Java spring annotation service

Spring @Service Annotation with Example

Spring is one of the most popular Java EE frameworks. It is an open-source lightweight framework that allows Java EE 7 developers to build simple, reliable, and scalable enterprise applications. This framework mainly focuses on providing various ways to help you manage your business objects. It made the development of Web applications much easier than compared to classic Java frameworks and application programming interfaces (APIs), such as Java database connectivity (JDBC), JavaServer Pages(JSP), and Java Servlet. This framework uses various new techniques such as Aspect-Oriented Programming (AOP), Plain Old Java Object (POJO), and dependency injection (DI), to develop enterprise applications. Now talking about Spring Annotation

Spring Annotations are a form of metadata that provides data about a program. Annotations are used to provide supplemental information about a program. It does not have a direct effect on the operation of the code they annotate. It does not change the action of the compiled program.

There are many annotations are available in Spring Framework. Some of the Spring Framework Annotations are listed below as follows where here we are going to discuss one of the most important annotations that is @ServiceAnnotation

• @Required
• @Autowired
• @Configuration
• @ComponentScan
• @Bean
• @Component
• @Controller
• @Service
• @Repository, etc.

@Service Annotation

In an application, the business logic resides within the service layer so we use the @Service Annotation to indicate that a class belongs to that layer. It is also a specialization of @Component Annotation like the @Repository Annotation. One most important thing about the @Service Annotation is it can be applied only to classes. It is used to mark the class as a service provider. So overall @Service annotation is used with classes that provide some business functionalities. Spring context will autodetect these classes when annotation-based configuration and classpath scanning is used.

1. Create a Simple Spring Boot Project
2. Add the spring-context dependency in your pom.xml file.
3. Create one package and name the package as “service”.
4. Test the spring repository

Step 1: Create a Simple Spring Boot Project

Refer to this article Create and Setup Spring Boot Project in Eclipse IDE and create a simple spring boot project.

Step 2: Add the spring-context dependency in your pom.xml file. Go to the pom.xml file inside your project and add the following spring-context dependency.

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@Service Annotation in Spring

In this tutorial, you will learn what the @Service annotation is and how to use it in your Spring Boot applications.

@Service annotation is a part of the Spring Framework, and you will use it to mark a class as a service layer component. This annotation is typically used in conjunction with @Component, which is a general-purpose annotation for marking a class as a component in Spring.

To learn about other Spring Boot annotations, check out Spring Stereotype Annotations tutorial.

How to Use @Service Annotation

@Service annotation can be used to denote a class that performs a specific service or function in a Spring Boot application. You will use it to specify that a class performs business logic or data manipulation tasks.

To use @Service annotation in a Spring Boot Rest application with Maven, follow these steps:

Step 1. Add Spring Boot Web Dependency

Add the Spring Boot starter dependency in your pom.xml file:

 org.springframework.boot spring-boot-starter-web  

Step 2. Annotate Class with @Service Annotation

Create a class that performs a specific service or function in your application. For example, let’s say you want to create a class that sends notification messages. You can create a class called NotificationService:

@Service public class NotificationService < public void sendNotification(Notification notification) < // Code to send notification message >>

Step 3. Inject Service Class into a Controller Class

You can now use dependency injection and inject the NotificationService class into the component or controller that needs to use it. For example, if you want to use the NotificationService class in a controller, you can do the following:

@RestController public class NotificationsController < @Autowired private NotificationService notificationService; @PostMapping("/notifications/send") public void sendNotification(@RequestBody Notification notification) < notificationService.sendNotification(notification); >>

Now you can run your Spring Boot application and make a request to the /notifications/send endpoint to trigger the NotificationService’s sendNotification() method.

