Added NullChannel.

org.springframework.integration/src/main/java/org/springframework/integration/channel/NullChannel.java

@@ -0,0 +1,83 @@
+/*
+ * Copyright 2002-2008 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.integration.channel;
+
+import java.util.List;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
+import org.springframework.integration.message.Message;
+import org.springframework.integration.message.selector.MessageSelector;
+
+/**
+ * A channel implementation that essentially behaves like "/dev/null".
+ * All receive() calls will return <em>null</em>, and all send() calls
+ * will return <em>true</em> although no action is performed.
+ * Note however that the invocations are logged at debug-level.
+ * 
+ * @author Mark Fisher
+ */
+public class NullChannel implements MessageChannel {
+
+	private Log logger = LogFactory.getLog(this.getClass());
+
+
+	public List<Message<?>> clear() {
+		return null;
+	}
+
+	/**
+	 * Always returns <code>null</code>.
+	 */
+	public String getName() {
+		return null;
+	}
+
+	public List<Message<?>> purge(MessageSelector selector) {
+		return null;
+	}
+
+	/**
+	 * The channel name cannot be set. It is always <code>null</code>.
+	 */
+	public void setName(String name) {
+	}
+
+	public Message receive() {
+		if (logger.isDebugEnabled()) {
+			logger.debug("receive called on null-channel");
+		}		
+		return null;
+	}
+
+	public Message receive(long timeout) {
+		return this.receive();
+	}
+
+	public boolean send(Message<?> message) {
+		if (logger.isDebugEnabled()) {
+			logger.debug("message sent to null-channel: " + message);
+		}
+		return true;
+	}
+
+	public boolean send(Message<?> message, long timeout) {
+		return this.send(message);
+	}
+
+}