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* Licensed to the Apache Software Foundation (ASF) under one
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* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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
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package org.apache.wink.server.internal.registry;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.ListIterator;
import java.util.Map;
import java.util.Properties;
import java.util.Set;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import javax.ws.rs.WebApplicationException;
import javax.ws.rs.core.HttpHeaders;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.Response.ResponseBuilder;
import org.apache.wink.common.RuntimeContext;
import org.apache.wink.common.WinkApplication;
import org.apache.wink.common.http.HttpHeadersEx;
import org.apache.wink.common.http.HttpStatus;
import org.apache.wink.common.internal.application.ApplicationValidator;
import org.apache.wink.common.internal.i18n.Messages;
import org.apache.wink.common.internal.lifecycle.LifecycleManagersRegistry;
import org.apache.wink.common.internal.registry.Injectable;
import org.apache.wink.common.internal.registry.metadata.MethodMetadata;
import org.apache.wink.common.internal.uritemplate.UriTemplateMatcher;
import org.apache.wink.common.internal.uritemplate.UriTemplateProcessor;
import org.apache.wink.common.internal.utils.HeaderUtils;
import org.apache.wink.common.internal.utils.MediaTypeUtils;
import org.apache.wink.common.internal.utils.SoftConcurrentMap;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Registry for maintaining a set of all the known root resources and finding
* the dispatch method of a request, following the JAX-RS spec.
*/
public class ResourceRegistry {
private static final Logger logger =
LoggerFactory
.getLogger(ResourceRegistry.class);
private List<ResourceRecord> rootResources;
private ResourceRecordFactory resourceRecordsFactory;
private Lock readersLock;
private Lock writersLock;
private final ApplicationValidator applicationValidator;
private HashMap<Boolean, SoftConcurrentMap<String, ArrayList<ResourceRecord>>> uriToResourceCache =
new HashMap<Boolean, SoftConcurrentMap<String, ArrayList<ResourceRecord>>>();
public ResourceRegistry(LifecycleManagersRegistry factoryRegistry,
ApplicationValidator applicationValidator) {
this(factoryRegistry, applicationValidator, new Properties());
}
public ResourceRegistry(LifecycleManagersRegistry factoryRegistry,
ApplicationValidator applicationValidator,
Properties properties) {
this.applicationValidator = applicationValidator;
rootResources = new LinkedList<ResourceRecord>();
resourceRecordsFactory = new ResourceRecordFactory(factoryRegistry, properties);
ReadWriteLock readWriteLock = new ReentrantReadWriteLock();
readersLock = readWriteLock.readLock();
writersLock = readWriteLock.writeLock();
uriToResourceCache.put(Boolean.TRUE,
new SoftConcurrentMap<String, ArrayList<ResourceRecord>>());
uriToResourceCache.put(Boolean.FALSE,
new SoftConcurrentMap<String, ArrayList<ResourceRecord>>());
}
/**
* Add a resource as an object to the registry
*
* @param instance the object to add
*/
public void addResource(Object instance) {
addResource(instance, WinkApplication.DEFAULT_PRIORITY);
}
/**
* Add a resource class to the registry
*
* @param clazz the resource class to add
*/
public void addResource(Class<?> clazz) {
addResource(clazz, WinkApplication.DEFAULT_PRIORITY);
}
/**
* Add a resource as an object to the registry with a priority
*
* @param clazz the resource class to add
* @param priority priority of the resource
*/
public void addResource(Object instance, double priority) {
logger.trace("Adding resource instance: {} with priority: {}", instance, priority); //$NON-NLS-1$
writersLock.lock();
try {
if (!applicationValidator.isValidResource(instance.getClass())) {
if (logger.isWarnEnabled()) {
logger.warn(Messages
.getMessage("resourceClassNotValid", instance.getClass().getName())); //$NON-NLS-1$
}
return;
}
ResourceRecord record = getRecord(instance);
record.setPriority(priority);
rootResources.add(record);
assertSorted();
} finally {
writersLock.unlock();
}
}
/**
* Add a resource class to the registry with a priority
*
* @param clazz the resource class to add
* @param priority priority of the resource
*/
public void addResource(Class<?> clazz, double priority) {
logger.trace("Adding resource class: {} with priority: {}", clazz, priority); //$NON-NLS-1$
writersLock.lock();
try {
if (!applicationValidator.isValidResource(clazz)) {
if (logger.isWarnEnabled()) {
logger.warn(Messages.getMessage("resourceClassNotValid", clazz.getName())); //$NON-NLS-1$
}
return;
}
ResourceRecord record = getRecord(clazz);
record.setPriority(priority);
rootResources.add(record);
assertSorted();
} finally {
writersLock.unlock();
}
}
/**
* Removes all the root resource records.
