Dependency injection in Spring

Because DI is at the core of the Spring Framework, let's spend some time understanding how it works in Spring. We will create a standalone application for this purpose. Create a simple Maven project. Add the following dependency for the Spring Framework:

    <dependency> 
      <groupId>org.springframework</groupId> 
      <artifactId>spring-context</artifactId> 
      <version>5.0.5.RELEASE</version> 
    </dependency> 

Replace the preceding version number with the latest version of Spring. Classes managed by the DI container of Spring are called beans or components. You can either declare beans in an XML file or you can annotate the class. We will use annotations in this chapter. However, even though we use annotations, we need to specify the minimum configuration in an XML file. So, create an...