org.springframework.web.servlet.mvc.condition.ProducesRequestCondition Maven / Gradle / Ivy
/*
* Copyright 2002-2020 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
*
* https://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.Collections;
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.lang.Nullable;
import org.springframework.util.CollectionUtils;
import org.springframework.util.ObjectUtils;
import org.springframework.util.StringUtils;
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 {
private static final ContentNegotiationManager DEFAULT_CONTENT_NEGOTIATION_MANAGER =
new ContentNegotiationManager();
private static final ProducesRequestCondition EMPTY_CONDITION = new ProducesRequestCondition();
private static final List MEDIA_TYPE_ALL_LIST =
Collections.singletonList(new ProduceMediaTypeExpression(MediaType.ALL_VALUE));
private static final String MEDIA_TYPES_ATTRIBUTE = ProducesRequestCondition.class.getName() + ".MEDIA_TYPES";
private final List 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, null, 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, @Nullable 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, @Nullable String[] headers,
@Nullable ContentNegotiationManager manager) {
this.expressions = parseExpressions(produces, headers);
if (this.expressions.size() > 1) {
Collections.sort(this.expressions);
}
this.contentNegotiationManager = manager != null ? manager : DEFAULT_CONTENT_NEGOTIATION_MANAGER;
}
private List parseExpressions(String[] produces, @Nullable String[] headers) {
Set result = null;
if (!ObjectUtils.isEmpty(headers)) {
for (String header : headers) {
HeaderExpression expr = new HeaderExpression(header);
if ("Accept".equalsIgnoreCase(expr.name) && expr.value != null) {
for (MediaType mediaType : MediaType.parseMediaTypes(expr.value)) {
result = (result != null ? result : new LinkedHashSet<>());
result.add(new ProduceMediaTypeExpression(mediaType, expr.isNegated));
}
}
}
}
if (!ObjectUtils.isEmpty(produces)) {
for (String produce : produces) {
result = (result != null ? result : new LinkedHashSet<>());
result.add(new ProduceMediaTypeExpression(produce));
}
}
return (result != null ? new ArrayList<>(result) : Collections.emptyList());
}
/**
* Private constructor for internal use to create matching conditions.
* Note the expressions List is neither sorted nor deep copied.
*/
private ProducesRequestCondition(List expressions, ProducesRequestCondition other) {
this.expressions = expressions;
this.contentNegotiationManager = other.contentNegotiationManager;
}
/**
* Return the contained "produces" expressions.
*/
public Set getExpressions() {
return new LinkedHashSet<>(this.expressions);
}
/**
* Return the contained producible media types excluding negated expressions.
*/
public Set getProducibleMediaTypes() {
Set 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.
*/
@Override
public boolean isEmpty() {
return this.expressions.isEmpty();
}
@Override
protected List 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
@Nullable
public ProducesRequestCondition getMatchingCondition(HttpServletRequest request) {
if (CorsUtils.isPreFlightRequest(request)) {
return EMPTY_CONDITION;
}
if (isEmpty()) {
return this;
}
List acceptedMediaTypes;
try {
acceptedMediaTypes = getAcceptedMediaTypes(request);
}
catch (HttpMediaTypeException ex) {
return null;
}
List result = getMatchingExpressions(acceptedMediaTypes);
if (!CollectionUtils.isEmpty(result)) {
return new ProducesRequestCondition(result, this);
}
else if (MediaType.ALL.isPresentIn(acceptedMediaTypes)) {
return EMPTY_CONDITION;
}
else {
return null;
}
}
@Nullable
private List getMatchingExpressions(List acceptedMediaTypes) {
List result = null;
for (ProduceMediaTypeExpression expression : this.expressions) {
if (expression.match(acceptedMediaTypes)) {
result = result != null ? result : new ArrayList<>();
result.add(expression);
}
}
return result;
}
/**
* Compares this and another "produces" condition as follows:
*
* - Sort 'Accept' header media types by quality value via
* {@link MediaType#sortByQualityValue(List)} and iterate the list.
*
- 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)}.
*
- If a lower index is found, the condition at that index wins.
*
- If both indexes are equal, the media types at the index are
* compared further with {@link MediaType#SPECIFICITY_COMPARATOR}.
*
* 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 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);
}
}
@SuppressWarnings("unchecked")
private List getAcceptedMediaTypes(HttpServletRequest request)
throws HttpMediaTypeNotAcceptableException {
List result = (List) request.getAttribute(MEDIA_TYPES_ATTRIBUTE);
if (result == null) {
result = this.contentNegotiationManager.resolveMediaTypes(new ServletWebRequest(request));
request.setAttribute(MEDIA_TYPES_ATTRIBUTE, result);
}
return result;
}
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 {@value MediaType#ALL_VALUE} expression.
*/
private List getExpressionsToCompare() {
return (this.expressions.isEmpty() ? MEDIA_TYPE_ALL_LIST : this.expressions);
}
/**
* Use this to clear {@link #MEDIA_TYPES_ATTRIBUTE} that contains the parsed,
* requested media types.
* @param request the current request
* @since 5.2
*/
public static void clearMediaTypesAttribute(HttpServletRequest request) {
request.removeAttribute(MEDIA_TYPES_ATTRIBUTE);
}
/**
* Parses and matches a single media type expression to a request's 'Accept' header.
*/
static class ProduceMediaTypeExpression extends AbstractMediaTypeExpression {
ProduceMediaTypeExpression(MediaType mediaType, boolean negated) {
super(mediaType, negated);
}
ProduceMediaTypeExpression(String expression) {
super(expression);
}
public final boolean match(List acceptedMediaTypes) {
boolean match = matchMediaType(acceptedMediaTypes);
return !isNegated() == match;
}
private boolean matchMediaType(List acceptedMediaTypes) {
for (MediaType acceptedMediaType : acceptedMediaTypes) {
if (getMediaType().isCompatibleWith(acceptedMediaType) && matchParameters(acceptedMediaType)) {
return true;
}
}
return false;
}
private boolean matchParameters(MediaType acceptedMediaType) {
for (String name : getMediaType().getParameters().keySet()) {
String s1 = getMediaType().getParameter(name);
String s2 = acceptedMediaType.getParameter(name);
if (StringUtils.hasText(s1) && StringUtils.hasText(s2) && !s1.equalsIgnoreCase(s2)) {
return false;
}
}
return true;
}
}
}