overview / mime-types

Java library to detect files' MIME types

MIME Type Detector

Ever see "application/octet-stream" or "text/plain" or "text/html"? Those are called MIME types. ("MIME" stands for Multi-purpose Internet Mail Extensions.)

If your Java program has files and needs to figure out their MIME types, this library will help.

Usage

import org.overviewproject.mime_types.MimeTypeDetector

// ...

File file = new File("foo.txt");
MimeTypeDetector detector = new MimeTypeDetector();
String mimeType = detector.detectMimeType(file); // "text/plain"

// ... or ...

InputStream stream = new ByteArrayInputStream("words".getBytes("utf-8"))
String mimeType = detector.detectMimeType("filename", stream); // "text/plain"

No library can figure out MIME types perfectly. But there's a standard, called shared-mime-info. This library follows its algorithm to the letter.

You need two things to detect a file's type:

1. The file's name
2. The first few bytes of the file's content

The bytes aren't always needed; for speed, you can pass a callback instead of the actual bytes, and this library will only invoke the callback when it's absolutely necessary. There's an async version, too.

For a method that matches the files you have, read the MimeTypeDetector docs.

Credits

Big thanks to Medsea Business Solutions S.L. for most of this code. I merely adjusted the API. (The original project at http://sourceforge.net/p/mime-util/ seems to be dead.)