function(error) {
    // 处理上传失败后的逻辑
});

public async Task<HttpResponseMessage> Upload()
{
    if (!Request.Content.IsMimeMultipartContent())
    {
        throw new HttpResponseException(HttpStatusCode.UnsupportedMediaType);
    }

    var provider = new MultipartFormDataStreamProvider("uploadDirectory");
    await Request.Content.ReadAsMultipartAsync(provider);

    // 获取文件名
    string fileName = provider.FileData[0].Headers.ContentDisposition.FileName;

    // 获取标头
    string header = provider.FileData[0].Headers.GetValues("HeaderName").FirstOrDefault();

    // 处理上传的文件
    // ...

    return Request.CreateResponse(HttpStatusCode.OK);
}