How to get a file's Media Type (MIME type)?

Question

How do you get a Media Type (MIME type) from a file using Java? So far I've tried JMimeMagic & Mime-Util. The first gave me memory exceptions, the second doesn't close its streams properly.

How would you probe the file to determine its actual type (not merely based on the extension)?

Answer 1

In Java 7 you can now just use Files.probeContentType(path).

Answer 2

Unfortunately,

mimeType = file.toURL().openConnection().getContentType(); 

does not work, since this use of URL leaves a file locked, so that, for example, it is undeletable.

However, you have this:

mimeType= URLConnection.guessContentTypeFromName(file.getName()); 

and also the following, which has the advantage of going beyond mere use of file extension, and takes a peek at content

InputStream is = new BufferedInputStream(new FileInputStream(file)); mimeType = URLConnection.guessContentTypeFromStream(is);  //...close stream 

However, as suggested by the comment above, the built-in table of mime-types is quite limited, not including, for example, MSWord and PDF. So, if you want to generalize, you'll need to go beyond the built-in libraries, using, e.g., Mime-Util (which is a great library, using both file extension and content).