稍微解释一下迪兰的回应:

有三个类实现了FileResult类:

System.Web.Mvc.FileResult
      System.Web.Mvc.FileContentResult
      System.Web.Mvc.FilePathResult
      System.Web.Mvc.FileStreamResult

它们都是不言自明的:

For file path downloads where the file exists on disk, use FilePathResult - this is the easiest way and avoids you having to use Streams. For byte[] arrays (akin to Response.BinaryWrite), use FileContentResult. For byte[] arrays where you want the file to download (content-disposition: attachment), use FileStreamResult in a similar way to below, but with a MemoryStream and using GetBuffer(). For Streams use FileStreamResult. It's called a FileStreamResult but it takes a Stream so I'd guess it works with a MemoryStream.

下面是一个使用内容处理技术的例子(未测试):

    [AcceptVerbs(HttpVerbs.Post)]
    public ActionResult GetFile()
    {
        // No need to dispose the stream, MVC does it for you
        string path = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "App_Data", "myimage.png");
        FileStream stream = new FileStream(path, FileMode.Open);
        FileStreamResult result = new FileStreamResult(stream, "image/png");
        result.FileDownloadName = "image.png";
        return result;
    }

你可以使用文件返回一个文件，如视图，内容等

 public ActionResult PrintDocInfo(string Attachment)
            {
                string test = Attachment;
                if (test != string.Empty || test != "" || test != null)
                {
                    string filename = Attachment.Split('\\').Last();
                    string filepath = Attachment;
                    byte[] filedata = System.IO.File.ReadAllBytes(Attachment);
                    string contentType = MimeMapping.GetMimeMapping(Attachment);

                    System.Net.Mime.ContentDisposition cd = new System.Net.Mime.ContentDisposition
                    {
                        FileName = filename,
                        Inline = true,
                    };

                    Response.AppendHeader("Content-Disposition", cd.ToString());

                    return File(filedata, contentType);          
                }
                else { return Content("<h3> Patient Clinical Document Not Uploaded</h3>"); }

            }

为什么不简单一点，使用波浪号~操作符呢?

public FileResult TopBanner() {
  return File("~/Content/images/topbanner.png", "image/png");
}

使用基本控制器文件方法。

public ActionResult Image(string id)
{
    var dir = Server.MapPath("/Images");
    var path = Path.Combine(dir, id + ".jpg"); //validate the path for security or use other means to generate the path.
    return base.File(path, "image/jpeg");
}

值得一提的是，这似乎相当有效。我做了一个测试，我通过控制器(http://localhost/MyController/Image/MyImage)和直接URL (http://localhost/Images/MyImage.jpg)请求图像，结果是:

MVC:每张照片7.6毫秒 直接:每张照片6.7毫秒

注意:这是一个请求的平均时间。平均值是通过在本地机器上发出数千个请求来计算的，因此总数不应该包括网络延迟或带宽问题。

稍微解释一下迪兰的回应:

有三个类实现了FileResult类:

System.Web.Mvc.FileResult
      System.Web.Mvc.FileContentResult
      System.Web.Mvc.FilePathResult
      System.Web.Mvc.FileStreamResult

它们都是不言自明的:

For file path downloads where the file exists on disk, use FilePathResult - this is the easiest way and avoids you having to use Streams. For byte[] arrays (akin to Response.BinaryWrite), use FileContentResult. For byte[] arrays where you want the file to download (content-disposition: attachment), use FileStreamResult in a similar way to below, but with a MemoryStream and using GetBuffer(). For Streams use FileStreamResult. It's called a FileStreamResult but it takes a Stream so I'd guess it works with a MemoryStream.

下面是一个使用内容处理技术的例子(未测试):

    [AcceptVerbs(HttpVerbs.Post)]
    public ActionResult GetFile()
    {
        // No need to dispose the stream, MVC does it for you
        string path = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "App_Data", "myimage.png");
        FileStream stream = new FileStream(path, FileMode.Open);
        FileStreamResult result = new FileStreamResult(stream, "image/png");
        result.FileDownloadName = "image.png";
        return result;
    }

您可以直接写入响应，但这样它就不可测试了。最好返回一个延迟执行的ActionResult。这是我的可重用StreamResult:

public class StreamResult : ViewResult
{
    public Stream Stream { get; set; }
    public string ContentType { get; set; }
    public string ETag { get; set; }

    public override void ExecuteResult(ControllerContext context)
    {
        context.HttpContext.Response.ContentType = ContentType;
        if (ETag != null) context.HttpContext.Response.AddHeader("ETag", ETag);
        const int size = 4096;
        byte[] bytes = new byte[size];
        int numBytes;
        while ((numBytes = Stream.Read(bytes, 0, size)) > 0)
            context.HttpContext.Response.OutputStream.Write(bytes, 0, numBytes);
    }
}