How do I encode a file name for download?

问题:

When the file name is "Algunas MARCAS que nos acompañan" ASP.NET MVC raise an System.FormatException when I try to download that file. But if the file name is "Asistente de Gerencia Comercial" it doesn't.

I guess this is because something related to UTF-8 encoding, but I don't know how to encode that string.

If I'm right, how can I encode the string in UTF-8 encoding? If I'm not right, what is my problem?

回答1:

I encode file name like this for downloading,

HttpContext.Current.Response.AppendHeader("Content-Disposition", "attachment;filename= " + HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8));

回答2:

Based on ZZ Coder answer, and because I'm using FileResult, I decided to encode the file name as:

HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8)

回答3:

This issue has been known for years. As far as I can tell, there currently is no interoperable way to do this, so the answer is to only support one set of browsers, or to do User Agent sniffing.

Test cases and links at: http://greenbytes.de/tech/tc2231/

回答4:

I recently fought with this a bit, having many potential languages being used for the file names (Chinese is good to test with). Here is something close to what I ended up with (other implementation details excluded):

HttpUtility.UrlEncode("é", System.Text.Encoding.GetEncoding("ISO-8859-1"))

回答5:

Also: HttpUtility considered harmful:
http://serialseb.blogspot.com/2008/03/httputilityurlencode-considered-harmful.html

I'm just going to punt and replace " " with "_" and call it a day =)

回答6:

note that using UTF encoding replaces the spaces in the file name into '+', using either the following codes produce the same results:

HttpUtility.UrlEncode("é", System.Text.Encoding.GetEncoding("ISO-8859-1"))
HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8)

回答7:

instead of using httpUtility that replaces the spaces in the file name with "+" using the following code resolve the problem:

string attachment = String.Format("attachment; filename={0}",Server.UrlPathEncode(file.Name.TrimEnd()));
Response.AddHeader("Content-Disposition", attachment);

please note that if you retrieve file name from data set you may need trim the name first! you have to also add the following lines of code in advance:

Response.Charset = "utf-8";
Response.HeaderEncoding = UnicodeEncoding.UTF8;
Response.ContentEncoding = UnicodeEncoding.UTF8;