SpringBoot多场景中23种常用注解详解

一、核心注解

1. @SpringBootApplication
   作用：主配置类注解，组合了@Configuration、@EnableAutoConfiguration和@ComponentScan

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

2. @RestController
   作用：组合了@Controller和@ResponseBody，表示该类是控制器且返回值直接写入HTTP响应体

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

二、依赖注入相关注解
3. @Autowired
作用：自动装配依赖对象

@Service
public class UserService {    
public String getUser() {        return "User Info";   }}
@RestController
public class UserController {@Autowired    private UserService userService;@GetMapping("/user")    public String getUser() {        return userService.getUser();    }}

4. @Component, @Service, @Repository
   作用：将类标记为Spring组件，分别用于通用组件、服务层和数据访问层

@Repository
public class UserRepository {   // 数据访问逻辑}
@Service
public class UserService {@Autowired    private UserRepository userRepository;// 业务逻辑}

三、Web MVC相关注解
5. @RequestMapping
作用：映射Web请求路径

@RestController
@RequestMapping("/api/users")
public class UserController {@RequestMapping(value = "/{id}", method = RequestMethod.GET)    public User getUser(@PathVariable Long id) {        // 获取用户逻辑   }}

6. @GetMapping, @PostMapping, @PutMapping, @DeleteMapping
   作用：特定HTTP方法的简化注解

@RestController
public class UserController {@GetMapping("/users")    public List<User> getAllUsers() {       // 获取所有用户    }@PostMapping("/users")    public User createUser(@RequestBody User user) {        /	/ 创建用户    }@PutMapping("/users/{id}")    public User updateUser(@PathVariable Long id, @RequestBody User user) {        // 更新用户    }@DeleteMapping("/users/{id}")    public void deleteUser(@PathVariable Long id) {        // 删除用户    }}

7. @PathVariable
   作用：获取URL路径中的变量

@GetMapping("/users/{id}")
public User getUser(@PathVariable("id") Long userId) {    // 根据userId获取用户
}

8. @RequestParam
   作用：获取请求参数

 @GetMapping("/users")public List<User> getUsersByPage(        @RequestParam(value = "page", defaultValue = "1") int page,        @RequestParam(value = "size", defaultValue = "10") int size) {    // 分页查询逻辑}

9. @RequestBody
   作用：将HTTP请求体绑定到方法参数
   @PostMapping(“/users”)
   public User createUser(@RequestBody User user) {
   // 创建用户逻辑
   }
10. @ResponseBody
    作用：将方法返回值直接写入HTTP响应体

@Controller
public class UserController {@GetMapping("/user/{id}")    @ResponseBody    public User getUser(@PathVariable Long id) {       // 获取用户逻辑    }}

四、配置相关注解
10. @Configuration
作用：声明一个类为配置类

@Configurationpublic class AppConfig {@Bean    public MyService myService() {        return new MyServiceImpl();    }}

11. @Bean
    作用：声明一个方法的返回值为Bean

@Configuration
public class AppConfig {@Bean    public DataSource dataSource() {        // 配置并返回DataSource   }}

13. @Value
    作用：注入属性值

@Service
public class MyService {@Value("${app.name}")    private String appName;@Value("${app.version:1.0.0}") // 默认值    private String appVersion;
}

14. @ConfigurationProperties
    作用：批量注入配置属性

@Configuration
@ConfigurationProperties(prefix = "app")
public class AppProperties {    private String name;   private String version;    private List<String> servers = new ArrayList<>();// getters and setters
}//application.propertiesapp.name=MyAppapp.version=2.0.0app.servers=server1,server2,server3

五、AOP相关注解1
15. @Aspect
作用：声明一个切面类

 @Aspect@Componentpublic class LoggingAspect {@Before("execution(* com.example.service.*.*(..))")    public void logBefore(JoinPoint joinPoint) {        System.out.println("Before method: " + joinPoint.getSignature().getName());    }@AfterReturning(pointcut = "execution(* com.example.service.*.*(..))",                     returning = "result")    public void logAfterReturning(JoinPoint joinPoint, Object result) {        System.out.println("Method " + joinPoint.getSignature().getName()                           + " returned: " + result);    }} 

