org.springframework.web.accept.AbstractMappingContentNegotiationStrategy Maven / Gradle / Ivy
/*
* Copyright 2002-2014 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.web.accept;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import org.springframework.http.MediaType;
import org.springframework.util.StringUtils;
import org.springframework.web.HttpMediaTypeNotAcceptableException;
import org.springframework.web.context.request.NativeWebRequest;
/**
* A base class for ContentNegotiationStrategy types that maintain a map with keys
* such as "json" and media types such as "application/json".
*
* @author Rossen Stoyanchev
* @since 3.2
*/
public abstract class AbstractMappingContentNegotiationStrategy extends MappingMediaTypeFileExtensionResolver
implements ContentNegotiationStrategy, MediaTypeFileExtensionResolver {
/**
* Create an instance with the given extension-to-MediaType lookup.
* @throws IllegalArgumentException if a media type string cannot be parsed
*/
public AbstractMappingContentNegotiationStrategy(Map mediaTypes) {
super(mediaTypes);
}
@Override
public List resolveMediaTypes(NativeWebRequest webRequest) throws HttpMediaTypeNotAcceptableException {
String key = getMediaTypeKey(webRequest);
if (StringUtils.hasText(key)) {
MediaType mediaType = lookupMediaType(key);
if (mediaType != null) {
handleMatch(key, mediaType);
return Collections.singletonList(mediaType);
}
mediaType = handleNoMatch(webRequest, key);
if (mediaType != null) {
addMapping(key, mediaType);
return Collections.singletonList(mediaType);
}
}
return Collections.emptyList();
}
/**
* Sub-classes must extract the key to use to look up a media type.
* @return the lookup key or {@code null} if the key cannot be derived
*/
protected abstract String getMediaTypeKey(NativeWebRequest request);
/**
* Invoked when a matching media type is found in the lookup map.
*/
protected void handleMatch(String mappingKey, MediaType mediaType) {
}
/**
* Invoked when no matching media type is found in the lookup map.
* Sub-classes can take further steps to determine the media type.
*/
protected MediaType handleNoMatch(NativeWebRequest request, String key) throws HttpMediaTypeNotAcceptableException {
return null;
}
}