Why I like Spring bean aliasing

Spring framework is widely used as a dependency injection container, and that’s for good reasons. First of all, it facilitates integration testing and it gives us the power of customizing bean creation and initialization (e.g. @Autowired for List types).

But there is also a very useful feature, that might get overlooked and therefore let’s discuss about bean aliasing.

Bean aliasing allows us to override already configured beans and to substitute them with a different object definition. This is most useful when the bean definitions are inherited from an external resource, which is out of our control.

In the following example, I will show you how bean aliasing works. Let’s start with the following bean definition, coming from the src/main/resources/spring/applicationContext-tx.xml configuration file.

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Why I like Spring @Autowired for List types

Spring Framework dependency injection is great, and almost every Java developer uses it nowadays. Using @Autowired to inject Java Beans is trivial, but we can also use this annotation for java.util.List, or java.util.Map as well. The former will inject a list of all Java Beans matching the List’s Generic type, while the latter will create a map of these beans mapped by their names.

How I’ve been taking advantage of this feature?

Since I was developing an application which has a framework module and a specific customer implementation module, there were cases where I needed to add a common logic in the framework module which would detect all Beans of a given type, even the ones defined in the specific module.

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