public class User {
    @NotBlank(message = "用戶名不能為空")
    private String username;

    @Email(message = "郵箱格式無(wú)效")
    private String email;

    @Size(min = 6, max = 20, message = "密碼長(zhǎng)度需在6-20位之間")
    private String password;

    @Min(value = 18, message = "年齡必須≥18歲")
    @Max(value = 100, message = "年齡必須≤100歲")
    private Integer age;

    @Pattern(regexp = "^1[3-9]\\d{9}$", message = "手機(jī)號(hào)格式無(wú)效")
    private String phone;
}

<!-- Spring Boot 2.x 使用 javax.validation -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-validation</artifactId>
</dependency>

<!-- Jakarta EE 9+ 使用 jakarta.validation -->
<dependency>
    <groupId>jakarta.validation</groupId>
    <artifactId>jakarta.validation-api</artifactId>
    <version>3.0.2</version>
</dependency>

@PostMapping("/users")
public ResponseEntity<?> createUser(@RequestBody @Valid User user) {
    // 校驗(yàn)通過(guò)后執(zhí)行業(yè)務(wù)邏輯
    return ResponseEntity.ok("用戶創(chuàng)建成功");
}

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

// 定義分組接口
public interface CreateGroup {}
public interface UpdateGroup {}

public class User {
    @NotNull(groups = UpdateGroup.class)
    private Long id;

    @NotBlank(groups = {CreateGroup.class, UpdateGroup.class})
    private String name;
}

// 在 Controller 中指定分組
@PostMapping("/users")
public ResponseEntity<?> createUser(@RequestBody @Validated(CreateGroup.class) User user) { ... }

@Target({FIELD})
@Retention(RUNTIME)
@Constraint(validatedBy = PasswordValidator.class)
public @interface StrongPassword {
    String message() default "密碼必須包含大小寫(xiě)字母和數(shù)字";
    Class<?>[] groups() default {};
    Class<? extends Payload>[] payload() default {};
}

public class PasswordValidator implements ConstraintValidator<StrongPassword, String> {
    @Override
    public boolean isValid(String password, ConstraintValidatorContext context) {
        return password.matches("^(?=.*[a-z])(?=.*[A-Z])(?=.*\\d).+$");
    }
}

public class Order {
    @Valid
    private List<@Valid Product> products; // 校驗(yàn)每個(gè) Product 的字段
}

@Size(min = 6, max = 20, message = "密碼長(zhǎng)度需在{min}-{max}位之間")
private String password;

user.email.invalid=郵箱格式無(wú)效

@Email(message = "{user.email.invalid}")
private String email;