When a trigger fires, the job it is associated with is instantiated via the JobFactory configured on the Scheduler. The default JobFactory simply calls newInstance() on the job class. You may want to create your own implementation of JobFactory to accomplish things such as having your application's IoC or DI container produce/initialize the job instance.

See the org.quartz.spi.JobFactory interface, and the associated Scheduler.setJobFactory(fact) method.