INT-684 Added support for a Comparator to the FailOverDispatcher

org.springframework.integration/src/main/java/org/springframework/integration/dispatcher/FailOverDispatcher.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2008 the original author or authors.
+ * Copyright 2002-2009 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.
@@ -16,24 +16,51 @@
 
 package org.springframework.integration.dispatcher;
 
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
 import java.util.Iterator;
 import java.util.List;
 
+import org.springframework.core.OrderComparator;
 import org.springframework.integration.message.MessageHandler;
+import org.springframework.util.Assert;
 
 /**
- * {@link AbstractUnicastDispatcher} that will try it's handlers in the
+ * {@link AbstractUnicastDispatcher} that will try its handlers in the
  * same order every dispatch.
  * 
+ * <p>The {@link Comparator} that determines the order may be provided via the
+ * {@link #setComparator(Comparator)} method. If none is provided, the default
+ * will be an instance of {@link OrderComparator}, and any {@link MessageHandler}
+ * that implements {@link org.springframework.core.Ordered} will be ordered
+ * accordingly. Any other handlers will be placed at the end of the list.
+ * 
  * @author Mark Fisher
  * @author Iwein Fuld
  */
 public class FailOverDispatcher extends AbstractUnicastDispatcher {
 
+	@SuppressWarnings("unchecked")
+	private Comparator<Object> comparator = new OrderComparator();
+
+
+	/**
+	 * Provide a {@link Comparator} that will determine the sorting order of
+	 * the handler list and hence the order of the failover chain. If no
+	 * comparator is configured, the default will be an instance of
+	 * {@link OrderComparator}.
+	 */
+	public void setComparator(Comparator<Object> comparator) {
+		Assert.notNull(comparator, "comparator must not be null");
+		this.comparator = comparator;
+	}
 
 	@Override
 	protected Iterator<MessageHandler> getHandlerIterator(List<MessageHandler> handlers) {
-		return handlers.iterator();
+		List<MessageHandler> handlerList = new ArrayList<MessageHandler>(handlers);
+		Collections.sort(handlerList, this.comparator);
+		return handlerList.iterator();
 	}
 
 }

org.springframework.integration/src/main/java/org/springframework/integration/dispatcher/RoundRobinDispatcher.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2008 the original author or authors.
+ * Copyright 2002-2009 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.
@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package org.springframework.integration.dispatcher;
 
 import java.util.ArrayList;
@@ -43,8 +44,8 @@ public class RoundRobinDispatcher extends AbstractUnicastDispatcher {
 	protected Iterator<MessageHandler> getHandlerIterator(List<MessageHandler> handlers) {
 		int size = handlers.size();
 		int nextHandlerStartIndex = getNextHandlerStartIndex(size);
-		List<MessageHandler> reorderedHandlers = new ArrayList<MessageHandler>(handlers.subList(nextHandlerStartIndex,
-				size));
+		List<MessageHandler> reorderedHandlers = new ArrayList<MessageHandler>(
+				handlers.subList(nextHandlerStartIndex, size));
 		reorderedHandlers.addAll(handlers.subList(0, nextHandlerStartIndex));
 		return reorderedHandlers.iterator();
 	}
@@ -58,4 +59,5 @@ public class RoundRobinDispatcher extends AbstractUnicastDispatcher {
 		int indexTail = currentHandlerIndex.getAndIncrement() % size;
 		return indexTail < 0 ? indexTail + size : indexTail;
 	}
+
 }