From 3be35c053d14d4700f17b3ac4b27e06aa7c6d12e Mon Sep 17 00:00:00 2001
From: Brian Clozel <bclozel@pivotal.io>
Date: Wed, 16 Dec 2015 15:24:35 +0100
Subject: [PATCH] Use LinkedHashmap to preserve insert order

In several places in the spring-webmvc module, URL patterns / objects
relationships are kept in `HashMap`s. When matching with actual URLs,
the algorithm uses a pattern comparator to sort the matching patterns
and select the most specific. But the underlying collection
implementation does not keep the original order which can lead to
inconsistencies.

This commit changes the underlying collection implementation to
`LinkedHashmap`s, in order to keep the insert order if the comparator
does not reorder entries.

Issue: SPR-13798
---
 .../handler/SimpleUrlHandlerMapping.java      |  4 ++--
 .../servlet/resource/ResourceUrlProvider.java |  4 ++--
 .../resource/VersionResourceResolver.java     | 19 ++++++++++---------
 3 files changed, 14 insertions(+), 13 deletions(-)

diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/handler/SimpleUrlHandlerMapping.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/handler/SimpleUrlHandlerMapping.java
index abef0a7ff7e..e34aa0b5a19 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/handler/SimpleUrlHandlerMapping.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/handler/SimpleUrlHandlerMapping.java
@@ -16,7 +16,7 @@
 
 package org.springframework.web.servlet.handler;
 
-import java.util.HashMap;
+import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.Properties;
 
@@ -55,7 +55,7 @@ import org.springframework.util.CollectionUtils;
  */
 public class SimpleUrlHandlerMapping extends AbstractUrlHandlerMapping {
 
-	private final Map<String, Object> urlMap = new HashMap<String, Object>();
+	private final Map<String, Object> urlMap = new LinkedHashMap<String, Object>();
 
 
 	/**
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/resource/ResourceUrlProvider.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/resource/ResourceUrlProvider.java
index 13298ed8bbb..fbd2a55074f 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/resource/ResourceUrlProvider.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/resource/ResourceUrlProvider.java
@@ -19,7 +19,7 @@ package org.springframework.web.servlet.resource;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Comparator;
-import java.util.HashMap;
+import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 import javax.servlet.http.HttpServletRequest;
@@ -55,7 +55,7 @@ public class ResourceUrlProvider implements ApplicationListener<ContextRefreshed
 
 	private PathMatcher pathMatcher = new AntPathMatcher();
 
-	private final Map<String, ResourceHttpRequestHandler> handlerMap = new HashMap<String, ResourceHttpRequestHandler>();
+	private final Map<String, ResourceHttpRequestHandler> handlerMap = new LinkedHashMap<String, ResourceHttpRequestHandler>();
 
 	private boolean autodetect = true;
 
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/resource/VersionResourceResolver.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/resource/VersionResourceResolver.java
index 939f8552335..5a06260766d 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/resource/VersionResourceResolver.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/resource/VersionResourceResolver.java
@@ -19,9 +19,10 @@ package org.springframework.web.servlet.resource;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Comparator;
-import java.util.HashMap;
+import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
+
 import javax.servlet.http.HttpServletRequest;
 
 import org.springframework.core.io.Resource;
@@ -60,7 +61,7 @@ public class VersionResourceResolver extends AbstractResourceResolver {
 	private AntPathMatcher pathMatcher = new AntPathMatcher();
 
 	/** Map from path pattern -> VersionStrategy */
-	private final Map<String, VersionStrategy> versionStrategyMap = new HashMap<String, VersionStrategy>();
+	private final Map<String, VersionStrategy> versionStrategyMap = new LinkedHashMap<String, VersionStrategy>();
 
 
 	/**
@@ -209,17 +210,17 @@ public class VersionResourceResolver extends AbstractResourceResolver {
 	 */
 	protected VersionStrategy getStrategyForPath(String requestPath) {
 		String path = "/".concat(requestPath);
-        List<String> matchingPatterns = new ArrayList<String>();
+		List<String> matchingPatterns = new ArrayList<String>();
 		for (String pattern : this.versionStrategyMap.keySet()) {
 			if (this.pathMatcher.match(pattern, path)) {
-                matchingPatterns.add(pattern);
+				matchingPatterns.add(pattern);
 			}
 		}
-        if (!matchingPatterns.isEmpty()) {
-            Comparator<String> comparator = this.pathMatcher.getPatternComparator(path);
-            Collections.sort(matchingPatterns, comparator);
-            return this.versionStrategyMap.get(matchingPatterns.get(0));
-        }
+		if (!matchingPatterns.isEmpty()) {
+			Comparator<String> comparator = this.pathMatcher.getPatternComparator(path);
+			Collections.sort(matchingPatterns, comparator);
+			return this.versionStrategyMap.get(matchingPatterns.get(0));
+		}
 		return null;
 	}