*/
public void removeAllResources() {
writersLock.lock();
try {
for (ResourceRecord record : rootResources) {
record.getObjectFactory().releaseAll(null);
}
rootResources.clear();
assertSorted();
} finally {
writersLock.unlock();
}
}
/**
* Get the {@link ResourceRecord} of the specified root resource instance.
* This is a shortcut for {@code getRecord(instance, true)}
*
* @param instance the resource instance to get the record for
* @return {@link ResourceRecord} of the instance
*/
public ResourceRecord getRecord(Object instance) {
return getRecord(instance, true);
}
/**
* Get the {@link ResourceRecord} of the specified resource instance
*
* @param instance the resource instance to get the record for
* @param isRootResource specifies whether the instance is a root resource
* (true) or sub-resource (false)
* @return {@link ResourceRecord} of the instance
*/
public ResourceRecord getRecord(Object instance, boolean isRootResource) {
return resourceRecordsFactory.getResourceRecord(instance, isRootResource);
}
/**
* Get the {@link ResourceRecord} of the specified resource class
*
* @param clazz the resource class to get the record for
* @return {@link ResourceRecord} of the instance
*/
public ResourceRecord getRecord(Class<?> clazz) {
return resourceRecordsFactory.getResourceRecord(clazz);
}
/**
* Get the list of all the root resource records
*
* @return unmodifiable list of all the root resource records
*/
public List<ResourceRecord> getRecords() {
readersLock.lock();
try {
return Collections.unmodifiableList(rootResources);
} finally {
readersLock.unlock();
}
}
public Set<String> getOptions(ResourceInstance resource) {
Set<String> set = new HashSet<String>();
List<MethodMetadata> resourceMethods;
if (resource.isExactMatch()) {
resourceMethods = resource.getRecord().getMetadata().getResourceMethods();
} else {
String uri = UriTemplateProcessor.normalizeUri(resource.getMatcher().getTail(false));
List<SubResourceInstance> matchingMethods =
resource.getRecord().getMatchingSubResourceMethods(uri);
resourceMethods = new LinkedList<MethodMetadata>();
for (SubResourceInstance subResource : matchingMethods) {
resourceMethods.add(subResource.getRecord().getMetadata());
}
}
for (MethodMetadata method : resourceMethods) {
set.add(method.getHttpMethod());
}
return set;
}
/**
* Verify that the root resources list is sorted
*/
private void assertSorted() {
// we use the reverse-order comparator because the sort method
// will sort the elements in ascending order, but we want
// them sorted in descending order
Collections.sort(rootResources, Collections.reverseOrder());
uriToResourceCache.get(Boolean.TRUE).clear();
uriToResourceCache.get(Boolean.FALSE).clear();
}
/**
* Get a list of all the root resources that match the request.
*
* @param context
* @return
*/
public List<ResourceInstance> getMatchingRootResources(String uri) {
return getMatchingRootResources(uri, true);
}
/**
* Get a list of all the root resources that match the request.
