/*
* Copyright 2002-2016 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
*
* 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.Arrays;
import java.util.Collections;
import java.util.List;
import org.springframework.http.HttpHeaders;
import org.springframework.http.InvalidMediaTypeException;
import org.springframework.http.MediaType;
import org.springframework.web.HttpMediaTypeNotAcceptableException;
import org.springframework.web.context.request.NativeWebRequest;
/**
* A {@code ContentNegotiationStrategy} that checks the 'Accept' request header.
*
* @author Rossen Stoyanchev
* @author Juergen Hoeller
* @since 3.2
*/
public class HeaderContentNegotiationStrategy implements ContentNegotiationStrategy {
/**
* {@inheritDoc}
* @throws HttpMediaTypeNotAcceptableException if the 'Accept' header cannot be parsed
*/
@Override
public List<MediaType> resolveMediaTypes(NativeWebRequest request)
throws HttpMediaTypeNotAcceptableException {
String[] headerValueArray = request.getHeaderValues(HttpHeaders.ACCEPT);
if (headerValueArray == null) {
return Collections.emptyList();
}
List<String> headerValues = Arrays.asList(headerValueArray);
try {
List<MediaType> mediaTypes = MediaType.parseMediaTypes(headerValues);
MediaType.sortBySpecificityAndQuality(mediaTypes);
return mediaTypes;
}
catch (InvalidMediaTypeException ex) {
throw new HttpMediaTypeNotAcceptableException(
"Could not parse 'Accept' header " + headerValues + ": " + ex.getMessage());
}
}
}