Spring Boot Annotations Cheat Sheet — Ultimate Reference for Java Developers

by Apu Das Gupta

Introduction

Spring Boot simplifies Java development by reducing boilerplate and providing powerful annotations. This cheat sheet is a quick reference to the most essential Spring Boot annotations that every developer should know — perfect for daily use and interview prep.

Core Spring Boot Annotations

@SpringBootApplication

Marks the main class of a Spring Boot application. Combines @Configuration, @EnableAutoConfiguration, and @ComponentScan.

@SpringBootApplication
public class MyApp {
    public static void main(String[] args) {
        SpringApplication.run(MyApp.class, args);
    }
}

Component Scanning & Bean Management

@Component, @Service, @Repository, @Controller

Used to mark classes for component scanning and dependency injection.

@Component     // Generic Spring-managed bean
@Service       // Service-layer component
@Repository    // DAO component
@Controller    // Web controller

@Autowired

Injects dependencies automatically.

@Autowired
private MyService myService;

@Bean

Manually define a bean in a @Configuration class.

@Bean
public MyBean myBean() {
    return new MyBean();
}

Web Development Annotations

@RestController

Marks a class as a RESTful controller. Combines @Controller and @ResponseBody.

@RestController
public class HelloController {
    @GetMapping("/hello")
    public String hello() {
        return "Hello, Spring Boot!";
    }
}

@RequestMapping, @GetMapping, @PostMapping, etc.

Map HTTP requests to controller methods.

@GetMapping("/api/users")
public List<User> getAllUsers() { ... }

@PostMapping("/api/users")
public User createUser(@RequestBody User user) { ... }

@PathVariable & @RequestParam

Extract values from URL path or query parameters.

@GetMapping("/user/{id}")
public User getUser(@PathVariable Long id) { ... }

@GetMapping("/search")
public String search(@RequestParam String q) { ... }

@RequestBody & @ResponseBody

Used to bind or return JSON objects.

Configuration & Profiles

@Configuration

Marks a class that provides Spring bean definitions.

@Value

Injects values from application.properties or application.yml.

@Value("${app.name}")
private String appName;

@Profile

Activates beans only under specific Spring profiles.

@Profile("dev")
@Bean
public DataSource devDataSource() { ... }

Testing Annotations

@SpringBootTest

Runs a full Spring Boot application context for integration testing.

@WebMvcTest, @DataJpaTest

Test specific layers (controllers, repositories) with minimal context.

📌 Bonus Tips

• Use @RestController instead of @Controller + @ResponseBody
• @RequestParam is optional, @PathVariable is required by default
• Keep configuration values external for better flexibility

Conclusion

Spring Boot annotations make your code cleaner, more modular, and easier to manage. Save this cheat sheet and revisit whenever you need a quick reminder or want to onboard a new developer fast.