Update @SendToUser and related code

Issue: SPR-11506

spring-messaging/src/main/java/org/springframework/messaging/simp/annotation/SendToUser.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2014 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.
@@ -26,17 +26,16 @@ import org.springframework.messaging.Message;
 import org.springframework.messaging.simp.SimpMessageHeaderAccessor;
 
 /**
- * Annotation that can be used on methods processing an input message to indicate that the
- * method's return value should be converted to a {@link Message} and sent to the
- * specified destination with the prefix <code>"/user/{username}"</code> automatically
- * prepended with the user information expected to be the input message header
- * {@link SimpMessageHeaderAccessor#USER_HEADER}. Such user destinations may need to be
- * further resolved to actual destinations.
+ * Annotation that indicates the return value of a message-handling method should
+ * be sent as a {@link org.springframework.messaging.Message} to the specified
+ * destination(s) prepended with {@code "/user/{username}"} where the user
+ * name is extracted from the headers of the input message being handled.
  *
  * @author Rossen Stoyanchev
  * @since 4.0
- * @see org.springframework.messaging.handler.annotation.SendTo
+ * @see org.springframework.messaging.simp.annotation.support.SendToMethodReturnValueHandler
  * @see org.springframework.messaging.simp.user.UserDestinationMessageHandler
+ * @see org.springframework.messaging.simp.SimpMessageHeaderAccessor#getUser()
  */
 @Target(ElementType.METHOD)
 @Retention(RetentionPolicy.RUNTIME)
@@ -44,15 +43,20 @@ import org.springframework.messaging.simp.SimpMessageHeaderAccessor;
 public @interface SendToUser {
 
 	/**
-	 * The destination for a message based on the return value of a method.
+	 * One or more destinations to send a message to. If left unspecified, a
+	 * default destination is selected based on the destination of the input
+	 * message being handled.
+	 * @see org.springframework.messaging.simp.annotation.support.SendToMethodReturnValueHandler
 	 */
 	String[] value() default {};
 
 	/**
-     * A flag indicating whether the message is to be sent to a particular user session.
-     *
+	 * Whether messages should be sent to all sessions associated with the user
+	 * or only to the session of the input message being handled.
+	 *
+	 * <p>By default this is set to {@code true} in which case messages are
+	 * broadcast to all sessions.
      */
-    boolean singleSession() default false;
-
+    boolean broadcast() default true;
 
 }

spring-messaging/src/main/java/org/springframework/messaging/simp/annotation/support/SendToMethodReturnValueHandler.java

@@ -16,9 +16,6 @@
 
 package org.springframework.messaging.simp.annotation.support;
 
-import java.lang.annotation.Annotation;
-import java.security.Principal;
-
 import org.springframework.core.MethodParameter;
 import org.springframework.core.annotation.AnnotationUtils;
 import org.springframework.messaging.Message;
@@ -36,6 +33,9 @@ import org.springframework.messaging.support.MessageHeaderInitializer;
 import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
 
+import java.lang.annotation.Annotation;
+import java.security.Principal;
+
 /**
  * A {@link HandlerMethodReturnValueHandler} for sending to destinations specified in a
  * {@link SendTo} or {@link SendToUser} method-level annotations.
@@ -148,11 +148,11 @@ public class SendToMethodReturnValueHandler implements HandlerMethodReturnValueH
 			String user = getUserName(message, headers);
 			String[] destinations = getTargetDestinations(sendToUser, message, this.defaultUserDestinationPrefix);
 			for (String destination : destinations) {
-				if (sendToUser.singleSession()) {
-					this.messagingTemplate.convertAndSendToUser(userName, destination, returnValue, createHeaders(sessionId));
+				if (sendToUser.broadcast()) {
+					this.messagingTemplate.convertAndSendToUser(user, destination, returnValue);
 				}
-				else } 
-					this.messagingTemplate.convertAndSendToUser(userName, destination, returnValue);
+				else {
+					this.messagingTemplate.convertAndSendToUser(user, destination, returnValue, createHeaders(sessionId));
 				}
 			}
 			return;

spring-messaging/src/main/java/org/springframework/messaging/simp/user/DefaultUserDestinationResolver.java

@@ -123,6 +123,7 @@ public class DefaultUserDestinationResolver implements UserDestinationResolver {
 		SimpMessageType messageType = SimpMessageHeaderAccessor.getMessageType(headers);
 		String destination = SimpMessageHeaderAccessor.getDestination(headers);
 		Principal principal = SimpMessageHeaderAccessor.getUser(headers);
+		String sessionId = SimpMessageHeaderAccessor.getSessionId(headers);
 
 		String destinationWithoutPrefix;
 		String subscribeDestination;
@@ -137,7 +138,6 @@ public class DefaultUserDestinationResolver implements UserDestinationResolver {
 				logger.error("Ignoring message, no principal info available");
 				return null;
 			}
-			String sessionId = SimpMessageHeaderAccessor.getSessionId(headers);
 			if (sessionId == null) {
 				logger.error("Ignoring message, no session id available");
 				return null;
@@ -158,12 +158,8 @@ public class DefaultUserDestinationResolver implements UserDestinationResolver {
 			subscribeDestination = this.destinationPrefix.substring(0, startIndex-1) + destinationWithoutPrefix;
 			user = destination.substring(startIndex, endIndex);
 			user = StringUtils.replace(user, "%2F", "/");
-			if (headers.getSessionId() == null){
-				sessionIds = this.userSessionRegistry.getSessionIds(user);				
-			} else {
-				sessionIds = Collections.singleton(headers.getSessionId());
-			}
-
+			sessionIds = (sessionId != null ?
+					Collections.singleton(sessionId) : this.userSessionRegistry.getSessionIds(user));
 		}
 		else {
 			if (logger.isTraceEnabled()) {