Java tutorial
/* * Copyright 2002-2019 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.messaging.handler; import java.util.ArrayList; import java.util.Collection; import java.util.Collections; import java.util.Comparator; import java.util.Iterator; import java.util.LinkedHashSet; import java.util.List; import java.util.Set; import org.springframework.lang.Nullable; import org.springframework.messaging.Message; import org.springframework.util.AntPathMatcher; import org.springframework.util.CollectionUtils; import org.springframework.util.PathMatcher; import org.springframework.util.RouteMatcher; import org.springframework.util.SimpleRouteMatcher; import org.springframework.util.StringUtils; /** * {@link MessageCondition} to match the destination header of a Message * against one or more patterns through a {@link RouteMatcher}. * * @author Rossen Stoyanchev * @since 4.0 */ public class DestinationPatternsMessageCondition extends AbstractMessageCondition<DestinationPatternsMessageCondition> { /** * The name of the "lookup destination" header. */ public static final String LOOKUP_DESTINATION_HEADER = "lookupDestination"; private final Set<String> patterns; private final RouteMatcher routeMatcher; /** * Constructor with patterns only. Creates and uses an instance of * {@link AntPathMatcher} with default settings. * <p>Non-empty patterns that don't start with "/" are prepended with "/". * @param patterns the URL patterns to match to, or if 0 then always match */ public DestinationPatternsMessageCondition(String... patterns) { this(patterns, (PathMatcher) null); } /** * Constructor with patterns and a {@code PathMatcher} instance. * @param patterns the URL patterns to match to, or if 0 then always match * @param matcher the {@code PathMatcher} to use */ public DestinationPatternsMessageCondition(String[] patterns, @Nullable PathMatcher matcher) { this(patterns, new SimpleRouteMatcher(matcher != null ? matcher : new AntPathMatcher())); } /** * Constructor with patterns and a {@code RouteMatcher} instance. * @param patterns the URL patterns to match to, or if 0 then always match * @param routeMatcher the {@code RouteMatcher} to use * @since 5.2 */ public DestinationPatternsMessageCondition(String[] patterns, RouteMatcher routeMatcher) { this(Collections.unmodifiableSet(prependLeadingSlash(patterns, routeMatcher)), routeMatcher); } private static Set<String> prependLeadingSlash(String[] patterns, RouteMatcher routeMatcher) { boolean slashSeparator = routeMatcher.combine("a", "a").equals("a/a"); Set<String> result = new LinkedHashSet<>(patterns.length); for (String pattern : patterns) { if (slashSeparator && StringUtils.hasLength(pattern) && !pattern.startsWith("/")) { pattern = "/" + pattern; } result.add(pattern); } return result; } private DestinationPatternsMessageCondition(Set<String> patterns, RouteMatcher routeMatcher) { this.patterns = patterns; this.routeMatcher = routeMatcher; } public Set<String> getPatterns() { return this.patterns; } @Override protected Collection<String> getContent() { return this.patterns; } @Override protected String getToStringInfix() { return " || "; } /** * Returns a new instance with URL patterns from the current instance ("this") and * the "other" instance as follows: * <ul> * <li>If there are patterns in both instances, combine the patterns in "this" with * the patterns in "other" using {@link org.springframework.util.PathMatcher#combine(String, String)}. * <li>If only one instance has patterns, use them. * <li>If neither instance has patterns, use an empty String (i.e. ""). * </ul> */ @Override public DestinationPatternsMessageCondition combine(DestinationPatternsMessageCondition other) { Set<String> result = new LinkedHashSet<>(); if (!this.patterns.isEmpty() && !other.patterns.isEmpty()) { for (String pattern1 : this.patterns) { for (String pattern2 : other.patterns) { result.add(this.routeMatcher.combine(pattern1, pattern2)); } } } else if (!this.patterns.isEmpty()) { result.addAll(this.patterns); } else if (!other.patterns.isEmpty()) { result.addAll(other.patterns); } else { result.add(""); } return new DestinationPatternsMessageCondition(result, this.routeMatcher); } /** * Check if any of the patterns match the given Message destination and return an instance * that is guaranteed to contain matching patterns, sorted via * {@link org.springframework.util.PathMatcher#getPatternComparator(String)}. * @param message the message to match to * @return the same instance if the condition contains no patterns; * or a new condition with sorted matching patterns; * or {@code null} either if a destination can not be extracted or there is no match */ @Override @Nullable public DestinationPatternsMessageCondition getMatchingCondition(Message<?> message) { Object destination = message.getHeaders().get(LOOKUP_DESTINATION_HEADER); if (destination == null) { return null; } if (this.patterns.isEmpty()) { return this; } List<String> matches = null; for (String pattern : this.patterns) { if (pattern.equals(destination) || matchPattern(pattern, destination)) { if (matches == null) { matches = new ArrayList<>(); } matches.add(pattern); } } if (CollectionUtils.isEmpty(matches)) { return null; } matches.sort(getPatternComparator(destination)); return new DestinationPatternsMessageCondition(new LinkedHashSet<>(matches), this.routeMatcher); } private boolean matchPattern(String pattern, Object destination) { return destination instanceof RouteMatcher.Route ? this.routeMatcher.match(pattern, (RouteMatcher.Route) destination) : ((SimpleRouteMatcher) this.routeMatcher).getPathMatcher().match(pattern, (String) destination); } private Comparator<String> getPatternComparator(Object destination) { return destination instanceof RouteMatcher.Route ? this.routeMatcher.getPatternComparator((RouteMatcher.Route) destination) : ((SimpleRouteMatcher) this.routeMatcher).getPathMatcher() .getPatternComparator((String) destination); } /** * Compare the two conditions based on the destination patterns they contain. * Patterns are compared one at a time, from top to bottom via * {@link org.springframework.util.PathMatcher#getPatternComparator(String)}. * If all compared patterns match equally, but one instance has more patterns, * it is considered a closer match. * <p>It is assumed that both instances have been obtained via * {@link #getMatchingCondition(Message)} to ensure they contain only patterns * that match the request and are sorted with the best matches on top. */ @Override public int compareTo(DestinationPatternsMessageCondition other, Message<?> message) { Object destination = message.getHeaders().get(LOOKUP_DESTINATION_HEADER); if (destination == null) { return 0; } Comparator<String> patternComparator = getPatternComparator(destination); Iterator<String> iterator = this.patterns.iterator(); Iterator<String> iteratorOther = other.patterns.iterator(); while (iterator.hasNext() && iteratorOther.hasNext()) { int result = patternComparator.compare(iterator.next(), iteratorOther.next()); if (result != 0) { return result; } } if (iterator.hasNext()) { return -1; } else if (iteratorOther.hasNext()) { return 1; } else { return 0; } } }