我使用以下类来获得更多带有 content-disposition 标头的选项。
它的工作原理与Marnix answer 非常相似，但它没有使用ContentDisposition 类完全生成标头，不幸的是，当文件名必须为utf-8 编码时，它不符合RFC，而是调整了标头由 MVC 生成，符合 RFC。
（最初，我部分地使用this response to another question 和这个another one 来编写。）
using System;
using System.IO;
using System.Web;
using System.Web.Mvc;
namespace Whatever
{
/// <summary>
/// Add to FilePathResult some properties for specifying file name without forcing a download and specifying size.
/// And add a workaround for allowing error cases to still display error page.
/// </summary>
public class FilePathResultEx : FilePathResult
{
/// <summary>
/// In case a file name has been supplied, control whether it should be opened inline or downloaded.
/// </summary>
/// <remarks>If <c>FileDownloadName</c> is <c>null</c> or empty, this property has no effect (due to current implementation).</remarks>
public bool Inline { get; set; }
/// <summary>
/// Whether file size should be indicated or not.
/// </summary>
/// <remarks>If <c>FileDownloadName</c> is <c>null</c> or empty, this property has no effect (due to current implementation).</remarks>
public bool IncludeSize { get; set; }
public FilePathResultEx(string fileName, string contentType) : base(fileName, contentType) { }
public override void ExecuteResult(ControllerContext context)
{
FileResultUtils.ExecuteResultWithHeadersRestoredOnFailure(context, base.ExecuteResult);
}
protected override void WriteFile(HttpResponseBase response)
{
if (Inline)
FileResultUtils.TweakDispositionAsInline(response);
// File.Exists is more robust than testing through FileInfo, especially in case of invalid path: it does yield false rather than an exception.
// We wish not to crash here, in order to let FilePathResult crash in its usual way.
if (IncludeSize && File.Exists(FileName))
{
var fileInfo = new FileInfo(FileName);
FileResultUtils.TweakDispositionSize(response, fileInfo.Length);
}
base.WriteFile(response);
}
}
/// <summary>
/// Add to FileStreamResult some properties for specifying file name without forcing a download and specifying size.
/// And add a workaround for allowing error cases to still display error page.
/// </summary>
public class FileStreamResultEx : FileStreamResult
{
/// <summary>
/// In case a file name has been supplied, control whether it should be opened inline or downloaded.
/// </summary>
/// <remarks>If <c>FileDownloadName</c> is <c>null</c> or empty, this property has no effect (due to current implementation).</remarks>
public bool Inline { get; set; }
/// <summary>
/// If greater than <c>0</c>, the content size to include in content-disposition header.
/// </summary>
/// <remarks>If <c>FileDownloadName</c> is <c>null</c> or empty, this property has no effect (due to current implementation).</remarks>
public long Size { get; set; }
public FileStreamResultEx(Stream fileStream, string contentType) : base(fileStream, contentType) { }
public override void ExecuteResult(ControllerContext context)
{
FileResultUtils.ExecuteResultWithHeadersRestoredOnFailure(context, base.ExecuteResult);
}
protected override void WriteFile(HttpResponseBase response)
{
if (Inline)
FileResultUtils.TweakDispositionAsInline(response);
FileResultUtils.TweakDispositionSize(response, Size);
base.WriteFile(response);
}
}
/// <summary>
/// Add to FileContentResult some properties for specifying file name without forcing a download and specifying size.
/// And add a workaround for allowing error cases to still display error page.
/// </summary>
public class FileContentResultEx : FileContentResult
{
/// <summary>
/// In case a file name has been supplied, control whether it should be opened inline or downloaded.
/// </summary>
/// <remarks>If <c>FileDownloadName</c> is <c>null</c> or empty, this property has no effect (due to current implementation).</remarks>
public bool Inline { get; set; }
/// <summary>
/// Whether file size should be indicated or not.
