Dependency injection

DI is a system where dependencies of an object are provided by outside containers. Spring DI helps in wiring a class with its dependencies and keeping them decoupled so that we can inject these dependencies at runtime.

The dependencies are characterized in the bean configuration. The two most common approaches to injecting objects utilizing XML are constructor injection and setter injection, which we'll take a look at now:Constructor injection

Constructor injections inject dependencies to the class constructor. Let's take a look at an example of the constructor injection. Reuse the previous project and modify the content of beans.xml:

<?xml version = "1.0" encoding = "UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans" ...

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