I am searching for a java library which tells you the mime type by looking at the file content(byte array). I found this project using jmimemagic and it no longer supports newer file types (eg. MS word docx format) as it is inactive now (from 2006).
Use Apache tika for content detection. Please find the link below. http://tika.apache.org/0.8/detection.html. We have so many jar dependencies which you can find when you build tika using maven
ByteArrayInputStream bai = new ByteArrayInputStream(pByte);
ContentHandler contenthandler = new BodyContentHandler();
Metadata metadata = new Metadata();
Parser parser = new AutoDetectParser();
try {
parser.parse(bai, contenthandler, metadata);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SAXException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (TikaException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println("Mime: " + metadata.get(Metadata.CONTENT_TYPE));
return metadata.get(Metadata.CONTENT_TYPE);