Learn how the DI can be used to decouple the dependencies between different components.

Spring IoC

In Spring, the Inversion of Control (IoC) principle is implemented using the Dependency Injection (DI) design pattern. Let's understand dependency injection with the help of an example. First we will see a java version of the example and later we will add spring functionalities to it. As far as the example go, its pretty simple. The QuizMater interface exposes the popQuestion() method. To keep things simple, our QuizMaster will generate only one question.

Here a reference of SpringQuizMaster is injected to the QuizMaster bean. When we execute this example, "Are you new to Spring?" gets printed in the console.

To make our QuizMaster ask questions related to Struts, the only change we need to do is, to change the bean reference in the ref tag.