Just Spring

Chapter 2. Fundamentals

We saw the bare-minimum basics of Spring Framework in the last chapter. We worked with new things such as beans, bean factories, and containers. This chapter explains them in detail. It discusses writing beans, naming conventions, how they are wired into containers, and so on.

Configuring Beans

For Spring, all objects are beans! The fundamental step in the Spring Framework is to define your objects as beans. Beans are nothing but object instances that would be created and manage by the Spring Framework by looking at their class definitions. These definitions basically form the configuration metadata. The framework then creates a plan for which objects need to be instantiated, which dependencies need to be set and injected, and the scope of the newly created instance, etc., is based on this configuration metadata.

The metadata can be supplied in a simple XML file, as we saw in Chapter 1. Alternatively, one could provide the metadata as annotation or Java Configuration.

We first discover the definitions of the Spring beans by using a config file which is discussed in the next section.

Using XML

We saw earlier that the Framework reads the Java classes defined in the XML config and initializes and loads them as Spring beans into a runtime container. The container is a runtime bucket of all the fully prepared instances of Java classes. Let’s take a look at an example of how this process is executed.

We will define a bean with a name person that corresponds to a class ...