Dependency Injection in Spring Framework

Dependency Injection is a design pattern in which objects are passed their dependencies rather than creating them internally. In the context of the Spring framework, dependency injection is implemented to manage and inject object dependencies automatically.

Implementation in Spring Framework

In Spring, dependency injection is mainly achieved through two ways:

1. Constructor Injection: Dependencies are injected through a class constructor. This is a recommended way as it ensures object immutability and helps maintain a clear contract for the class.
2. Setter Injection: Dependencies are injected using setter methods. While setter injection provides flexibility in changing dependencies at runtime, it may lead to mutable objects.

Spring framework provides various ways to configure dependency injection:

• XML-based configuration
• Annotation-based configuration
• Java-based configuration

By using these configuration options, developers can define dependencies and the Spring container manages the injection of these dependencies into the objects at runtime, promoting loose coupling and easier unit testing.

Understanding and implementing dependency injection in the Spring framework is crucial for building maintainable, testable, and flexible applications.