User preferences in JEE application

Question

I have a growing web application which now needs to be able to store user and system preferences / settings. In the past I've always rolled my own preferences system for web applications but I was wondering what other people do to solve this problem? Are there any preference libraries for web applications that people could recommend?

Ideally user preferences should have a default value which the user can then override. Not all preferences should be exposed to the user though as some will be for things such as the last position of a dialog box.

If I go the roll-my-own route I think it will be a separate preferences table with all the preferences stored as strings converted to their true, primitive, data type as required. e.g. a table something like key,user_key,setting_name,setting_value. I favour this approach to a column per data type because it stops a setting from accidently ending up with two values and the consumer of a setting should know what data type they want.

Answer 1

One approach we use is:

• all non-mandatory properties have defaults in code
• deliver a properties file with the web application in which we define the technical oriented properties
• query a SQL table on application startup to load mainly functional oriented properties

The properties from the database have a higher priority than those from the included property file. If your requirement is to prevent functional managers from changing techical properties you can add a context column to the properties table which is checked in the management UI.

All the application code gets to see is one globally used properties collection.

Answer 2

There's a JDK API for that: java.util.prefs

http://java.sun.com/j2se/1.4.2/docs/guide/lang/preferences.html