public void validate(Object target, Errors errors) {
    // 檢查 name 是否為空
    ValidationUtils.rejectIfEmpty(errors, "name", "name.empty");
    Person person = (Person) target;
    // 檢查年齡是否合法
    if (person.getAge() < 0) {
        errors.rejectValue("age", "negative.age", "年齡不能為負(fù)數(shù)！");
    }
}

public class Customer {
    private String firstName;
    private String surname;
    private Address address; // 嵌套對(duì)象
}

public class AddressValidator implements Validator {
    @Override
    public boolean supports(Class<?> clazz) {
        return Address.class.isAssignableFrom(clazz);
    }
    @Override
    public void validate(Object target, Errors errors) {
        ValidationUtils.rejectIfEmpty(errors, "street", "street.empty");
        ValidationUtils.rejectIfEmpty(errors, "city", "city.empty");
    }
}

public class CustomerValidator implements Validator {
    private final Validator addressValidator;
    // 通過(guò)構(gòu)造函數(shù)注入 AddressValidator
    public CustomerValidator(Validator addressValidator) {
        this.addressValidator = addressValidator;
    }
    @Override
    public boolean supports(Class<?> clazz) {
        return Customer.class.isAssignableFrom(clazz);
    }
    @Override
    public void validate(Object target, Errors errors) {
        // 1. 校驗(yàn)客戶(hù)的直屬字段（firstName, surname）
        ValidationUtils.rejectIfEmpty(errors, "firstName", "firstName.empty");
        ValidationUtils.rejectIfEmpty(errors, "surname", "surname.empty");
        Customer customer = (Customer) target;
        Address address = customer.getAddress();
        // 2. 校驗(yàn)嵌套的 Address 對(duì)象
        if (address == null) {
            errors.rejectValue("address", "address.null");
            return;
        }
        // 3. 關(guān)鍵：切換錯(cuò)誤路徑到 "address"，防止字段名沖突
        errors.pushNestedPath("address");
        try {
            ValidationUtils.invokeValidator(addressValidator, address, errors);
        } finally {
            errors.popNestedPath(); // 恢復(fù)原始路徑
        }
    }
}

// 創(chuàng)建 Validator
AddressValidator addressValidator = new AddressValidator();
CustomerValidator customerValidator = new CustomerValidator(addressValidator);
// 準(zhǔn)備測(cè)試數(shù)據(jù)
Customer customer = new Customer();
customer.setFirstName(""); // 空名字
customer.setAddress(new Address()); // 空地址
// 執(zhí)行校驗(yàn)
Errors errors = new BeanPropertyBindingResult(customer, "customer");
customerValidator.validate(customer, errors);
// 輸出錯(cuò)誤
if (errors.hasErrors()) {
    errors.getAllErrors().forEach(error -> {
        System.out.println("字段：" + error.getObjectName() + "." + error.getCode());
    });
}
// 輸出結(jié)果：
// 字段：customer.firstName.empty
// 字段：customer.address.street.empty

public CustomerValidator(Validator addressValidator) {
    if (!addressValidator.supports(Address.class)) {
        throw new IllegalArgumentException("必須支持 Address 類(lèi)型！");
    }
    this.addressValidator = addressValidator;
}

# messages_zh.properties
firstName.empty=名字不能為空
address.street.empty=街道地址不能為空

errors.rejectValue("age", "too.darn.old");

# messages.properties
too.darn.old.age.int=年齡必須是整數(shù)且不超過(guò) 120 歲
too.darn.old.age=年齡不能超過(guò) 120 歲
too.darn.old=輸入的值不合理

// Person.java
public class Person {
    private String name;
    private int age;
    // getters/setters
}
// PersonValidator.java
public class PersonValidator implements Validator {
    @Override
    public boolean supports(Class<?> clazz) {
        return Person.class.isAssignableFrom(clazz);
    }
    @Override
    public void validate(Object target, Errors errors) {
        Person person = (Person) target;
        if (person.getAge() > 120) {
            errors.rejectValue("age", "too.darn.old");
        }
    }
}

# 具體到字段類(lèi)型
too.darn.old.age.int=年齡必須是整數(shù)且不能超過(guò) 120 歲
# 具體到字段
too.darn.old.age=年齡不能超過(guò) 120 歲
# 通用錯(cuò)誤
too.darn.old=輸入的值無(wú)效

@SpringBootTest
public class ValidationTest {
    @Autowired
    private MessageSource messageSource;
    @Test
    public void testAgeValidation() {
        Person person = new Person();
        person.setAge(150); // 觸發(fā)錯(cuò)誤
        Errors errors = new BeanPropertyBindingResult(person, "person");
        PersonValidator validator = new PersonValidator();
        validator.validate(person, errors);
        // 提取錯(cuò)誤消息
        errors.getFieldErrors("age").forEach(error -> {
            String message = messageSource.getMessage(error.getCode(), null, Locale.getDefault());
            System.out.println("錯(cuò)誤消息：" + message);
        });
    }
}

@Configuration
public class ValidationConfig {
    @Bean
    public MessageCodesResolver messageCodesResolver() {
        DefaultMessageCodesResolver resolver = new DefaultMessageCodesResolver();
        resolver.setMessageCodeFormatter(DefaultMessageCodesResolver.Format.POSTFIX_ERROR_CODE);
        return resolver;
    }
}

errors.getFieldErrors("age").forEach(error -> {
    System.out.println("錯(cuò)誤代碼列表：" + Arrays.toString(error.getCodes()));
});