Common Spring Boot Annotations and Their Usage

Spring Boot provides several core annotations such as @SpringBootApplication , @Configuration , @EnableAutoConfiguration , and @ComponentScan , which together configure component scanning, auto‑configuration, and bean registration.

Other frequently used annotations include @RestController , @Controller , @ResponseBody , @RequestMapping , @PathVariable , @Autowired , @Qualifier , @Value , and @Resource , each serving specific purposes in request handling, dependency injection, and configuration.

For JPA, annotations like @Entity , @Table , @Id , @GeneratedValue , @OneToOne , @OneToMany , @ManyToOne , @JoinColumn , and @Transient define entity mapping and relationships.

Global exception handling can be centralized with @ControllerAdvice and @ExceptionHandler .

Example code snippets illustrate the usage of these annotations in typical Spring Boot applications:

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication // same as @Configuration @EnableAutoConfiguration @ComponentScan
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

@RequestMapping("/test")
@ResponseBody
public String test(){
    return "ok";
}

@Controller
@RequestMapping("/demoInfo")
public class DemoController {
    @Autowired
    private DemoInfoService demoInfoService;

    @RequestMapping("/hello")
    public String hello(Map
map){
        System.out.println("DemoController.hello()");
        map.put("hello","from TemplateController.helloHtml");
        // will use hello.html or hello.ftl template for rendering
        return "/hello";
    }
}

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/demoInfo2")
public class DemoController2 {
    @RequestMapping("/test")
    public String test(){
        return "ok";
    }
}

@Value(value = "#{message}")
private String message;

@Autowired
@Qualifier(value = "demoInfoService")
private DemoInfoService demoInfoService;

RequestMapping("user/get/mac/{macAddress}")
public String getByMacAddress(@PathVariable String macAddress){
    // do something;
}