*
* @param context
* @return
*/
public List<ResourceInstance> getMatchingRootResources(String uri,
boolean isContinuedSearchPolicy) {
if (uri == null) {
uri = ""; //$NON-NLS-1$
}
if (uri.startsWith("/")) { //$NON-NLS-1$
uri = uri.substring(1);
}
ArrayList<ResourceInstance> found = new ArrayList<ResourceInstance>(1);
ArrayList<ResourceRecord> previousMatched = null;
/*
* the previous matches are cached so if a previous URI used is still in
* the cache, this will find the resources that matched skipping the
* expensive UriTemplateMatcher.matches()
*/
previousMatched = uriToResourceCache.get(isContinuedSearchPolicy).get(uri);
if (previousMatched != null) {
for (ResourceRecord record : previousMatched) {
UriTemplateMatcher matcher = record.getTemplateProcessor().matcher();
if (matcher.matches(uri)) {
found.add(new ResourceInstance(record, matcher));
}
}
return found;
}
readersLock.lock();
try {
previousMatched = new ArrayList<ResourceRecord>();
// the list of root resource records is already sorted
for (ResourceRecord record : rootResources) {
UriTemplateMatcher matcher = record.getTemplateProcessor().matcher();
if (matcher.matches(uri)) {
if (matcher.isExactMatch() || record.hasSubResources()) {
previousMatched.add(record);
found.add(new ResourceInstance(record, matcher));
if (!isContinuedSearchPolicy) {
break;
}
}
}
}
uriToResourceCache.get(isContinuedSearchPolicy).put(uri, previousMatched);
} finally {
readersLock.unlock();
}
return found;
}
/**
* Attempts to find a resource method to invoke in the specified resource
*
* @param resource the resource to find the method in
* @param variablesValues a multivalued map of variables values that stores
* the variables of the templates that are matched during the
* search
* @param context the context of the current request
* @return
*/
public MethodRecord findMethod(ResourceInstance resource, RuntimeContext context)
throws WebApplicationException {
List<MethodMetadata> methods = resource.getRecord().getMetadata().getResourceMethods();
List<MethodMetadataRecord> records = new LinkedList<MethodMetadataRecord>();
for (MethodMetadata metadata : methods) {
records.add(new MethodMetadataRecord(metadata));
}
// filter the methods according to the spec
filterDispatchMethods(resource, records, context);
// select the best matching method
return selectBestMatchingMethod(records, context);
}
/**
* Attempts to find a sub-resource method to invoke in the specified
* resource
*
* @param pattern the regex pattern that the 'path' specified on the
* sub-resource method must match
* @param subResourceRecords a list of all the sub-resources (methods and
* locators) in the specified resource that matched the request
* @param resource the resource to find the method in
* @param variablesValues a multivalued map of variables values that stores
* the variables of the templates that are matched during the
* search
* @param context the context of the current request
* @return
*/
public SubResourceInstance findSubResourceMethod(String pattern,
List<SubResourceInstance> subResourceRecords,
ResourceInstance resource,
RuntimeContext context)
throws WebApplicationException {
// extract the sub-resource methods that have the same path template
// as the first sub-resource method
List<SubResourceInstance> subResourceMethods =
extractSubResourceMethods(pattern, subResourceRecords);
// filter the methods according to http method/consumes/produces
filterDispatchMethods(resource, subResourceMethods, context);
// select the best matching method
return (SubResourceInstance)selectBestMatchingMethod(subResourceMethods, context);
}
/**
* Extract the sub-resource methods from the specified list that have the
* same path pattern as the specified pattern
*
* @param pattern
* @param subResourceRecords
* @return a list of sub-resource methods whose 'path' pattern match the
* specified pattern
*/
private List<SubResourceInstance> extractSubResourceMethods(String pattern,
List<SubResourceInstance> subResourceRecords) {
List<SubResourceInstance> subResourceMethods = new LinkedList<SubResourceInstance>();
for (SubResourceInstance instance : subResourceRecords) {
SubResourceRecord record = instance.getRecord();
String recordPattern = record.getTemplateProcessor().getPatternString();
if (record instanceof SubResourceMethodRecord && recordPattern.equals(pattern)) {
subResourceMethods.add(instance);
}
}
return subResourceMethods;
}
/**
* Filter the methods that do not conform to the current request by
* modifying the input list:
* <ol>
* <li>Filter all methods that do not match the http method of the request.
