How can I get the actual file extension in Java

Question

I know I can get this by doing this

String ext = FilenameUtils.getExtension("/path/to/file/foo.txt");

But what if someone tries to upload a foo.exe file by just changing the extension type to foo.doc. Is there any way through which I can get the actual extension type without reading the content of file

MIME types, magic number headers, etc. – Mena Oct 09 '15 at 13:11 — Mena, Oct 09 '15 at 13:11

score 2 · Answer 1 · edited May 23 '17 at 12:06

2

File file = new File("filename.asgdsag");
InputStream is = new BufferedInputStream(new FileInputStream(file));
String mimeType = URLConnection.guessContentTypeFromStream(is);

From this post : Get real file extension -Java code

Also using java7, you should check out this :

public static String probeContentType(Path path)
                           throws IOException

http://docs.oracle.com/javase/7/docs/api/java/nio/file/Files.html#probeContentType%28java.nio.file.Path%29

edited May 23 '17 at 12:06

Community

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answered Oct 09 '15 at 13:12

Alexandre Beaudet

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Thanks Alexandre, let me try this. I tried to find it on stackoverflow, But didn't found that – Vipul Jain Oct 09 '15 at 13:14
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Do not post the code from the duplicate, instead, mark the post as duplicate and link to the duplicated item. – KevinDTimm Oct 09 '15 at 13:14
Alright Kevin, my bad, kinda new around here – Alexandre Beaudet Oct 09 '15 at 13:15
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Note you're not getting downvotes - only because you're new :) – KevinDTimm Oct 09 '15 at 13:16
I tried this but I got mimeType as null in that case. I am using mulipartFile. – Vipul Jain Oct 09 '15 at 13:54
And also I tried ProbeContentType, but it is only giving me the real type of extension. Is there any way ?? – Vipul Jain Oct 09 '15 at 14:08

How can I get the actual file extension in Java

1 Answers1