/*
* Copyright 2013-2014 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.data.web;
import java.util.List;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.core.MethodParameter;
import org.springframework.data.domain.Pageable;
import org.springframework.hateoas.Link;
import org.springframework.hateoas.MethodLinkBuilderFactory;
import org.springframework.hateoas.core.MethodParameters;
import org.springframework.hateoas.mvc.ControllerLinkBuilderFactory;
import org.springframework.web.bind.support.WebDataBinderFactory;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.method.support.HandlerMethodArgumentResolver;
import org.springframework.web.method.support.ModelAndViewContainer;
import org.springframework.web.util.UriComponents;
import org.springframework.web.util.UriComponentsBuilder;
/**
* {@link HandlerMethodArgumentResolver} to allow injection of {@link PagedResourcesAssembler} into Spring MVC
* controller methods.
*
* @since 1.6
* @author Oliver Gierke
* @author Nick Williams
*/
public class PagedResourcesAssemblerArgumentResolver implements HandlerMethodArgumentResolver {
private static final Logger LOGGER = LoggerFactory.getLogger(PagedResourcesAssemblerArgumentResolver.class);
private static final String SUPERFLOUS_QUALIFIER = "Found qualified {} parameter, but a unique unqualified {} parameter. Using that one, but you might wanna check your controller method configuration!";
private static final String PARAMETER_AMBIGUITY = "Discovered muliple parameters of type Pageable but no qualifier annotations to disambiguate!";
private final HateoasPageableHandlerMethodArgumentResolver resolver;
private final MethodLinkBuilderFactory<?> linkBuilderFactory;
/**
* Creates a new {@link PagedResourcesAssemblerArgumentResolver} using the given
* {@link PageableHandlerMethodArgumentResolver} and {@link MethodLinkBuilderFactory}.
*
* @param resolver can be {@literal null}.
* @param linkBuilderFactory can be {@literal null}, will be defaulted to a {@link ControllerLinkBuilderFactory}.
*/
public PagedResourcesAssemblerArgumentResolver(HateoasPageableHandlerMethodArgumentResolver resolver,
MethodLinkBuilderFactory<?> linkBuilderFactory) {
this.resolver = resolver;
this.linkBuilderFactory = linkBuilderFactory == null ? new ControllerLinkBuilderFactory() : linkBuilderFactory;
}
/*
* (non-Javadoc)
* @see org.springframework.web.method.support.HandlerMethodArgumentResolver#supportsParameter(org.springframework.core.MethodParameter)
*/
@Override
public boolean supportsParameter(MethodParameter parameter) {
return PagedResourcesAssembler.class.equals(parameter.getParameterType());
}
/*
* (non-Javadoc)
* @see org.springframework.web.method.support.HandlerMethodArgumentResolver#resolveArgument(org.springframework.core.MethodParameter, org.springframework.web.method.support.ModelAndViewContainer, org.springframework.web.context.request.NativeWebRequest, org.springframework.web.bind.support.WebDataBinderFactory)
*/
@Override
public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer,
NativeWebRequest webRequest, WebDataBinderFactory binderFactory) {
UriComponents fromUriString = resolveBaseUri(parameter);
MethodParameter pageableParameter = findMatchingPageableParameter(parameter);
if (pageableParameter != null) {
return new MethodParameterAwarePagedResourcesAssembler<Object>(pageableParameter, resolver, fromUriString);
} else {
return new PagedResourcesAssembler<Object>(resolver, fromUriString);
}
}
/**
* Eagerly resolve a base URI for the given {@link MethodParameter} to be handed to the assembler.
*
* @param parameter must not be {@literal null}.
* @return the {@link UriComponents} representing the base URI, or {@literal null} if it can't be resolved eagerly.
*/
private UriComponents resolveBaseUri(MethodParameter parameter) {
try {
Link linkToMethod = linkBuilderFactory.linkTo(parameter.getDeclaringClass(), parameter.getMethod()).withSelfRel();
return UriComponentsBuilder.fromUriString(linkToMethod.getHref()).build();
} catch (IllegalArgumentException o_O) {
return null;
}
}
/**
* Returns finds the {@link MethodParameter} for a {@link Pageable} instance matching the given
* {@link MethodParameter} requesting a {@link PagedResourcesAssembler}.
*
* @param parameter must not be {@literal null}.
* @return
*/
private static final MethodParameter findMatchingPageableParameter(MethodParameter parameter) {
MethodParameters parameters = new MethodParameters(parameter.getMethod());
List<MethodParameter> pageableParameters = parameters.getParametersOfType(Pageable.class);
Qualifier assemblerQualifier = parameter.getParameterAnnotation(Qualifier.class);
if (pageableParameters.isEmpty()) {
return null;
}
if (pageableParameters.size() == 1) {
MethodParameter pageableParameter = pageableParameters.get(0);
MethodParameter matchingParameter = returnIfQualifiersMatch(pageableParameter, assemblerQualifier);
if (matchingParameter == null) {
LOGGER.info(SUPERFLOUS_QUALIFIER, PagedResourcesAssembler.class.getSimpleName(), Pageable.class.getName());
}
return pageableParameter;
}
if (assemblerQualifier == null) {
throw new IllegalStateException(PARAMETER_AMBIGUITY);
}
for (MethodParameter pageableParameter : pageableParameters) {
MethodParameter matchingParameter = returnIfQualifiersMatch(pageableParameter, assemblerQualifier);
if (matchingParameter != null) {
return matchingParameter;
}
}
throw new IllegalStateException(PARAMETER_AMBIGUITY);
}
private static MethodParameter returnIfQualifiersMatch(MethodParameter pageableParameter, Qualifier assemblerQualifier) {
if (assemblerQualifier == null) {
return pageableParameter;
}
Qualifier pageableParameterQualifier = pageableParameter.getParameterAnnotation(Qualifier.class);
if (pageableParameterQualifier == null) {
return null;
}
return pageableParameterQualifier.value().equals(assemblerQualifier.value()) ? pageableParameter : null;
}
}