* If a method does not have an http method, it passes the filter.</li>
* <li>Filter all methods that do not match the media type of the input
* entity. If a method does not have the @Consumes annotation, it passes the
* filter</li>
* <li>Filter all methods that do not match the Accept header. If a method
* does not have the @Produces annotation, it passes the filter</li>
* </ol>
* The elements in the list remain in the same order
*
* @param resource
* @param methodRecords a list of method records to filter according to the
* request context
* @param context the context of the current request
* @return
*/
private void filterDispatchMethods(ResourceInstance resource,
List<? extends MethodRecord> methodRecords,
RuntimeContext context) throws WebApplicationException {
// filter by http method
ListIterator<? extends MethodRecord> iterator = methodRecords.listIterator();
while (iterator.hasNext()) {
MethodRecord record = iterator.next();
if (filterByHttpMethod(record, context)) {
iterator.remove();
}
}
if (methodRecords.size() == 0) {
if (logger.isInfoEnabled()) {
logger.info(Messages.getMessage("noMethodInClassSupportsHTTPMethod", resource //$NON-NLS-1$
.getResourceClass().getName(), context.getRequest().getMethod()));
}
Set<String> httpMethods = getOptions(resource);
ResponseBuilder builder = Response.status(HttpStatus.METHOD_NOT_ALLOWED.getCode());
// add 'Allow' header to the response
String allowHeader = HeaderUtils.buildOptionsHeader(httpMethods);
builder.header(HttpHeadersEx.ALLOW, allowHeader);
throw new WebApplicationException(builder.build());
}
// filter by consumes
iterator = methodRecords.listIterator();
while (iterator.hasNext()) {
MethodRecord record = iterator.next();
if (filterByConsumes(record, context)) {
iterator.remove();
}
}
if (methodRecords.size() == 0) {
logger.info(Messages.getMessage("noMethodInClassConsumesHTTPMethod", resource //$NON-NLS-1$
.getResourceClass().getName(), context.getHttpHeaders().getMediaType()));
throw new WebApplicationException(Response.Status.UNSUPPORTED_MEDIA_TYPE);
}
// filter by produces
iterator = methodRecords.listIterator();
while (iterator.hasNext()) {
MethodRecord record = iterator.next();
if (filterByProduces(record, context)) {
iterator.remove();
}
}
if (methodRecords.size() == 0) {
logger.info(Messages.getMessage("noMethodInClassProducesHTTPMethod", resource //$NON-NLS-1$
.getResourceClass().getName(), context.getHttpHeaders()
.getRequestHeader(HttpHeaders.ACCEPT)));
throw new WebApplicationException(Response.Status.NOT_ACCEPTABLE);
}
}
/**
* Checks if the method record matches the http method of the request
*
* @param record the method record to check
* @param context the context of the current request
* @return true if the method should be filtered, false otherwise
*/
private boolean filterByHttpMethod(MethodRecord record, RuntimeContext context) {
String httpMethod = context.getRequest().getMethod();
String recordHttpMethod = record.getMetadata().getHttpMethod();
// non existing http method (with a path on the method),
// then it's a sub-resource locator and it's ok
if (recordHttpMethod == null) {
return false;
}
// the http method is different than the request http method,
// then the resource method should be filtered
if (!recordHttpMethod.equals(httpMethod)) {
return true;
}
return false;
}
/**
* Checks if the method record matches the media type of the input entity
*
* @param record the method record to check
* @param context the context of the current request
* @return true if the method should be filtered, false otherwise
*/
private boolean filterByConsumes(MethodRecord record, RuntimeContext context) {
Set<MediaType> consumedMimes = record.getMetadata().getConsumes();
// if not specified, then treat as if consumes */*
if (consumedMimes.size() == 0) {
return false;
}
MediaType inputMediaType = context.getHttpHeaders().getMediaType();
if (inputMediaType == null) {
inputMediaType = MediaType.APPLICATION_OCTET_STREAM_TYPE;
}
for (MediaType mediaType : consumedMimes) {
if (mediaType.isCompatible(inputMediaType)) {
return false;
}
}
return true;
}
/**
* Checks if the method record matches the Accept header of the request
*
