I use javax.activation.MimetypesFileTypeMap. It starts with a small set: $JRE_HOME/lib/content-types.properties, but you can add you own. Create a file mime.types in the format shown in MimetypesFileTypeMap's javadoc (I started with a large list from the net, massaged it, and added types I found missing). Now you can add that in your code by opening your mime.types file and adding its contents to your map. However the easier solution is to add your mime.types file to the META-INF of your jar. java.activation will pick that up automagically.
