/*
* 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.servlet.mvc.condition;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;
import javax.servlet.http.HttpServletRequest;
import org.springframework.http.MediaType;
import org.springframework.web.HttpMediaTypeException;
import org.springframework.web.HttpMediaTypeNotAcceptableException;
import org.springframework.web.accept.ContentNegotiationManager;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.context.request.ServletWebRequest;
import org.springframework.web.cors.CorsUtils;
import org.springframework.web.servlet.mvc.condition.HeadersRequestCondition.HeaderExpression;
/**
* A logical disjunction (' || ') request condition to match a request's 'Accept' header
* to a list of media type expressions. Two kinds of media type expressions are
* supported, which are described in {@link RequestMapping#produces()} and
* {@link RequestMapping#headers()} where the header name is 'Accept'.
* Regardless of which syntax is used, the semantics are the same.
*
* @author Arjen Poutsma
* @author Rossen Stoyanchev
* @since 3.1
*/
public final class ProducesRequestCondition extends AbstractRequestCondition<ProducesRequestCondition> {
private final static ProducesRequestCondition PRE_FLIGHT_MATCH = new ProducesRequestCondition();
private static final ProducesRequestCondition EMPTY_CONDITION = new ProducesRequestCondition();
private final List<ProduceMediaTypeExpression> MEDIA_TYPE_ALL_LIST =
Collections.singletonList(new ProduceMediaTypeExpression("*/*"));
private final List<ProduceMediaTypeExpression> expressions;
private final ContentNegotiationManager contentNegotiationManager;
/**
* Creates a new instance from "produces" expressions. If 0 expressions
* are provided in total, this condition will match to any request.
* @param produces expressions with syntax defined by {@link RequestMapping#produces()}
*/
public ProducesRequestCondition(String... produces) {
this(produces, (String[]) null);
}
/**
* Creates a new instance with "produces" and "header" expressions. "Header"
* expressions where the header name is not 'Accept' or have no header value
* defined are ignored. If 0 expressions are provided in total, this condition
* will match to any request.
* @param produces expressions with syntax defined by {@link RequestMapping#produces()}
* @param headers expressions with syntax defined by {@link RequestMapping#headers()}
*/
public ProducesRequestCondition(String[] produces, String[] headers) {
this(produces, headers, null);
}
/**
* Same as {@link #ProducesRequestCondition(String[], String[])} but also
* accepting a {@link ContentNegotiationManager}.
* @param produces expressions with syntax defined by {@link RequestMapping#produces()}
* @param headers expressions with syntax defined by {@link RequestMapping#headers()}
* @param manager used to determine requested media types
*/
public ProducesRequestCondition(String[] produces, String[] headers, ContentNegotiationManager manager) {
this.expressions = new ArrayList<>(parseExpressions(produces, headers));
Collections.sort(this.expressions);
this.contentNegotiationManager = (manager != null ? manager : new ContentNegotiationManager());
}
/**
* Private constructor with already parsed media type expressions.
*/
private ProducesRequestCondition(Collection<ProduceMediaTypeExpression> expressions, ContentNegotiationManager manager) {
this.expressions = new ArrayList<>(expressions);
Collections.sort(this.expressions);
this.contentNegotiationManager = (manager != null ? manager : new ContentNegotiationManager());
}
private Set<ProduceMediaTypeExpression> parseExpressions(String[] produces, String[] headers) {
Set<ProduceMediaTypeExpression> result = new LinkedHashSet<>();
if (headers != null) {
for (String header : headers) {
HeaderExpression expr = new HeaderExpression(header);
if ("Accept".equalsIgnoreCase(expr.name)) {
for (MediaType mediaType : MediaType.parseMediaTypes(expr.value)) {
result.add(new ProduceMediaTypeExpression(mediaType, expr.isNegated));
}
}
}
}
if (produces != null) {
for (String produce : produces) {
result.add(new ProduceMediaTypeExpression(produce));
}
}
return result;
}
/**
* Return the contained "produces" expressions.
*/
public Set<MediaTypeExpression> getExpressions() {
return new LinkedHashSet<>(this.expressions);
}
/**
* Return the contained producible media types excluding negated expressions.
*/
public Set<MediaType> getProducibleMediaTypes() {
Set<MediaType> result = new LinkedHashSet<>();
for (ProduceMediaTypeExpression expression : this.expressions) {
if (!expression.isNegated()) {
result.add(expression.getMediaType());
}
}
return result;
}
/**
* Whether the condition has any media type expressions.
*/
public boolean isEmpty() {
return this.expressions.isEmpty();
}
@Override
protected List<ProduceMediaTypeExpression> getContent() {
return this.expressions;
}
@Override
protected String getToStringInfix() {
return " || ";
}
/**
* Returns the "other" instance if it has any expressions; returns "this"
* instance otherwise. Practically that means a method-level "produces"
* overrides a type-level "produces" condition.
*/
@Override
public ProducesRequestCondition combine(ProducesRequestCondition other) {
return (!other.expressions.isEmpty() ? other : this);
}
/**
* Checks if any of the contained media type expressions match the given
* request 'Content-Type' header and returns an instance that is guaranteed
* to contain matching expressions only. The match is performed via
* {@link MediaType#isCompatibleWith(MediaType)}.
* @param request the current request
* @return the same instance if there are no expressions;
* or a new condition with matching expressions;
* or {@code null} if no expressions match.
