Assembling via Spring’s classpath scanning

If we use the Spring framework to assemble our application, the result is called the application context. The application context contains all objects that together make up the application (beans in Java lingo).

Spring offers several approaches to assemble an application context, each having its own advantages and drawbacks. Let’s start by discussing the most popular (and most convenient) approach: classpath scanning.

With classpath scanning, Spring goes through all classes that are available in a certain slice of the classpath and searches for classes that are annotated with the @Component annotation. The framework then creates an object from each of these classes. The classes should have a constructor that takes all required fields as an argument, like our AccountPersistenceAdapter from Chapter 7, Implementing a Persistence Adapter:

In this case, we didn’t even write the constructor ourselves...