如何使用 Hibernate Validator 动态解析消息参数？

Question

我正在使用 Hibernate Validator，并希望解析错误消息中的类别名称。考虑这个简单的场景：

public class Category {
    private String name;
}

public class Product {
    @HazardousCategoryConstraint(message = "{haz.cat.error}")
    private Category category;
    private String name;
}

public class InventoryReport {
    @Valid
    private List<Product> products;
}


ValidationMessages.properties
haz.cat.error={name} is a product in the hazardous category list.

假设我有一个 HazardousCategoryConstraint 的有效实现。验证器根据受限名称列表检查每个类别的名称。当我调用 validate(InventoryReport) 时，我得到了预期的错误数量，只不过它们是相同的字符串。我希望看到类别名称解析到每条消息中。有人可以给我提供一个如何动态解析参数的示例，或者告诉我如何做吗？

Answer 1

IMO，简单的解决方案是创建 javax.validation.MessageInterpolator 的自定义实现。将主要工作委托给 Hibernate Validator 的 ResourceBundleMessageInterpolator 并在 CustomMessageInterpolator 中完成所需的替换工作。

public class CustomMessageInterpolator extends org.hibernate.validator.messageinterpolation.ResourceBundleMessageInterpolator {

    private static final Pattern MESSAGE_PARAMETER_PATTERN = Pattern.compile( "(\\{[^\\}]+?\\})" );

    @Override
    public String interpolate(String message, Context context) {
        String resolvedMessage = super.interpolate(message, context);
        resolvedMessage = replacePropertyNameWithPropertyValues(resolvedMessage, context.getValidatedValue());
        return resolvedMessage;
    }

    private String replacePropertyNameWithPropertyValues(String resolvedMessage, Object validatedValue) {
        Matcher matcher = MESSAGE_PARAMETER_PATTERN.matcher( resolvedMessage );
        StringBuffer sb = new StringBuffer();

        while ( matcher.find() ) {
            String parameter = matcher.group( 1 );

            String propertyName = parameter.replace("{", "");
            propertyName = propertyName.replace("}", "");

            PropertyDescriptor desc = null;
            try {
                desc = new PropertyDescriptor(propertyName, validatedValue.getClass());
            } catch (IntrospectionException ignore) {
                matcher.appendReplacement( sb, parameter );
                continue;
            }

            try {
                Object propertyValue = desc.getReadMethod().invoke(validatedValue);
                matcher.appendReplacement( sb, propertyValue.toString() );
            } catch (Exception ignore) {
                matcher.appendReplacement( sb, parameter );
            }
        }
        matcher.appendTail( sb );
        return sb.toString();
    }

}

@Test

public void validate() {
        Configuration<?> configuration = Validation.byDefaultProvider().configure();
        ValidatorFactory validatorFactory = configuration.messageInterpolator(new CustomMessageInterpolator()).buildValidatorFactory();
        Validator validator = validatorFactory.getValidator();

        Product p = new Product();
        Category cat = new Category();
        cat.setName("s"); //assume specified name is invalid
        p.setCategory(cat);

        Set<ConstraintViolation<Product>> violations = validator.validate(p);
        for(ConstraintViolation<Product> violation : violations) {
            System.out.println(violation.getMessage());
        }
    }

输出

s is a product in the hazardous category list.

Answer 2

public boolean isValid(FooEntity fooEntity, ConstraintValidatorContext context) {


  //do some validation
  boolean result = ...;

  if (!result) {
    HibernateConstraintValidatorContext hibernateContext =
        context.unwrap(HibernateConstraintValidatorContext.class);
    hibernateContext.disableDefaultConstraintViolation();
    hibernateContext
        .addMessageParameter("answer", "Like This!")
        .addExpressionVariable("answer", "Like This!")
        .buildConstraintViolationWithTemplate(hibernateContext.getDefaultConstraintMessageTemplate())
        .addConstraintViolation();
result = false;
  }
  return result;
}

在文件中：

.../resources/ValidationMessages.properties

com.example.validation.DaysLater.message = How do I dynamically resolve message parameters with Hibernate Validator? {answer}