Cache key classes implement Comparable and consistently provide a toString representation

Issue: SPR-14017

spring-jms/src/main/java/org/springframework/jms/connection/CachingConnectionFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * 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.
@@ -509,7 +509,7 @@ public class CachingConnectionFactory extends SingleConnectionFactory {
 	 * Simple wrapper class around a Destination reference.
 	 * Used as the cache key when caching MessageProducer objects.
 	 */
-	private static class DestinationCacheKey {
+	private static class DestinationCacheKey implements Comparable<DestinationCacheKey> {
 
 		private final Destination destination;
 
@@ -537,7 +537,7 @@ public class CachingConnectionFactory extends SingleConnectionFactory {
 		public boolean equals(Object other) {
 			// Effectively checking object equality as well as toString equality.
 			// On WebSphere MQ, Destination objects do not implement equals...
-			return (other == this || destinationEquals((DestinationCacheKey) other));
+			return (this == other || destinationEquals((DestinationCacheKey) other));
 		}
 
 		@Override
@@ -547,6 +547,16 @@ public class CachingConnectionFactory extends SingleConnectionFactory {
 			// for equivalent destinations... Thanks a lot, WebSphere MQ!
 			return this.destination.getClass().hashCode();
 		}
+
+		@Override
+		public String toString() {
+			return getDestinationString();
+		}
+
+		@Override
+		public int compareTo(DestinationCacheKey other) {
+			return getDestinationString().compareTo(other.getDestinationString());
+		}
 	}
 
 
@@ -584,6 +594,12 @@ public class CachingConnectionFactory extends SingleConnectionFactory {
 					ObjectUtils.nullSafeEquals(this.subscription, otherKey.subscription) &&
 					this.durable == otherKey.durable);
 		}
+
+		@Override
+		public String toString() {
+			return super.toString() + " [selector=" + this.selector + ", noLocal=" + this.noLocal +
+					", subscription=" + this.subscription + ", durable=" + this.durable + "]";
+		}
 	}
 
 }