Frequently Asked Questions

1. What is the purpose of the @Service annotation?
   The primary purpose of the @Service annotation is to serve as a specialization of @Component. This lets the developer and other readers of the code understand that the class isn’t just any component, but a service with specific business logic.
2. How does the @Service annotation work with Spring’s dependency injection?
   When you mark a class with @Service, Spring will automatically register it as a single bean in the application context, which can be auto-wired into other beans as a dependency.
3. What’s the difference between @Service, @Repository, and @Controller in Spring?
   These are all stereotype annotations that mark classes as Spring components. They each serve different roles within the MVC pattern: @Repository classes interact with the database and handle data operations, @Service classes contain business logic, and @Controller classes handle incoming HTTP requests and return responses.
4. Can I use @Component instead of @Service? What’s the difference?
   Technically, you can use @Component instead of @Service, as both mark a class as a bean. However, using @Service provides additional semantic value by making it clear that the class is intended to hold business logic.
5. Do I need to use @Service annotation in Spring Boot?
   While not mandatory, using the @Service annotation is recommended in Spring Boot to take advantage of Spring’s automatic configuration and dependency injection features.
6. What is the scope of a @Service bean?
   By default, a @Service bean is a singleton, meaning Spring will create exactly one instance of the class and share it among all other beans. However, you can change this default scope using the @Scope annotation.

Conclusion

@Service annotation is a useful tool for organizing and separating business logic and data manipulation tasks in a Spring Boot application. By using @Service annotation, you can clearly denote which classes in your application are responsible for performing specific services and functions.

To learn more, check out Spring Boot tutorials page.

Related Posts:

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Spring @Service Annotation

While we believe that this content benefits our community, we have not yet thoroughly reviewed it. If you have any suggestions for improvements, please let us know by clicking the “report an issue“ button at the bottom of the tutorial.

Spring @Service annotation is a specialization of @Component annotation. Spring Service annotation can be applied only to classes. It is used to mark the class as a service provider.

Spring @Service Annotation

Spring @Service annotation is used with classes that provide some business functionalities. Spring context will autodetect these classes when annotation-based configuration and classpath scanning is used.

Spring @Service Example

Let’s create a simple spring application where we will create a Spring service class. Create a simple maven project in Eclipse and add following spring core dependency.

 org.springframework spring-context 5.0.6.RELEASE  

Our final project structure will look like below image. Let’s create a service class.

package com.journaldev.spring; import org.springframework.stereotype.Service; @Service("ms") public class MathService < public int add(int x, int y) < return x + y; >public int subtract(int x, int y) < return x - y; >> 

Notice that it’s a simple java class that provides functionalities to add and subtract two integers. So we can call it a service provider. We have annotated it with @Service annotation so that spring context can autodetect it and we can get its instance from the context. Let’s create a main class where we will create the annotation-driven spring context get the instance of our service class.

package com.journaldev.spring; import org.springframework.context.annotation.AnnotationConfigApplicationContext; public class SpringMainClass < public static void main(String[] args) < AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(); context.scan("com.journaldev.spring"); context.refresh(); MathService ms = context.getBean(MathService.class); int add = ms.add(1, 2); System.out.println("Addition of 1 and 2 = " + add); int subtract = ms.subtract(2, 1); System.out.println("Subtraction of 2 and 1 = " + subtract); //close the spring context context.close(); >> 

Jun 05, 2018 3:02:05 PM org.springframework.context.support.AbstractApplicationContext prepareRefresh INFO: Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@ff5b51f: startup date [Tue Jun 05 15:02:05 IST 2018]; root of context hierarchy Addition of 1 and 2 = 3 Subtraction of 2 and 1 = 1 Jun 05, 2018 3:02:05 PM org.springframework.context.support.AbstractApplicationContext doClose INFO: Closing org.springframework.context.annotation.AnnotationConfigApplicationContext@ff5b51f: startup date [Tue Jun 05 15:02:05 IST 2018]; root of context hierarchy 

If you notice our MathService class, we have defined the service name as “ms”. We can get the instance of MathService using this name too. The output will remain same in this case. However, we will have to use explicit casting.

MathService ms = (MathService) context.getBean("ms"); 

That’s all for a quick example of Spring @Service annotation. You can download the example project code from our GitHub Repository. Reference: API Doc

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