From 0c6b99e489689521e7661fb6ee53acdca444e827 Mon Sep 17 00:00:00 2001
From: Arjen Poutsma <apoutsma@vmware.com>
Date: Wed, 3 Feb 2010 11:38:31 +0000
Subject: [PATCH] SPR-6788 - The class MediaType has a natural ordering that is
 inconsistent with equals, which is generally recommended or should otherwise
 at least be indicated in the javadoc

---
 .../org/springframework/http/MediaType.java   | 16 +++++++--
 .../springframework/http/MediaTypeTests.java  | 36 ++++++++++++++++++-
 2 files changed, 49 insertions(+), 3 deletions(-)

diff --git a/org.springframework.web/src/main/java/org/springframework/http/MediaType.java b/org.springframework.web/src/main/java/org/springframework/http/MediaType.java
index e86624a3e2e..0411c3b546c 100644
--- a/org.springframework.web/src/main/java/org/springframework/http/MediaType.java
+++ b/org.springframework.web/src/main/java/org/springframework/http/MediaType.java
@@ -20,12 +20,12 @@ import java.nio.charset.Charset;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.Comparator;
 import java.util.Iterator;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
-import java.util.Comparator;
 
 import org.springframework.util.Assert;
 import org.springframework.util.CollectionUtils;
@@ -44,7 +44,7 @@ import org.springframework.util.StringUtils;
  * @see <a href="http://tools.ietf.org/html/rfc2616#section-3.7">HTTP 1.1, section 3.7</a>
  * @since 3.0
  */
-public class MediaType {
+public class MediaType implements Comparable<MediaType> {
 
 	public static final MediaType ALL = new MediaType("*", "*");
 
@@ -213,6 +213,18 @@ public class MediaType {
 		return isWildcardType();
 	}
 
+	/**
+	 * Compares this {@link MediaType} to another alphabetically.
+	 *
+	 * @param other media type to compare to
+	 * @see #sortBySpecificity(List)
+	 */
+	public int compareTo(MediaType other) {
+		String s1 = this.toString();
+		String s2 = other.toString();
+		return s1.compareToIgnoreCase(s2);
+	}
+
 	@Override
 	public boolean equals(Object other) {
 		if (this == other) {
diff --git a/org.springframework.web/src/test/java/org/springframework/http/MediaTypeTests.java b/org.springframework.web/src/test/java/org/springframework/http/MediaTypeTests.java
index d1180c5b407..4a315d3e6c7 100644
--- a/org.springframework.web/src/test/java/org/springframework/http/MediaTypeTests.java
+++ b/org.springframework.web/src/test/java/org/springframework/http/MediaTypeTests.java
@@ -19,8 +19,8 @@ package org.springframework.http;
 import java.nio.charset.Charset;
 import java.util.ArrayList;
 import java.util.Collections;
-import java.util.List;
 import java.util.Comparator;
+import java.util.List;
 import java.util.Random;
 
 import static org.junit.Assert.*;
@@ -111,6 +111,40 @@ public class MediaTypeTests {
 		assertEquals("Invalid amount of media types", 0, mediaTypes.size());
 	}
 
+	@Test
+	public void compareTo() {
+		MediaType audioBasic = new MediaType("audio", "basic");
+		MediaType audio = new MediaType("audio");
+		MediaType audioWave = new MediaType("audio", "wave");
+		MediaType audioBasicLevel = new MediaType("audio", "basic", Collections.singletonMap("level", "1"));
+
+		// equal
+		assertEquals("Invalid comparison result", 0, audioBasic.compareTo(audioBasic));
+		assertEquals("Invalid comparison result", 0, audio.compareTo(audio));
+		assertEquals("Invalid comparison result", 0, audioBasicLevel.compareTo(audioBasicLevel));
+
+		assertTrue("Invalid comparison result", audioBasicLevel.compareTo(audio) > 0);
+
+		List<MediaType> expected = new ArrayList<MediaType>();
+		expected.add(audio);
+		expected.add(audioBasic);
+		expected.add(audioBasicLevel);
+		expected.add(audioWave);
+
+		List<MediaType> result = new ArrayList<MediaType>(expected);
+		Random rnd = new Random();
+		// shuffle & sort 10 times
+		for (int i = 0; i < 10; i++) {
+			Collections.shuffle(result, rnd);
+			Collections.sort(result);
+
+			for (int j = 0; j < result.size(); j++) {
+				assertSame("Invalid media type at " + j, expected.get(j), result.get(j));
+			}
+		}
+
+	}
+
 	@Test
 	public void specificityComparator() throws Exception {
 		MediaType audioBasic = new MediaType("audio", "basic");