Two approaches for loading cron expressions from a database in Spring Boot are compared. The first uses a Spring bean (cronLoader) referenced via SpEL in @Scheduled, which is simple but only reads the value once at startup. The second uses SchedulingConfigurer to register a trigger task that re-reads the cron expression from the database before each execution, enabling runtime schedule changes without restarting the application. An H2 in-memory database with JPA is used for demonstration, along with a REST endpoint to update the cron value on the fly.
Table of contents
1. Overview2. Introduction to the Problem3. Preparing Data in a Database4. Using a cronLoader Bean5. Using Spring’s SchedulingConfigurer6. ConclusionSort: