In this tutorial, we are going to learn about stereotype annotations in the spring framework.
@Component, @Service, @Repository, @Controller are considered to be the stereotype annotations in spring.
You can also find the advantages of the Spring framework along with this tutorial so that you can have a better understanding of the spring framework.
Here is the list of spring core stereotype annotations:
Stereotype annotations in Spring:
Stereotype annotations were introduced in the spring 2.0 with a single type called @Repository. In Spring 2.5 spring introduced a generic stereotype annotation called @Component, this is an extension of spring 2.0 stereotype annotations with different component types.
As we all know that, a component is a generic term. We can term anything as a component. So that the spring also followed the same rule, that’s why the @Component annotation is defined as a generic/super. The @Service, @Repository, @Controller are the annotation are the sub/concrete types of @Component.
Spring core annotation @Component
@Component is a generic stereotype annotation, it can be used on top of a class. If we declare a @Component on top of a class, then that class will be automatically configured by the Spring IOC container, with the unqualified class name as id like below.
Example:
package com.onlinetutorialspoint.beans;
import org.springframework.stereotype.Component;
@Component
public class DemoBean {
}Spring IOC container will automatically configure the above DemoBean class with id demoBean.
In order to tell the spring container that scan for the components (beans) in a package or its sub-packages, we have to configure the component scan in spring configuration XML like below.
<context:component-scan base-package="com.onlinetutorialspoint.beans" />We can also define the multiple base packages in component-scan like below:
<context:component-scan base-package="com.onlinetutorialspoint.beans, com.onlinetutorialspoint.controllers" />In order to tell the Spring IOC container to process the annotations, we need to configure the information in the spring configuration file like below.
<context:annotation-config />Spring Core annotation @Service :
@Service is a sub-annotation of the @Component annotation. We can define the @Service annotation on top of a class. In order to indicate a class that comes under the business layer, we can define those classes with @Service annotation.
package com.onlinetutorialspoint.beans;
import org.springframework.stereotype.Service;
@Service
public class ProductService {
}If we declare @Service annotation on top of a class, then it will automatically be configured by IOC container, because @Service annotation is a sub-annotation of @Component annotation.
Spring Core annotation @Repository :
We can define the @Repository annotation on top of a class. In order to indicate a class that comes under the persistent layer, we can define those classes with @Repository annotation. @Repository is a sub-annotation of the @Component.
package com.onlinetutorialspoint.beans;
import org.springframework.stereotype.Repository;
@Repository
public class ProductDAOImpl {
}Spring Core annotation @Controller :
We can define the @Controller annotation on top of a class. In order to indicate a class that comes under the presentation layer, we can define those class with @Controller annotation.
package com.onlinetutorialspoint.controllers;
import org.springframework.stereotype.Controller;
@Controller
public class ProductController {
}@Controller is a sub-annotation of the @Component annotation, hence it will automatically configure by the Spring IOC container.
References:
Happy Learning 🙂
