org.springframework.restdocs.hypermedia.HalLinkExtractor.java Source code

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Here is the source code for org.springframework.restdocs.hypermedia.HalLinkExtractor.java

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/*
 * Copyright 2014-2016 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.restdocs.hypermedia;

import java.util.ArrayList;
import java.util.Collection;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

import org.springframework.http.MediaType;

/**
 * {@link LinkExtractor} that extracts links in Hypermedia Application Language (HAL)
 * format.
 *
 * @author Andy Wilkinson
 */
class HalLinkExtractor extends AbstractJsonLinkExtractor {

    static final MediaType HAL_MEDIA_TYPE = new MediaType("application", "hal+json");

    @Override
    public Map<String, List<Link>> extractLinks(Map<String, Object> json) {
        Map<String, List<Link>> extractedLinks = new LinkedHashMap<>();
        Object possibleLinks = json.get("_links");
        if (possibleLinks instanceof Map) {
            @SuppressWarnings("unchecked")
            Map<String, Object> links = (Map<String, Object>) possibleLinks;
            for (Entry<String, Object> entry : links.entrySet()) {
                String rel = entry.getKey();
                extractedLinks.put(rel, convertToLinks(entry.getValue(), rel));
            }
        }
        return extractedLinks;
    }

    private static List<Link> convertToLinks(Object object, String rel) {
        List<Link> links = new ArrayList<>();
        if (object instanceof Collection) {
            @SuppressWarnings("unchecked")
            Collection<Object> possibleLinkObjects = (Collection<Object>) object;
            for (Object possibleLinkObject : possibleLinkObjects) {
                maybeAddLink(maybeCreateLink(rel, possibleLinkObject), links);
            }
        } else {
            maybeAddLink(maybeCreateLink(rel, object), links);
        }
        return links;
    }

    private static Link maybeCreateLink(String rel, Object possibleLinkObject) {
        if (possibleLinkObject instanceof Map) {
            Map<?, ?> possibleLinkMap = (Map<?, ?>) possibleLinkObject;
            Object hrefObject = possibleLinkMap.get("href");
            if (hrefObject instanceof String) {
                Object titleObject = possibleLinkMap.get("title");
                return new Link(rel, (String) hrefObject,
                        (titleObject instanceof String) ? (String) titleObject : null);
            }
        }
        return null;
    }

    private static void maybeAddLink(Link possibleLink, List<Link> links) {
        if (possibleLink != null) {
            links.add(possibleLink);
        }
    }

}