六、事务管理
16. @Transactional
作用：声明事务

@Service
public class UserService {@Autowired    private UserRepository userRepository;@Transactional    public User createUser(User user) {        // 事务操作        return userRepository.save(user);    }@Transactional(readOnly = true)    public User getUser(Long id) {        return userRepository.findById(id).orElse(null);    }}

七、测试相关注解
17. @SpringBootTest
作用：Spring Boot集成测试

@SpringBootTest
class UserServiceTest {@Autowired    private UserService userService;@Test    void testCreateUser() {        User user = new User("test", "[e-mail]");        User savedUser = userService.createUser(user);        assertNotNull(savedUser.getId());   }}

18. @MockBean
    作用：在测试中模拟Bean

 @SpringBootTestclass UserServiceTest {@Autowired    private UserService userService;@MockBean    private UserRepository userRepository;@Test    void testGetUser() {        User mockUser = new User(1L, "mock", "[e-mail]");  when(userRepository.findById(1L)).thenReturn(Optional.of(mockUser));User user = userService.getUser(1L);       assertEquals("mock", user.getName());   }}

八、异常处理
19. @ControllerAdvice
作用：全局异常处理

@ControllerAdvice
public class GlobalExceptionHandler {@ExceptionHandler(ResourceNotFoundException.class)    public ResponseEntity<ErrorResponse> handleResourceNotFound(ResourceNotFoundException ex) {        ErrorResponse error = new ErrorResponse("NOT_FOUND", ex.getMessage());       return new ResponseEntity<>(error, HttpStatus.NOT_FOUND);    }@ExceptionHandler(Exception.class)    public ResponseEntity<ErrorResponse> handleAllExceptions(Exception ex) {        ErrorResponse error = new ErrorResponse("INTERNAL_ERROR", "An unexpected error occurred");        return new ResponseEntity<>(error, HttpStatus.INTERNAL_SERVER_ERROR);    }}

九、定时任务
20. @Scheduled
作用：定时任务

 @Componentpublic class ScheduledTasks {private static final Logger log = LoggerFactory.getLogger(ScheduledTasks.class);@Scheduled(fixedRate = 5000) // 每5秒执行一次    public void reportCurrentTime() {        log.info("Current time is {}", new Date());   }@Scheduled(cron = "0 0 12 * * ?") // 每天中午12点执行    public void dailyTask() {        log.info("Executing daily task");    }
}

10、缓存相关
21. @Cacheable, @CacheEvict, @CachePut
作用：声明式缓存

@Service
public class ProductService {@Cacheable(value = "products", key = "#id")    public Product getProductById(Long id) {       // 模拟耗时操作        try {            Thread.sleep(3000);      } catch (InterruptedException e) {            Thread.currentThread().interrupt();       }        return new Product(id, "Product " + id, 100.0);   }@CacheEvict(value = "products", key = "#id")    public void refreshProduct(Long id) {       // 清除缓存   }@CachePut(value = "products", key = "#product.id")    public Product updateProduct(Product product) {        // 更新产品并更新缓存        return product;    }}

十一、验证相关
22. @Valid, @Validated
作用：参数验证

@RestController
public class UserController {@PostMapping("/users")    public ResponseEntity<User> createUser(@Valid @RequestBody User user) {        // 处理验证通过的用户        return ResponseEntity.ok(user);   }}public class User {@NotBlank(message = "Name is mandatory")    private String name;@Email(message = "Email should be valid")    private String email;@Min(value = 18, message = "Age should not be less than 18")    @Max(value = 150, message = "Age should not be greater than 150")    private int age;// getters and setters}

十二、跨域处理
23. @CrossOrigin
作用：处理跨域请求

@RestController
@RequestMapping("/api")
@CrossOrigin(origins = "http://example.com", maxAge = 3600)
public class MyController {@GetMapping("/items")    @CrossOrigin // 可以单独在方法上使用    public List<Item> getItems() {        // 返回项目列表    }
}