SpringBoot参数校验:@Valid与@Validated使用详解

// 需要手动校验每个字段，代码冗余且易出错
public String register(User user) {
    // 手动校验每个字段
    if (user.getEmail() == null || !isValidEmail(user.getEmail())) {
        throw new IllegalArgumentException("邮箱格式错误");
    }
    if (user.getPassword().length() < 8) {
        throw new IllegalArgumentException("密码长度需≥8位");
    }
    // 校验逻辑与业务代码耦合，难以复用
}

public class User {
    @Email(message = "邮箱格式不合法")  // 一行注解替代复杂校验
    private String email;
    
    @Size(min = 8, message = "密码长度需≥8位")
    private String password;
}

@PostMapping("/register")
public String register(@Valid @RequestBody User user) { 
    // 校验逻辑由框架自动处理
    return "success";
}

<!-- pom.xml 必须依赖 -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-validation</artifactId>
</dependency>

public class User {
    @NotNull(message = "用户名不能为空")
    private String name;
    
    @Min(value = 18, message = "年龄必须≥18岁")
    private Integer age;
}

@PostMapping("/users")
public String createUser(@Valid @RequestBody User user) { // 触发校验
    return "success";
}

@RestControllerAdvice
public class GlobalExceptionHandler {
    
    // 处理@Valid/@Validated抛出的校验异常
    @ExceptionHandler(MethodArgumentNotValidException.class)
    public ResponseEntity<Map<String, String>> 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);
    }
}

// 分组接口定义
public interface CreateGroup {} 
public interface UpdateGroup {}

public class User {
    @NotBlank(groups = CreateGroup.class)
    private String name;
    
    @NotNull(groups = {CreateGroup.class, UpdateGroup.class})
    private Integer age;
}

// 使用分组校验
@PostMapping("/users")
public String createUser(@Validated(CreateGroup.class) @RequestBody User user) {
    return "success";
}

// 自定义手机号校验注解
@Documented
@Constraint(validatedBy = PhoneValidator.class)
@Target({FIELD, PARAMETER})
@Retention(RUNTIME)
public @interface Phone {
    String message() default "手机号格式不合法";
    Class<?>[] groups() default {};
    Class<? extends Payload>[] payload() default {};
}

// 校验逻辑实现
public class PhoneValidator implements ConstraintValidator<Phone, String> {
    private static final Pattern PHONE_PATTERN = Pattern.compile("^1[3-9]\\d{9}$");
    
    @Override
    public boolean isValid(String value, ConstraintValidatorContext context) {
        return value != null && PHONE_PATTERN.matcher(value).matches();
    }
}

// 动态分组校验（根据请求参数决定校验组）
@Validated
@RestController
public class UserController {
    
    @PostMapping("/users")
    public String createUser(
        @RequestParam String type,
        @Validated({Default.class, type.equals("vip") ? VipGroup.class : Default.class}) 
        @RequestBody User user
    ) {
        return "success";
    }
}

// 嵌套校验示例
public class Order {
    @Valid  // 必须显式添加
    private User user;
}

// 分组校验示例
@Validated(UpdateGroup.class)
public void updateUser(@RequestBody User user) {}