C＃-字节数组和文件扩展名

Question

I have a byte array that I've downloaded which lacks a file extension. I need to give this file an extension, which in my case will always be .gif, and convert back to a byte array.

I'm accomplishing the first step thus:

FileContentResult file = File(imageList.Single(), "image/gif");

I'm not sure what to do next. FileContentResult has a FileContents parameter which is of type byte array. I've tried using that, but it doesn't appear to contain the extension in the data.

Do byte arrays even contain the extension type? This is my first time working with one, so my understanding of what they are and what I can do with them is lacking.

Answer 1

image/gif is a mime type used on the internet to tell the client how to interpret a set of data.

It is not required if you save the data to disk.

Answer 2

I think maybe your wording of the problem domain is a little misleading. When you use the term "downloaded", do you mean "retrieved by way of an http connection", or "read (past tense) from a disk file, or a database field"??

I'm thinking it's the latter case -- so I'll proceed.

Raw data, when pulled in this way, will NOT have a filename. Why??? A filename is a pointer to some data within a file system. If you have a brown paper bags marked "green things", and you happen to pull an apple out of the bag, there's intrinsically within that apple to associate that apple (raw data) with the bag marked "green things" (the pointer).

Since your code makes reference to a FileContentResult, I infer that you are using MVC, and that you are within controller code, trying to deliver the byte array back to a browser.

If you take a peek at the link below here, you might find that the FileContentResult object has a neat property called "FileDownloadName". This is where you want to set the name of the file - append the extension.

http://msdn.microsoft.com/en-us/library/system.web.mvc.filecontentresult(v=vs.118).aspx