What is the underlying principle of quartz?

Quartz is an open-source job scheduling framework used to execute scheduled tasks in Java applications. Its underlying principles mainly include the following aspects:

1. Scheduler: Quartz uses a scheduler to manage and execute jobs. The scheduler is responsible for triggering the execution of jobs according to a predetermined schedule.
2. Homework: Homework is an abstract representation of tasks or actions to be carried out. In Quartz, homework is represented by classes that implement the Job interface. Homework can be triggered for execution by the scheduler.
3. Trigger: A trigger is used to specify the execution time of a job. It defines when a job should be executed and how it should be repeated. In Quartz, there are various types of triggers to choose from, such as simple triggers and Cron triggers.
4. Storage: Quartz supports storing configuration information for jobs and triggers in a database so that the scheduling state can be restored when the application restarts.
5. Listeners: Quartz provides a set of listener mechanisms to monitor and respond to the execution events of jobs. Developers can customize listeners to handle events before, during, and after job execution.

In general, the underlying principle of Quartz is to schedule and execute timed tasks through the collaboration of a scheduler, job, trigger, and storage.