* @param record the method record to check
* @param context the context of the current request
* @return true if the method should be filtered, false otherwise
*/
private boolean filterByProduces(MethodRecord record, RuntimeContext context) {
Set<MediaType> producedMimes = record.getMetadata().getProduces();
// if not specified, then treat as if produces */*
if (producedMimes.size() == 0) {
return false;
}
List<MediaType> receivedMediaTypes = context.getHttpHeaders().getAcceptableMediaTypes();
// if no accept media type was specified
if (receivedMediaTypes.size() == 0) {
return false;
}
List<MediaType> deniableMediaTypes = new LinkedList<MediaType>();
List<MediaType> acceptableMediaTypes = new LinkedList<MediaType>();
for (MediaType received : receivedMediaTypes) {
String q = received.getParameters().get("q"); //$NON-NLS-1$
if (q != null && Double.valueOf(q).equals(0.0)) {
deniableMediaTypes.add(received);
} else {
acceptableMediaTypes.add(received);
}
}
l1: for (MediaType mediaType : producedMimes) {
for (MediaType deniable : deniableMediaTypes) {
if (MediaTypeUtils.isCompatibleNonCommutative(deniable, mediaType)) {
continue l1;
}
}
for (MediaType acceptableMediaType : acceptableMediaTypes) {
if (mediaType.isCompatible(acceptableMediaType)) {
return false;
}
}
}
return true;
}
/**
* Select the method that best matches the details of the request by
* comparing the media types of the input entity and those specified in the
* Accept header
*
* @param methodRecords the list of methods to select the best match from
* @param context the context of the current request
* @return
*/
private MethodRecord selectBestMatchingMethod(List<? extends MethodRecord> methodRecords,
RuntimeContext context) {
HttpHeaders httpHeaders = context.getHttpHeaders();
MediaType inputMediaType = httpHeaders.getMediaType();
List<MediaType> acceptableMediaTypes = httpHeaders.getAcceptableMediaTypes();
MethodRecord bestMatch = null;
for (MethodRecord record : methodRecords) {
if (compareMethods(record, bestMatch, inputMediaType, acceptableMediaTypes) > 0) {
bestMatch = record;
}
}
return bestMatch;
}
/**
* Compare two methods in terms of "which is a better match to the request".
* First a match to the input media type is compared, then a match to the
* Accept header media types is compared
*
* @param record1 the first method
* @param record2 the second method
* @param inputMediaType the input entity media type
* @param acceptableMediaTypes the media types of the Accept header
* @return positive integer if record1 is a better match, negative integer
* if record2 is a better match, 0 if they are equal in matching
* terms
*/
private int compareMethods(MethodRecord record1,
MethodRecord record2,
MediaType inputMediaType,
List<MediaType> acceptableMediaTypes) {
if (record1 == null && record2 == null) {
return 0;
}
if (record1 != null && record2 == null) {
return 1;
}
if (record1 == null && record2 != null) {
return -1;
}
// compare consumes
int res = compareMethodsConsumes(record1, record2, inputMediaType);
if (res != 0) {
return res;
}
// compare produces
res = compareMethodsProduces(record1, record2, acceptableMediaTypes);
if (res != 0) {
return res;
}
// this is just to make the search a bit more deterministic,
// and it should remain undocumented and application implementors
// should not rely on this behavior (i.e. comparing the number of
// parameters)
return compareMethodsParameters(record1, record2);
}
/**
* Compares two methods the in terms of the number of parameters
*
* @param record1 the first method
* @param record2 the second method
* @return positive integer if record1 has more parameters, negative integer
* if record2 has more parameters, 0 if they are equal in number of
* parameters
*/
private int compareMethodsParameters(MethodRecord record1, MethodRecord record2) {
List<Injectable> params1 = record1.getMetadata().getFormalParameters();
List<Injectable> params2 = record2.getMetadata().getFormalParameters();
return params1.size() - params2.size();
}
/**
* Compare two methods in terms of matching to the input media type
*
* @param record1 the first method
* @param record2 the second method
* @param inputMediaType the input entity media type
