How would you use constructor injection in Spring Framework

How would you use constructor injection in Spring Framework

How would you use constructor injection in Spring Framework?

Constructor injection in Spring Framework is used to inject dependencies into an object at the time of its creation. This method ensures that the object is never instantiated in an incomplete state.

To use constructor injection, you first define a bean in your XML configuration file or using annotations. The bean’s class should have a constructor that takes in all necessary dependencies as parameters.

For example:

public class MyClass {
    private MyDependency myDependency;
    public MyClass(MyDependency myDependency) {
        this.myDependency = myDependency;
    }
}
In the XML configuration file, you would then specify the dependency like so:

<bean id="myClass" class="com.example.MyClass">
    <constructor-arg ref="myDependency"/>
</bean>
<bean id="myDependency" class="com.example.MyDependency"/>
Or with annotations:

@Component
public class MyClass {
    private final MyDependency myDependency;
    @Autowired
    public MyClass(MyDependency myDependency) {
        this.myDependency = myDependency;
    }
}