SpringBoot参数校验之@Valid与@Validated的用法与场景

@PostMapping("/users")
public ResponseEntity<?> createUser(@RequestBody @Valid UserDTO userDTO) {
    // 业务逻辑
    return ResponseEntity.ok().build();
}
public class UserDTO {
    @NotBlank(message = "用户名不能为空")
    private String username;
    @Size(min = 6, max = 20, message = "密码长度需在6-20位")
    private String password;
}

public class OrderDTO {
    @Valid  // 触发嵌套校验
    private UserDTO user;
    @NotNull(message = "订单金额不能为空")
    private BigDecimal amount;
}

public interface CreateGroup {}  // 创建分组
public interface UpdateGroup {}  // 更新分组

public class UserDTO {
    @NotBlank(groups = CreateGroup.class, message = "邮箱不能为空")
    private String email;
    @NotBlank(message = "用户名不能为空")
    private String username;
}

@PostMapping("/users")
public ResponseEntity<?> createUser(
    @RequestBody @Validated(CreateGroup.class) UserDTO userDTO) {
    // 仅校验CreateGroup分组的规则
    return ResponseEntity.ok().build();
}

@Service
@Validated  // 启用方法参数校验
public class UserService {
    public void updateUser(@NotBlank String username, @Min(1) Long userId) {
        // 业务逻辑
    }
}

public class OrderDTO {
    @Validated(CreateGroup.class)  // 指定分组
    @Valid
    private UserDTO user;
    @NotNull(message = "金额必填")
    private BigDecimal amount;
}
// Controller层
@PostMapping("/orders")
public ResponseEntity<?> createOrder(
    @RequestBody @Validated(CreateGroup.class) OrderDTO orderDTO) {
    // 同时校验OrderDTO和UserDTO中CreateGroup分组的规则
    return ResponseEntity.ok().build();
}

@RestControllerAdvice
public class GlobalExceptionHandler {
    @ExceptionHandler(MethodArgumentNotValidException.class)
    public ResponseEntity<?> handleValidationException(MethodArgumentNotValidException ex) {
        Map<String, String> errors = new HashMap<>();
        ex.getBindingResult().getFieldErrors().forEach(error -> 
            errors.put(error.getField(), error.getDefaultMessage()));
        return ResponseEntity.badRequest().body(errors);
    }
}

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-validation</artifactId>
</dependency>