* @return positive integer if record1 is a better match, negative integer
* if record2 is a better match, 0 if they are equal in matching
* terms
*/
private int compareMethodsConsumes(MethodRecord record1,
MethodRecord record2,
MediaType inputMediaType) {
// get media type of metadata 1 best matching the input media type
MediaType bestMatch1 =
selectBestMatchingMediaType(inputMediaType, record1.getMetadata().getConsumes());
// get media type of metadata 2 best matching the input media type
MediaType bestMatch2 =
selectBestMatchingMediaType(inputMediaType, record2.getMetadata().getConsumes());
if (bestMatch1 == null && bestMatch2 == null) {
return 0;
}
if (bestMatch1 != null && bestMatch2 == null) {
return 1;
}
if (bestMatch1 == null && bestMatch2 != null) {
return -1;
}
int retVal = MediaTypeUtils.compareTo(bestMatch1, bestMatch2);
if (retVal != 0) {
return retVal;
}
Map<String, String> inputParameters = inputMediaType.getParameters();
Map<String, String> bestMatch1Params = bestMatch1.getParameters();
boolean didMatchAllParamsForBestMatch1 = true;
for (String key : bestMatch1Params.keySet()) {
String inputValue = inputParameters.get(key);
String value1 = bestMatch1Params.get(key);
if (!value1.equals(inputValue)) {
didMatchAllParamsForBestMatch1 = false;
break;
}
}
Map<String, String> bestMatch2Params = bestMatch2.getParameters();
boolean didMatchAllParamsForBestMatch2 = true;
for (String key : bestMatch2Params.keySet()) {
String inputValue = inputParameters.get(key);
String value2 = bestMatch2Params.get(key);
if (!value2.equals(inputValue)) {
didMatchAllParamsForBestMatch2 = false;
break;
}
}
if (didMatchAllParamsForBestMatch1 && !didMatchAllParamsForBestMatch2) {
return 1;
}
if (!didMatchAllParamsForBestMatch1 && didMatchAllParamsForBestMatch2) {
return -1;
}
if (didMatchAllParamsForBestMatch1 && didMatchAllParamsForBestMatch2) {
int size1 = bestMatch1Params.size();
int size2 = bestMatch2Params.size();
if (size1 > size2) {
return 1;
} else if (size2 > size1) {
return -1;
}
}
return 0;
}
/**
* Compare two methods in terms of matching to the Accept header media types
*
* @param record1 the first method
* @param record2 the second method
* @param acceptableMediaTypes the media types of the Accept header
* @return positive integer if record1 is a better match, negative integer
* if record2 is a better match, 0 if they are equal in matching
* terms
*/
private int compareMethodsProduces(MethodRecord record1,
MethodRecord record2,
List<MediaType> acceptableMediaTypes) {
MediaType bestMatch1 = null;
MediaType bestMatch2 = null;
// the acceptMediaTypes list is already sorted according to preference
// of media types,
// so we need to stop with the first media type that has a match
for (MediaType acceptableMediaType : acceptableMediaTypes) {
// get media type of metadata 1 best matching the current acceptable
// media type
bestMatch1 =
selectBestMatchingMediaType(acceptableMediaType, record1.getMetadata()
.getProduces());
// get media type of metadata 2 best matching the current acceptable
// media type
bestMatch2 =
selectBestMatchingMediaType(acceptableMediaType, record2.getMetadata()
.getProduces());
// if either of them returned a match, it's enough for a comparison
if (bestMatch1 != null || bestMatch2 != null) {
break;
}
}
if (bestMatch1 == null && bestMatch2 == null) {
return 0;
}
if (bestMatch1 != null && bestMatch2 == null) {
return 1;
}
if (bestMatch1 == null && bestMatch2 != null) {
return -1;
}
return MediaTypeUtils.compareTo(bestMatch1, bestMatch2);
}
/**
* Select the media type from the list of media types that best matches the
* specified media type
*
* @param mediaType the media type to match against
* @param mediaTypes the list of media types to select the best match from
* @return the best matching media type from the list
*/
private MediaType selectBestMatchingMediaType(MediaType mediaType, Set<MediaType> mediaTypes) {
MediaType bestMatch = null;
for (MediaType mt : mediaTypes) {
if (!mt.isCompatible(mediaType)) {
continue;
}
if (bestMatch == null || MediaTypeUtils.compareTo(mt, bestMatch) > 0) {
bestMatch = mt;
}
}
if (bestMatch == null) {
return null;
}
return bestMatch;
}
}