How to manage JARs with third-party implementations in configuration classes?

Question

Assume that

• I like to manage the configuration of a Java application in form of one or many classes referencing each other which I de/serialize to/from XML because I like the way how that saves a lot of work.
• I have a Java project with interfaces and the application packaged in different JARs where interfaces are designed to allow third-parties to implement interfaces and the user to load them at runtime through a fancy GUI. Configuration classes exist in form of interfaces and thus can occur in the serialized XML.
• I would like to have one configuration file only controlling all pathes of all resources (I'll probably have to give that up, but I'm curious about your answers). It is searched for in a default location and created with default values if inexisting or can be specified on command line.

How would I go about getting the information about the location of third-party implementations before loading the configuration and still keep one clean configuration file only?

Answer 1

I

• parse the XML once using XStream and XStream.omitField for the field which contains instances of configuration classes which need to be loaded from a referenced JAR.
• Then I read the partial configuration to the location of the JARs and load the classes.
• Then I overwrite the partially parsed configuration with a completely deserialized one (using a new instance of XStream ).