如何查看上传的文件是否为XLS文件？

Question

I have a file uploader module. The UI is created using simple HTML and Javascript. Server side I am using Java code. I want to check the type of the uploaded file.

Answer 1

Files don't really have types. The best you can do would be to attempt to load the file as an XLS.

• If the load succeeds, the file is most likely an XLS.
• If the load fails, the file is either an invalid/malformed XLS, or not an XLS at all.

You can also look at the uploaded file name or the content type, but neither of these is definitive; ie they might say that the file is an XLS when it is something completely different.