/*
* 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.hateoas.client;
import org.springframework.hateoas.Link;
import org.springframework.hateoas.LinkDiscoverer;
import org.springframework.hateoas.LinkDiscoverers;
import org.springframework.http.MediaType;
import org.springframework.util.Assert;
import com.jayway.jsonpath.JsonPath;
/**
* Helper class to find {@link Link} instances in representations.
*
* @author Oliver Gierke
* @since 0.11
*/
class Rels {
/**
* Creates a new {@link Rel} for the given relation name and {@link LinkDiscoverers}.
*
* @param rel must not be {@literal null} or empty.
* @param discoverers must not be {@literal null}.
* @return
*/
public static Rel getRelFor(String rel, LinkDiscoverers discoverers) {
Assert.hasText(rel, "Relation name must not be null!");
Assert.notNull(discoverers, "LinkDiscoverers must not be null!");
if (rel.startsWith("$")) {
return new JsonPathRel(rel);
}
return new LinkDiscovererRel(rel, discoverers);
}
public interface Rel {
/**
* Returns the link contained in the given representation of the given {@link MediaType}.
*
* @param representation
* @param mediaType
* @return
*/
Link findInResponse(String representation, MediaType mediaType);
}
/**
* {@link Rel} to using a {@link LinkDiscoverer} based on the given {@link MediaType}.
*
* @author Oliver Gierke
*/
private static class LinkDiscovererRel implements Rel {
private final String rel;
private final LinkDiscoverers discoverers;
/**
* Creates a new {@link LinkDiscovererRel} for the given relation name and {@link LinkDiscoverers}.
*
* @param rel must not be {@literal null} or empty.
* @param discoverers must not be {@literal null}.
*/
private LinkDiscovererRel(String rel, LinkDiscoverers discoverers) {
Assert.hasText(rel, "Rel must not be null or empty!");
Assert.notNull(discoverers, "LinkDiscoverers must not be null!");
this.rel = rel;
this.discoverers = discoverers;
}
/*
* (non-Javadoc)
* @see org.springframework.hateoas.client.Rels.Rel#findInResponse(java.lang.String, org.springframework.http.MediaType)
*/
@Override
public Link findInResponse(String response, MediaType mediaType) {
LinkDiscoverer discoverer = discoverers.getLinkDiscovererFor(mediaType);
if (discoverer == null) {
throw new IllegalStateException(String.format("Did not find LinkDiscoverer supporting media type %s!",
mediaType));
}
return discoverer.findLinkWithRel(rel, response);
}
}
/**
* A relation that's being looked up by a JSONPath expression.
*
* @author Oliver Gierke
*/
private static class JsonPathRel implements Rel {
private final String jsonPath;
private final String rel;
/**
* Creates a new {@link JsonPathRel} for the given JSON path.
*
* @param jsonPath must not be {@literal null} or empty.
*/
private JsonPathRel(String jsonPath) {
Assert.hasText(jsonPath, "JSON path must not be null or empty!");
this.jsonPath = jsonPath;
String lastSegment = jsonPath.substring(jsonPath.lastIndexOf('.'));
this.rel = lastSegment.contains("[") ? lastSegment.substring(0, lastSegment.indexOf("[")) : lastSegment;
}
/*
* (non-Javadoc)
* @see org.springframework.hateoas.client.Rels.Rel#findInResponse(java.lang.String, org.springframework.http.MediaType)
*/
@Override
public Link findInResponse(String representation, MediaType mediaType) {
return new Link(JsonPath.<Object> read(representation, jsonPath).toString(), rel);
}
}
}