/// </summary>
/// <remarks>If <c>FileDownloadName</c> is <c>null</c> or empty, this property has no effect (due to current implementation).</remarks>
public bool IncludeSize { get; set; }
public FileContentResultEx(byte[] fileContents, string contentType) : base(fileContents, contentType) { }
public override void ExecuteResult(ControllerContext context)
{
FileResultUtils.ExecuteResultWithHeadersRestoredOnFailure(context, base.ExecuteResult);
}
protected override void WriteFile(HttpResponseBase response)
{
if (Inline)
FileResultUtils.TweakDispositionAsInline(response);
if (IncludeSize)
FileResultUtils.TweakDispositionSize(response, FileContents.LongLength);
base.WriteFile(response);
}
}
public static class FileResultUtils
{
public static void ExecuteResultWithHeadersRestoredOnFailure(ControllerContext context, Action<ControllerContext> executeResult)
{
if (context == null)
throw new ArgumentNullException("context");
if (executeResult == null)
throw new ArgumentNullException("executeResult");
var response = context.HttpContext.Response;
var previousContentType = response.ContentType;
try
{
executeResult(context);
}
catch
{
if (response.HeadersWritten)
throw;
// Error logic will usually output a content corresponding to original content type. Restore it if response can still be rewritten.
// (Error logic should ensure headers positionning itself indeed... But this is not the case at least with HandleErrorAttribute.)
response.ContentType = previousContentType;
// If a content-disposition header have been set (through DownloadFilename), it must be removed too.
response.Headers.Remove(ContentDispositionHeader);
throw;
}
}
private const string ContentDispositionHeader = "Content-Disposition";
// Unfortunately, the content disposition generation logic is hidden in an Mvc.Net internal class, while not trivial (UTF-8 support).
// Hacking it after its generation.
// Beware, do not try using System.Net.Mime.ContentDisposition instead, it does not conform to the RFC. It does some base64 UTF-8
// encoding while it should append '*' to parameter name and use RFC 5987 encoding. https://www.rfc-editor.org/rfc/rfc6266#section-4.3
// And https://stackoverflow.com/a/22221217/1178314 comment.
// To ask for a fix: https://github.com/aspnet/Mvc
// Other class : System.Net.Http.Headers.ContentDispositionHeaderValue looks better. But requires to detect if the filename needs encoding
// and if yes, use the 'Star' suffixed property along with setting the sanitized name in non Star property.
// MVC 6 relies on ASP.NET 5 https://github.com/aspnet/HttpAbstractions which provide a forked version of previous class, with a method
// for handling that: https://github.com/aspnet/HttpAbstractions/blob/dev/src/Microsoft.Net.Http.Headers/ContentDispositionHeaderValue.cs
// MVC 6 stil does not give control on FileResult content-disposition header.
public static void TweakDispositionAsInline(HttpResponseBase response)
{
var disposition = response.Headers[ContentDispositionHeader];
const string downloadModeToken = "attachment;";
if (string.IsNullOrEmpty(disposition) || !disposition.StartsWith(downloadModeToken, StringComparison.OrdinalIgnoreCase))
return;
response.Headers.Remove(ContentDispositionHeader);
response.Headers.Add(ContentDispositionHeader, "inline;" + disposition.Substring(downloadModeToken.Length));
}
public static void TweakDispositionSize(HttpResponseBase response, long size)
{
if (size <= 0)
return;
var disposition = response.Headers[ContentDispositionHeader];
const string sizeToken = "size=";
// Due to current ancestor semantics (no file => inline, file name => download), handling lack of ancestor content-disposition
// is non trivial. In this case, the content is by default inline, while the Inline property is <c>false</c> by default.
// This could lead to an unexpected behavior change. So currently not handled.
if (string.IsNullOrEmpty(disposition) || disposition.Contains(sizeToken))
return;
response.Headers.Remove(ContentDispositionHeader);
response.Headers.Add(ContentDispositionHeader, disposition + "; " + sizeToken + size.ToString());
}
}
}
示例用法：
public FileResult Download(int id)
{
// some code to get filepath and filename for browser
...
return
new FilePathResultEx(filepath, System.Web.MimeMapping.GetMimeMapping(filename))
{
FileDownloadName = filename,
Inline = true
};
}
请注意，使用Inline 指定文件名将不适用于 Internet Explorer（包括 11，包括 Windows 10 Edge，已使用一些 pdf 文件进行测试），但它适用于 Firefox 和 Chrome。 Internet Explorer 将忽略文件名。对于 Internet Explorer，您需要破解您的 url 路径，这在 imo 中是相当糟糕的。见this answer。