Dependency Injection in Spring Boot

 Dependency Injection in Spring Boot


 
Dependency Injection in Spring Boot




What is Dependency Injection?
Injecting dependency to the class from outside (External service - Spring Container).


Why Dependency Injection?
We want to achieve loose coupling.

How we will do Dependency injection in Spring and Spring boot?
Spring: we will create an external XML file (let's say bean.xml) and from XML we will inject dependencies.

Spring Boot: write the annotation @Component above the dependent class by writing @component above any class we are making that class component of spring framework, the class which wants the object of the dependent class has to mention @Autowired above the object reference.

Ex.
@Components
class HitachiHD implements HardDrive{............}

class Laptop{
@Autowired
HardDrive obj;
}

ScreenShot
Car Interface

STS









Alto car as Spring Component

STS2














Autowire with Spring IoC

STS Autowire












Benefits of Dependency injection:

1. Loose coupling
2. Easy unit testing

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