Selector header name is exposed for configuration

Issue: SPR-16732

spring-websocket/src/main/java/org/springframework/web/socket/config/MessageBrokerBeanDefinitionParser.java

@@ -383,6 +383,10 @@ class MessageBrokerBeanDefinitionParser implements BeanDefinitionParser {
 				String heartbeatValue = simpleBrokerElem.getAttribute("heartbeat");
 				brokerDef.getPropertyValues().add("heartbeatValue", heartbeatValue);
 			}
+			if (simpleBrokerElem.hasAttribute("selector-header")) {
+				String headerName = simpleBrokerElem.getAttribute("selector-header");
+				brokerDef.getPropertyValues().add("selectorHeaderName", headerName);
+			}
 		}
 		else if (brokerRelayElem != null) {
 			String prefix = brokerRelayElem.getAttribute("prefix");

spring-websocket/src/main/resources/org/springframework/web/socket/config/spring-websocket.xsd

@@ -384,6 +384,23 @@
                 ]]></xsd:documentation>
 			</xsd:annotation>
 		</xsd:attribute>
+		<xsd:attribute name="selector-header" type="xsd:string">
+			<xsd:annotation>
+				<xsd:documentation source="java:org.springframework.messaging.simp.stomp.SimpleBrokerMessageHandler"><![CDATA[
+	Configure the name of a header that a subscription message can have for
+	the purpose of filtering messages matched to the subscription. The header
+	value is expected to be a Spring EL boolean expression to be applied to
+	the headers of messages matched to the subscription.
+
+	For example:
+	headers.foo == 'bar'
+
+	By default this is set to "selector". You can set it to a different
+	name, or to "" to turn off support for a selector header.
+                ]]></xsd:documentation>
+			</xsd:annotation>
+		</xsd:attribute>
+
 	</xsd:complexType>
 
 	<xsd:complexType name="channel">

spring-websocket/src/test/java/org/springframework/web/socket/config/MessageBrokerBeanDefinitionParserTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -47,6 +47,7 @@ import org.springframework.messaging.handler.invocation.HandlerMethodArgumentRes
 import org.springframework.messaging.handler.invocation.HandlerMethodReturnValueHandler;
 import org.springframework.messaging.simp.SimpMessagingTemplate;
 import org.springframework.messaging.simp.annotation.support.SimpAnnotationMethodMessageHandler;
+import org.springframework.messaging.simp.broker.DefaultSubscriptionRegistry;
 import org.springframework.messaging.simp.broker.SimpleBrokerMessageHandler;
 import org.springframework.messaging.simp.stomp.StompBrokerRelayMessageHandler;
 import org.springframework.messaging.simp.user.DefaultUserDestinationResolver;
@@ -202,6 +203,8 @@ public class MessageBrokerBeanDefinitionParserTests {
 		assertNotNull(brokerMessageHandler);
 		Collection<String> prefixes = brokerMessageHandler.getDestinationPrefixes();
 		assertEquals(Arrays.asList("/topic", "/queue"), new ArrayList<>(prefixes));
+		DefaultSubscriptionRegistry registry = (DefaultSubscriptionRegistry) brokerMessageHandler.getSubscriptionRegistry();
+		assertEquals("my-selector", registry.getSelectorHeaderName());
 		assertNotNull(brokerMessageHandler.getTaskScheduler());
 		assertArrayEquals(new long[] {15000, 15000}, brokerMessageHandler.getHeartbeatValue());
 
@@ -228,7 +231,7 @@ public class MessageBrokerBeanDefinitionParserTests {
 
 		assertNotNull(this.appContext.getBean("webSocketScopeConfigurer", CustomScopeConfigurer.class));
 
-		DirectFieldAccessor accessor = new DirectFieldAccessor(brokerMessageHandler.getSubscriptionRegistry());
+		DirectFieldAccessor accessor = new DirectFieldAccessor(registry);
 		Object pathMatcher = accessor.getPropertyValue("pathMatcher");
 		String pathSeparator = (String) new DirectFieldAccessor(pathMatcher).getPropertyValue("pathSeparator");
 		assertEquals(".", pathSeparator);

spring-websocket/src/test/resources/org/springframework/web/socket/config/websocket-config-broker-simple.xml

@@ -35,7 +35,8 @@
 
 		<websocket:stomp-error-handler ref="errorHandler" />
 
-		<websocket:simple-broker prefix="/topic, /queue" heartbeat="15000,15000" scheduler="scheduler" />
+		<websocket:simple-broker prefix="/topic, /queue" selector-header="my-selector"
+				heartbeat="15000,15000" scheduler="scheduler" />
 
 	</websocket:message-broker>