What is @Service In Spring?

This is a class-level annotation that is a specialization of @Component designed to handle business logic. It will turn your class into a Spring-managed bean.

Why is it important?

By using this annotation, you are implementing a separation of concerns by placing the business logic in a specific layer, thereby improving code readability.

How to use it?

First, define a class annotated with @Service that has some business logic in the methods:

package com.example.demo.service;

import org.springframework.stereotype.Service;

@Service
public class UserService {

    public String getWelcomeMessage(String username) {
        return "Welcome, " + username + "!";
    }
}

Then inject your created service where it’s needed:

package com.example.demo.controller;

import com.example.demo.service.UserService;
import org.springframework.web.bind.annotation.*;

@RestController
@RequestMapping("/users")
public class UserController {

    private final UserService userService;

    public UserController(UserService userService) {
        this.userService = userService;
    }

    @GetMapping("/{username}")
    public String welcomeUser(@PathVariable String username) {
        return userService.getWelcomeMessage(username);
    }
}

Let’s test it

Let’s call our endpoint

curl http://localhost:8080/users/SpringMastery

The result should look like this:

Welcome, SpringMastery!

Conclusion

That’s it, it's that easy to create a service in your application. Now you know how, when to use, and how important this annotation is in your Spring applications.

Have you ever thought about the difference between @Service and @Component?