*/
@Override
public ProducesRequestCondition getMatchingCondition(HttpServletRequest request) {
if (CorsUtils.isPreFlightRequest(request)) {
return PRE_FLIGHT_MATCH;
}
if (isEmpty()) {
return this;
}
List<MediaType> acceptedMediaTypes;
try {
acceptedMediaTypes = getAcceptedMediaTypes(request);
}
catch (HttpMediaTypeException ex) {
return null;
}
Set<ProduceMediaTypeExpression> result = new LinkedHashSet<>(expressions);
for (Iterator<ProduceMediaTypeExpression> iterator = result.iterator(); iterator.hasNext();) {
ProduceMediaTypeExpression expression = iterator.next();
if (!expression.match(acceptedMediaTypes)) {
iterator.remove();
}
}
if (!result.isEmpty()) {
return new ProducesRequestCondition(result, this.contentNegotiationManager);
}
else if (acceptedMediaTypes.contains(MediaType.ALL)) {
return EMPTY_CONDITION;
}
else {
return null;
}
}
/**
* Compares this and another "produces" condition as follows:
* <ol>
* <li>Sort 'Accept' header media types by quality value via
* {@link MediaType#sortByQualityValue(List)} and iterate the list.
* <li>Get the first index of matching media types in each "produces"
* condition first matching with {@link MediaType#equals(Object)} and
* then with {@link MediaType#includes(MediaType)}.
* <li>If a lower index is found, the condition at that index wins.
* <li>If both indexes are equal, the media types at the index are
* compared further with {@link MediaType#SPECIFICITY_COMPARATOR}.
* </ol>
* <p>It is assumed that both instances have been obtained via
* {@link #getMatchingCondition(HttpServletRequest)} and each instance
* contains the matching producible media type expression only or
* is otherwise empty.
*/
@Override
public int compareTo(ProducesRequestCondition other, HttpServletRequest request) {
try {
List<MediaType> acceptedMediaTypes = getAcceptedMediaTypes(request);
for (MediaType acceptedMediaType : acceptedMediaTypes) {
int thisIndex = this.indexOfEqualMediaType(acceptedMediaType);
int otherIndex = other.indexOfEqualMediaType(acceptedMediaType);
int result = compareMatchingMediaTypes(this, thisIndex, other, otherIndex);
if (result != 0) {
return result;
}
thisIndex = this.indexOfIncludedMediaType(acceptedMediaType);
otherIndex = other.indexOfIncludedMediaType(acceptedMediaType);
result = compareMatchingMediaTypes(this, thisIndex, other, otherIndex);
if (result != 0) {
return result;
}
}
return 0;
}
catch (HttpMediaTypeNotAcceptableException ex) {
// should never happen
throw new IllegalStateException("Cannot compare without having any requested media types", ex);
}
}
private List<MediaType> getAcceptedMediaTypes(HttpServletRequest request) throws HttpMediaTypeNotAcceptableException {
List<MediaType> mediaTypes = this.contentNegotiationManager.resolveMediaTypes(new ServletWebRequest(request));
return mediaTypes.isEmpty() ? Collections.singletonList(MediaType.ALL) : mediaTypes;
}
private int indexOfEqualMediaType(MediaType mediaType) {
for (int i = 0; i < getExpressionsToCompare().size(); i++) {
MediaType currentMediaType = getExpressionsToCompare().get(i).getMediaType();
if (mediaType.getType().equalsIgnoreCase(currentMediaType.getType()) &&
mediaType.getSubtype().equalsIgnoreCase(currentMediaType.getSubtype())) {
return i;
}
}
return -1;
}
private int indexOfIncludedMediaType(MediaType mediaType) {
for (int i = 0; i < getExpressionsToCompare().size(); i++) {
if (mediaType.includes(getExpressionsToCompare().get(i).getMediaType())) {
return i;
}
}
return -1;
}
private int compareMatchingMediaTypes(ProducesRequestCondition condition1, int index1,
ProducesRequestCondition condition2, int index2) {
int result = 0;
if (index1 != index2) {
result = index2 - index1;
}
else if (index1 != -1) {
ProduceMediaTypeExpression expr1 = condition1.getExpressionsToCompare().get(index1);
ProduceMediaTypeExpression expr2 = condition2.getExpressionsToCompare().get(index2);
result = expr1.compareTo(expr2);
result = (result != 0) ? result : expr1.getMediaType().compareTo(expr2.getMediaType());
}
return result;
}
/**
* Return the contained "produces" expressions or if that's empty, a list
* with a {@code MediaType_ALL} expression.
*/
private List<ProduceMediaTypeExpression> getExpressionsToCompare() {
return (this.expressions.isEmpty() ? MEDIA_TYPE_ALL_LIST : this.expressions);
}
/**
* Parses and matches a single media type expression to a request's 'Accept' header.
*/
class ProduceMediaTypeExpression extends AbstractMediaTypeExpression {
ProduceMediaTypeExpression(MediaType mediaType, boolean negated) {
super(mediaType, negated);
}
ProduceMediaTypeExpression(String expression) {
super(expression);
}
public final boolean match(List<MediaType> acceptedMediaTypes) {
boolean match = matchMediaType(acceptedMediaTypes);
return (!isNegated() ? match : !match);
}
private boolean matchMediaType(List<MediaType> acceptedMediaTypes) {
for (MediaType acceptedMediaType : acceptedMediaTypes) {
if (getMediaType().isCompatibleWith(acceptedMediaType)) {
return true;
}
}
return false;
}
}
}