小编典典

我可以在ConstraintValidator中更改Method参数的属性路径吗?

hibernate

如果您熟悉Bean验证框架,那么您将无法获得方法参数的名称。因此,如果对方法的第一个参数执行@NotNull约束,并且验证失败,则getPropertyPath将类似于“
arg1”。

我想创建自己的@NotNull版本,该版本可以采用例如@NamedNotNull(“
emailAddress”)的值。但是我不知道如何在验证器中覆盖#getPropertyPath?有什么办法做到这一点,还是我被“ arg1”或“
arg2”等困扰?

编辑

根据收到的答案,我可以提出以下实现,使我可以从@QueryParam或@PathParam批注中获取值,并将其用作Bean验证批注(如@NotNull)的属性路径。

对于Jersey,您需要创建以下类。注意DefaultParameterNameProvider的实现:

public class ValidationConfigurationContextResolver implements ContextResolver<ValidationConfig> {
    @Override
    public ValidationConfig getContext( final Class<?> type ) {
        final ValidationConfig config = new ValidationConfig();
        config.parameterNameProvider( new RestAnnotationParameterNameProvider() );
        return config;
    }

    static class RestAnnotationParameterNameProvider extends DefaultParameterNameProvider {

        @Override
        public List<String> getParameterNames( Method method ) {
            Annotation[][] annotationsByParam = method.getParameterAnnotations();
            List<String> names = new ArrayList<>( annotationsByParam.length );
            for ( Annotation[] annotations : annotationsByParam ) {
                String name = getParamName( annotations );
                if ( name == null )
                    name = "arg" + ( names.size() + 1 );

                names.add( name );
            }

            return names;
        }

        private static String getParamName( Annotation[] annotations ) {
            for ( Annotation annotation : annotations ) {
                if ( annotation.annotationType() == QueryParam.class ) {
                    return QueryParam.class.cast( annotation ).value();
                }
                else if ( annotation.annotationType() == PathParam.class ) {
                    return PathParam.class.cast( annotation ).value();
                }
            }

            return null;
        }
    }
}

然后在RestConfig中,您需要添加以下行:

register( ValidationConfigurationContextResolver.class );

而已。现在,您的ConstraintValidationExceptions将包含使用其注释的QueryParam或PathParam的名称。例如:

 public void getUser( 
     @NotNull @QueryParam( "emailAddress" ) String emailAddress,
     @NotNull @QueryParam( "password" ) String password ) 
 { ... }

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2020-06-20

共1个答案

小编典典

Bean Validation
1.1引入了ParameterNameProvider用于在创建约束违反对象时为方法和构造函数参数提供名称的接口。


Hibernate Validator
5.2引入了ReflectionParameterNameProvider该类,该ParameterNameProvider实现使用反射来获取实际的参数名称(为了正常工作,它要求使用-parameters编译器参数来编译这些类):

/**
 * Uses Java 8 reflection to get the parameter names.
 * <p>
 * <p>For this provider to return the actual parameter names, classes must be compiled with the '-parameters' compiler
 * argument. Otherwise, the JDK will return synthetic names in the form {@code arg0}, {@code arg1}, etc.</p>
 * <p>
 * <p>See also <a href="http://openjdk.java.net/jeps/118">JEP 118</a></p>
 *
 * @author Khalid Alqinyah
 * @since 5.2
 */
public class ReflectionParameterNameProvider implements ParameterNameProvider {

    @Override
    public List<String> getParameterNames(Constructor<?> constructor) {
        return getParameterNames(constructor.getParameters());
    }

    @Override
    public List<String> getParameterNames(Method method) {
        return getParameterNames(method.getParameters());
    }

    private List<String> getParameterNames(Parameter[] parameters) {

        List<String> parameterNames = newArrayList();
        for (Parameter parameter : parameters) {
            // If '-parameters' is used at compile time, actual names will be returned. Otherwise, it will be arg0, arg1...
            parameterNames.add(parameter.getName());
        }

        return parameterNames;
    }
}

Dropwizard对其进行了扩展,并添加了对JAX-RS
@XxxParam注释的支持,该注释JerseyParameterNameProvider也应与其他JAX-
RS实现一起使用:

/**
 * Adds jersey support to parameter name discovery in hibernate validator.
 * <p>
 * <p>This provider will behave like the hibernate-provided {@link ReflectionParameterNameProvider} except when a
 * method parameter is annotated with a jersey parameter annotation, like {@link QueryParam}. If a jersey parameter
 * annotation is present the value of the annotation is used as the parameter name.</p>
 */
public class JerseyParameterNameProvider extends ReflectionParameterNameProvider {

    @Override
    public List<String> getParameterNames(Method method) {
        Parameter[] parameters = method.getParameters();
        Annotation[][] parameterAnnotations = method.getParameterAnnotations();
        List<String> names = new ArrayList<>(parameterAnnotations.length);
        for (int i = 0; i < parameterAnnotations.length; i++) {
            Annotation[] annotations = parameterAnnotations[i];
            String name = getParameterNameFromAnnotations(annotations).orElse(parameters[i].getName());
            names.add(name);
        }
        return names;
    }

    /**
     * Derives member's name and type from it's annotations
     */
    public static Optional<String> getParameterNameFromAnnotations(Annotation[] memberAnnotations) {

        for (Annotation a : memberAnnotations) {
            if (a instanceof QueryParam) {
                return Optional.of("query param " + ((QueryParam) a).value());
            } else if (a instanceof PathParam) {
                return Optional.of("path param " + ((PathParam) a).value());
            } else if (a instanceof HeaderParam) {
                return Optional.of("header " + ((HeaderParam) a).value());
            } else if (a instanceof CookieParam) {
                return Optional.of("cookie " + ((CookieParam) a).value());
            } else if (a instanceof FormParam) {
                return Optional.of("form field " + ((FormParam) a).value());
            } else if (a instanceof Context) {
                return Optional.of("context");
            } else if (a instanceof MatrixParam) {
                return Optional.of("matrix param " + ((MatrixParam) a).value());
            }
        }

        return Optional.empty();
    }
}

如果不使用Dropwizard,则可以使用上面的代码创建自己的实现。


Validator可以使用ValidationConfigclass
进行定制,以验证Jersey资源类/方法的使用,并通过以下ContextResolver<T>机制将其公开:

public class ValidationConfigurationContextResolver 
        implements ContextResolver<ValidationConfig> {

    @Override
    public ValidationConfig getContext(final Class<?> type) {
        ValidationConfig config = new ValidationConfig();
        config.parameterNameProvider(new CustomParameterNameProvider());
        return config;
    }
}

然后在ValidationConfigurationContextResolver中注册ResourceConfig

有关更多详细信息,请参阅Jersey文档中有关Bean验证的支持

2020-06-20