ChannelInterceptor default methods + deprecate adapter

spring-messaging/src/main/java/org/springframework/messaging/simp/broker/AbstractBrokerMessageHandler.java

@@ -34,7 +34,6 @@ import org.springframework.messaging.SubscribableChannel;
 import org.springframework.messaging.simp.SimpMessageHeaderAccessor;
 import org.springframework.messaging.simp.SimpMessageType;
 import org.springframework.messaging.support.ChannelInterceptor;
-import org.springframework.messaging.support.ChannelInterceptorAdapter;
 import org.springframework.messaging.support.InterceptableChannel;
 import org.springframework.util.Assert;
 import org.springframework.util.CollectionUtils;
@@ -274,7 +273,7 @@ public abstract class AbstractBrokerMessageHandler
 	/**
 	 * Detect unsent DISCONNECT messages and process them anyway.
 	 */
-	private class UnsentDisconnectChannelInterceptor extends ChannelInterceptorAdapter {
+	private class UnsentDisconnectChannelInterceptor implements ChannelInterceptor {
 
 		@Override
 		public void afterSendCompletion(

spring-messaging/src/main/java/org/springframework/messaging/support/ChannelInterceptor.java

@@ -38,13 +38,16 @@ public interface ChannelInterceptor {
 	 * send invocation will not occur.
 	 */
 	@Nullable
-	Message<?> preSend(Message<?> message, MessageChannel channel);
+	default Message<?> preSend(Message<?> message, MessageChannel channel) {
+		return message;
+	}
 
 	/**
 	 * Invoked immediately after the send invocation. The boolean
 	 * value argument represents the return value of that invocation.
 	 */
-	void postSend(Message<?> message, MessageChannel channel, boolean sent);
+	default void postSend(Message<?> message, MessageChannel channel, boolean sent) {
+	}
 
 	/**
 	 * Invoked after the completion of a send regardless of any exception that
@@ -53,14 +56,18 @@ public interface ChannelInterceptor {
 	 * completed and returned a Message, i.e. it did not return {@code null}.
 	 * @since 4.1
 	 */
-	void afterSendCompletion(Message<?> message, MessageChannel channel, boolean sent, @Nullable Exception ex);
+	default void afterSendCompletion(Message<?> message, MessageChannel channel, boolean sent,
+			@Nullable Exception ex) {
+	}
 
 	/**
 	 * Invoked as soon as receive is called and before a Message is
 	 * actually retrieved. If the return value is 'false', then no
 	 * Message will be retrieved. This only applies to PollableChannels.
 	 */
-	boolean preReceive(MessageChannel channel);
+	default boolean preReceive(MessageChannel channel) {
+		return true;
+	}
 
 	/**
 	 * Invoked immediately after a Message has been retrieved but before
@@ -69,7 +76,9 @@ public interface ChannelInterceptor {
 	 * This only applies to PollableChannels.
 	 */
 	@Nullable
-	Message<?> postReceive(Message<?> message, MessageChannel channel);
+	default Message<?> postReceive(Message<?> message, MessageChannel channel) {
+		return message;
+	}
 
 	/**
 	 * Invoked after the completion of a receive regardless of any exception that
@@ -78,6 +87,8 @@ public interface ChannelInterceptor {
 	 * completed and returned {@code true}.
 	 * @since 4.1
 	 */
-	void afterReceiveCompletion(@Nullable Message<?> message, MessageChannel channel, @Nullable Exception ex);
+	default void afterReceiveCompletion(@Nullable Message<?> message, MessageChannel channel,
+			@Nullable Exception ex) {
+	}
 
 }

spring-messaging/src/main/java/org/springframework/messaging/support/ChannelInterceptorAdapter.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.
@@ -27,7 +27,11 @@ import org.springframework.messaging.MessageChannel;
  * @author Mark Fisher
  * @author Rossen Stoyanchev
  * @since 4.0
+ * @deprecated as of 5.0.7 {@link ChannelInterceptor} has default methods (made
+ * possible by a Java 8 baseline) and can be implemented directly without the
+ * need for this no-op adapter
  */
+@Deprecated
 public abstract class ChannelInterceptorAdapter implements ChannelInterceptor {
 
