org.springframework.data.web.HateoasPageableHandlerMethodArgumentResolver.java Source code

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Here is the source code for org.springframework.data.web.HateoasPageableHandlerMethodArgumentResolver.java

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/*
 * Copyright 2013-2019 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
 *
 *      https://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 static org.springframework.hateoas.TemplateVariable.VariableType.*;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import org.springframework.core.MethodParameter;
import org.springframework.data.domain.Pageable;
import org.springframework.hateoas.TemplateVariable;
import org.springframework.hateoas.TemplateVariable.VariableType;
import org.springframework.hateoas.TemplateVariables;
import org.springframework.hateoas.server.mvc.UriComponentsContributor;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.MultiValueMap;
import org.springframework.web.util.UriComponents;
import org.springframework.web.util.UriComponentsBuilder;

/**
 * Extension of {@link PageableHandlerMethodArgumentResolver} that also supports enhancing URIs using Spring HATEOAS
 * support.
 *
 * @since 1.6
 * @author Oliver Gierke
 * @author Nick Williams
 */
@SuppressWarnings("null")
public class HateoasPageableHandlerMethodArgumentResolver extends PageableHandlerMethodArgumentResolver
        implements UriComponentsContributor {

    private static final HateoasSortHandlerMethodArgumentResolver DEFAULT_SORT_RESOLVER = new HateoasSortHandlerMethodArgumentResolver();

    private final HateoasSortHandlerMethodArgumentResolver sortResolver;

    /**
     * Constructs an instance of this resolver with a default {@link HateoasSortHandlerMethodArgumentResolver}.
     */
    public HateoasPageableHandlerMethodArgumentResolver() {
        this(null);
    }

    /**
     * Creates a new {@link HateoasPageableHandlerMethodArgumentResolver} using the given
     * {@link HateoasSortHandlerMethodArgumentResolver}..
     *
     * @param sortResolver
     */
    public HateoasPageableHandlerMethodArgumentResolver(
            @Nullable HateoasSortHandlerMethodArgumentResolver sortResolver) {

        super(getDefaultedSortResolver(sortResolver));
        this.sortResolver = getDefaultedSortResolver(sortResolver);
    }

    /**
     * Returns the template variable for the pagination parameters.
     *
     * @param parameter can be {@literal null}.
     * @return
     * @since 1.7
     */
    public TemplateVariables getPaginationTemplateVariables(MethodParameter parameter, UriComponents template) {

        String pagePropertyName = getParameterNameToUse(getPageParameterName(), parameter);
        String sizePropertyName = getParameterNameToUse(getSizeParameterName(), parameter);

        List<TemplateVariable> names = new ArrayList<>();
        MultiValueMap<String, String> queryParameters = template.getQueryParams();
        boolean append = !queryParameters.isEmpty();

        for (String propertyName : Arrays.asList(pagePropertyName, sizePropertyName)) {

            if (!queryParameters.containsKey(propertyName)) {

                VariableType type = append ? REQUEST_PARAM_CONTINUED : REQUEST_PARAM;
                String description = String.format("pagination.%s.description", propertyName);
                names.add(new TemplateVariable(propertyName, type, description));
            }
        }

        TemplateVariables pagingVariables = new TemplateVariables(names);
        return pagingVariables.concat(sortResolver.getSortTemplateVariables(parameter, template));
    }

    /*
     * (non-Javadoc)
     * @see org.springframework.hateoas.server.mvc.UriComponentsContributor#enhance(org.springframework.web.util.UriComponentsBuilder, org.springframework.core.MethodParameter, java.lang.Object)
     */
    @Override
    public void enhance(UriComponentsBuilder builder, @Nullable MethodParameter parameter, Object value) {

        Assert.notNull(builder, "UriComponentsBuilder must not be null!");

        if (!(value instanceof Pageable)) {
            return;
        }

        Pageable pageable = (Pageable) value;

        if (pageable.isUnpaged()) {
            return;
        }

        String pagePropertyName = getParameterNameToUse(getPageParameterName(), parameter);
        String sizePropertyName = getParameterNameToUse(getSizeParameterName(), parameter);

        int pageNumber = pageable.getPageNumber();

        builder.replaceQueryParam(pagePropertyName, isOneIndexedParameters() ? pageNumber + 1 : pageNumber);
        builder.replaceQueryParam(sizePropertyName,
                pageable.getPageSize() <= getMaxPageSize() ? pageable.getPageSize() : getMaxPageSize());

        this.sortResolver.enhance(builder, parameter, pageable.getSort());
    }

    private static HateoasSortHandlerMethodArgumentResolver getDefaultedSortResolver(
            @Nullable HateoasSortHandlerMethodArgumentResolver sortResolver) {
        return sortResolver == null ? DEFAULT_SORT_RESOLVER : sortResolver;
    }
}