一个文件下载接口引发的血案Content-Disposition之殇

今天在迁移一个老系统到新服务器的时候，在测试下载接口的时候发现：同一个接口，有些文件可以下载，有些文件不能下载。

调试了半天发现，好像是文件名的问题。

string fileName = "38374-fjf(1).13jk";
string contentDisposition = string.Format("attachment;filename={0}",fileName);
msg.Content.Headers.ContentDisposition = ContentDispositionHeaderValue.Parse(contentDisposition);

于是乎悲剧了。

然后我百度了一下，网上似乎都是什么书说文件名乱码的，没有一个说说是我这种清空情况。

无奈去查了一下标准文档 http://www.ietf.org/rfc/rfc6266.txt

跳过前面的定义直接看例子

5.  Examples

   Direct the UA to show "save as" dialog, with a filename of
   "example.html":

     Content-Disposition: Attachment; filename=example.html

   Direct the UA to behave as if the Content-Disposition header field
   wasn‘t present, but to remember the filename "an example.html" for a
   subsequent save operation:

     Content-Disposition: INLINE; FILENAME= "an example.html"

   Note: This uses the quoted-string form so that the space character
   can be included.

   Direct the UA to show "save as" dialog, with a filename containing
   the Unicode character U+20AC (EURO SIGN):

     Content-Disposition: attachment;
                          filename*= UTF-8‘‘%e2%82%ac%20rates

   Here, the encoding defined in [RFC5987] is also used to encode the
   non-ISO-8859-1 character.

   This example is the same as the one above, but adding the "filename"
   parameter for compatibility with user agents not implementing
   RFC 5987:

     Content-Disposition: attachment;
                          filename="EURO rates";
                          filename*=utf-8‘‘%e2%82%ac%20rates

   Note: Those user agents that do not support the RFC 5987 encoding
   ignore "filename*" when it occurs after "filename".

　　Note: This uses the quoted-string form so that the space character
   can be included.

看到这句我似乎发现了什么。如果有空格就需要写成字符串引用的格式。

string contentDisposition = string.Format("attachment;filename=\"{0}\"", fileName);

文件名有特殊符号是解决了，比如括号，空格什么的。但是如果文件名当中有中午，下载时候的默认文件名缺还是乱码。

这个网上有一堆解决方案。

string fileName= HttpUtility.UrlEncode("啊fnam(4)e.ext",UTF8Encoding.UTF8);

其实只要对文件名做一次Encode转码就行了。

就这个简单的问题，耗费了我一个小时。

今天就先到这里，晚安。