 	@Override

spring-messaging/src/main/java/org/springframework/messaging/support/ImmutableMessageChannelInterceptor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 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.
@@ -30,7 +30,7 @@ import org.springframework.messaging.MessageChannel;
  * @author Rossen Stoyanchev
  * @since 4.1.2
  */
-public class ImmutableMessageChannelInterceptor extends ChannelInterceptorAdapter {
+public class ImmutableMessageChannelInterceptor implements ChannelInterceptor {
 
 	@Override
 	public Message<?> preSend(Message<?> message, MessageChannel channel) {

spring-messaging/src/test/java/org/springframework/messaging/simp/config/MessageBrokerConfigurationTests.java

@@ -17,10 +17,8 @@
 package org.springframework.messaging.simp.config;
 
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
-import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 
@@ -64,7 +62,6 @@ import org.springframework.messaging.simp.user.UserDestinationMessageHandler;
 import org.springframework.messaging.simp.user.UserRegistryMessageHandler;
 import org.springframework.messaging.support.AbstractSubscribableChannel;
 import org.springframework.messaging.support.ChannelInterceptor;
-import org.springframework.messaging.support.ChannelInterceptorAdapter;
 import org.springframework.messaging.support.ExecutorSubscribableChannel;
 import org.springframework.messaging.support.MessageBuilder;
 import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
@@ -607,7 +604,7 @@ public class MessageBrokerConfigurationTests {
 	@Configuration
 	static class CustomConfig extends BaseTestMessageBrokerConfig {
 
-		private ChannelInterceptor interceptor = new ChannelInterceptorAdapter() {};
+		private ChannelInterceptor interceptor = new ChannelInterceptor() {};
 
 		@Override
 		protected void configureClientInboundChannel(ChannelRegistration registration) {

spring-messaging/src/test/java/org/springframework/messaging/support/ChannelInterceptorTests.java

@@ -88,7 +88,7 @@ public class ChannelInterceptorTests {
 	public void postSendInterceptorMessageWasSent() {
 		final AtomicBoolean preSendInvoked = new AtomicBoolean(false);
 		final AtomicBoolean completionInvoked = new AtomicBoolean(false);
-		this.channel.addInterceptor(new ChannelInterceptorAdapter() {
+		this.channel.addInterceptor(new ChannelInterceptor() {
 			@Override
 			public void postSend(Message<?> message, MessageChannel channel, boolean sent) {
 				assertInput(message, channel, sent);
@@ -121,7 +121,7 @@ public class ChannelInterceptorTests {
 		};
 		final AtomicBoolean preSendInvoked = new AtomicBoolean(false);
 		final AtomicBoolean completionInvoked = new AtomicBoolean(false);
-		testChannel.addInterceptor(new ChannelInterceptorAdapter() {
+		testChannel.addInterceptor(new ChannelInterceptor() {
 			@Override
 			public void postSend(Message<?> message, MessageChannel channel, boolean sent) {
 				assertInput(message, channel, sent);
@@ -199,7 +199,7 @@ public class ChannelInterceptorTests {
 	}
 
 
-	private abstract static class AbstractTestInterceptor extends ChannelInterceptorAdapter {
+	private abstract static class AbstractTestInterceptor implements ChannelInterceptor {
 
 		private AtomicInteger counter = new AtomicInteger();
 

spring-messaging/src/test/java/org/springframework/messaging/support/ExecutorSubscribableChannelTests.java

@@ -186,8 +186,7 @@ public class ExecutorSubscribableChannelTests {
 	}
 
 
-	private abstract static class AbstractTestInterceptor extends ChannelInterceptorAdapter
-			implements ExecutorChannelInterceptor {
+	private abstract static class AbstractTestInterceptor implements ChannelInterceptor, ExecutorChannelInterceptor {
 
 		private AtomicInteger counter = new AtomicInteger();
 
@@ -209,7 +208,9 @@ public class ExecutorSubscribableChannelTests {
 		}
 
 		@Override
-		public void afterMessageHandled(Message<?> message, MessageChannel channel, MessageHandler handler, Exception ex) {
+		public void afterMessageHandled(Message<?> message, MessageChannel channel, MessageHandler handler,
+				Exception ex) {
+
 			this.afterHandledInvoked = true;
 		}
 	}