What design patterns are implemented in the Spring Framework?

The Spring Framework implements many design patterns that help create flexible and maintainable applications:

• Dependency Injection — the core pattern that manages object dependencies through the Spring container.

• Singleton — Spring by default creates beans as singletons, ensuring a single instance per container.

• Factory Method — used for creating beans via configuration classes or XML, where factory methods instantiate objects.

• Proxy — applied in aspects (AOP) to add additional behavior (e.g., logging, transactions) without modifying the original code.

• Template Method — implemented in classes like JdbcTemplate, RestTemplate, where the overall execution algorithm is defined, and details can be overridden.

• Observer — through Spring ApplicationEvent and listeners, it is possible to implement event-driven reactions.

• Builder — often used in configuration and creation of complex objects via the "builder" pattern.

These patterns make Spring a powerful and flexible tool for enterprise application development.