SpringBoot利用Validation包实现高效参数校验

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

public class User {
    @NotBlank(message = "用户名不能为空")
    @Size(min = 4, max = 20, message = "用户名长度必须在4到20个字符之间")
    private String username;
    
    @NotBlank(message = "密码不能为空")
    @Pattern(regexp = "^(?=.*[a-z])(?=.*[A-Z])(?=.*\\d).{8,}$", 
             message = "密码必须包含大小写字母和数字，且长度不小于8")
    private String password;
    
    @Email(message = "邮箱格式不正确")
    private String email;
}

@PostMapping("/register")
public ResponseEntity<String> registerUser(@RequestBody @Valid User user) {
    // 业务逻辑处理
    return ResponseEntity.ok("注册成功");
}

@Target({ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
@Constraint(validatedBy = PhoneNumberValidator.class)
public @interface PhoneNumber {
    String message() default "手机号格式不正确";
    Class<?>[] groups() default {};
    Class<? extends Payload>[] payload() default {};
}

public class PhoneNumberValidator implements ConstraintValidator<PhoneNumber, String> {
    @Override
    public boolean isValid(String value, ConstraintValidatorContext context) {
        if (value == null) return false;
        return value.matches("^1[3-9]\\d{9}$");
    }
}

@ControllerAdvice
public class GlobalExceptionHandler {
    @ExceptionHandler(MethodArgumentNotValidException.class)
    public ResponseEntity<ErrorResponse> handleValidationException(MethodArgumentNotValidException ex) {
        List<String> errors = ex.getBindingResult()
                .getFieldErrors()
                .stream()
                .map(FieldError::getDefaultMessage)
                .collect(Collectors.toList());
        
        return ResponseEntity.badRequest().body(new ErrorResponse(errors));
    }
}

public class User {
    interface Create {}
    interface Update {}
    
    @NotBlank(groups = {Create.class, Update.class})
    private String username;
    
    @NotBlank(groups = Create.class)
    private String password;
}

@PostMapping("/users")
public ResponseEntity createUser(@RequestBody @Validated(User.Create.class) User user) {
    // ...
}

@PutMapping("/users/{id}")
public ResponseEntity updateUser(@PathVariable Long id, 
                                @RequestBody @Validated(User.Update.class) User user) {
    // ...
}

@SpringBootTest
class UserValidationTest {
    @Autowired
    private Validator validator;
    
    @Test
    void whenUsernameIsBlank_thenValidationFails() {
        User user = new User();
        user.setUsername("");
        user.setPassword("ValidPass123");
        
        Set<ConstraintViolation<User>> violations = validator.validate(user);
        assertFalse(violations.isEmpty());
    }
}