Introduce StompReactorNettyTcpClient

Issue: SPR-11153

spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompBrokerRelayMessageHandler.java

@@ -250,12 +250,22 @@ public class StompBrokerRelayMessageHandler extends AbstractBrokerMessageHandler
 	}
 
 	/**
-	 * Used for unit testing.
+	 * Configure a TCP client for managing TCP connections to the STOMP broker. By default
+	 * {@link org.springframework.messaging.simp.stomp.StompReactorNettyTcpClient} is used.
 	 */
-	void setTcpClient(TcpOperations<byte[]> tcpClient) {
+	public void setTcpClient(TcpOperations<byte[]> tcpClient) {
 		this.tcpClient = tcpClient;
 	}
 
+	/**
+	 * Get the configured TCP client. Never {@code null} unless not configured
+	 * invoked and this method is invoked before the handler is started and
+	 * hence a default implementation initialized.
+	 */
+	public TcpOperations<byte[]> getTcpClient() {
+		return this.tcpClient;
+	}
+
 
 	@Override
 	protected void startInternal() {
@@ -264,7 +274,7 @@ public class StompBrokerRelayMessageHandler extends AbstractBrokerMessageHandler
 		this.brokerChannel.subscribe(this);
 
 		if (this.tcpClient == null) {
-			this.tcpClient = new ReactorNettyTcpClient<byte[]>(this.relayHost, this.relayPort, new StompCodec());
+			this.tcpClient = new StompReactorNettyTcpClient(this.relayHost, this.relayPort);
 		}
 
 		if (logger.isDebugEnabled()) {

spring-messaging/src/main/java/org/springframework/messaging/simp/stomp/StompReactorNettyTcpClient.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2002-2013 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.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.messaging.simp.stomp;
+
+import org.springframework.messaging.tcp.reactor.ReactorNettyTcpClient;
+import reactor.tcp.encoding.Codec;
+
+/**
+ * A variation of {@link ReactorNettyTcpClient} for sending and receiving STOMP frames.
+ *
+ * @author Rossen Stoyanchev
+ * @since 4.0.1
+ */
+public class StompReactorNettyTcpClient extends ReactorNettyTcpClient<byte[]> {
+
+
+	public StompReactorNettyTcpClient(String host, int port) {
+		super(host, port, new StompCodec());
+	}
+
+}

spring-messaging/src/test/java/org/springframework/messaging/simp/stomp/StompBrokerRelayMessageHandlerTests.java

@@ -55,7 +55,7 @@ public class StompBrokerRelayMessageHandlerTests {
 
 		this.brokerRelay = new StompBrokerRelayMessageHandler(new StubMessageChannel(),
 				new StubMessageChannel(), new StubMessageChannel(), Arrays.asList("/topic"));
-		this.brokerRelay.setTcpClient(tcpClient);
+		this.brokerRelay.setTcpClient(this.tcpClient);
 	}