DefaultFileNameGenerator now checks for a filename property on the Message.

spring-integration-core/src/main/java/org/springframework/integration/adapter/file/DefaultFileNameGenerator.java

@@ -17,6 +17,7 @@
 package org.springframework.integration.adapter.file;
 
 import org.springframework.integration.message.Message;
+import org.springframework.util.StringUtils;
 
 /**
  * Default implementation of the filename generator strategy. Concatenates the
@@ -27,7 +28,9 @@ import org.springframework.integration.message.Message;
 public class DefaultFileNameGenerator implements FileNameGenerator {
 
 	public String generateFileName(Message<?> message) {
-		return message.getId() + "-" + System.currentTimeMillis() + ".msg";
+		String filenameProperty = message.getHeader().getProperty(FILENAME_PROPERTY_KEY);
+		return StringUtils.hasText(filenameProperty) ?
+				filenameProperty : message.getId() + "-" + System.currentTimeMillis() + ".msg";
 	}
 
 }

spring-integration-core/src/main/java/org/springframework/integration/adapter/file/FileNameGenerator.java

@@ -25,6 +25,9 @@ import org.springframework.integration.message.Message;
  */
 public interface FileNameGenerator {
 
+	String FILENAME_PROPERTY_KEY = "filename";
+
+
 	String generateFileName(Message<?> message);
 
 }

spring-integration-core/src/test/java/org/springframework/integration/adapter/file/DefaultFileNameGeneratorTests.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright 2002-2007 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.adapter.file;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+import org.junit.Test;
+
+import org.springframework.integration.message.GenericMessage;
+import org.springframework.integration.message.Message;
+
+/**
+ * @author Mark Fisher
+ */
+public class DefaultFileNameGeneratorTests {
+
+	@Test
+	public void testWithFileNamePropertyProvided() {
+		Message<String> message = new GenericMessage<String>("123", "testing");
+		message.getHeader().setProperty(FileNameGenerator.FILENAME_PROPERTY_KEY, "foo.bar");
+		FileNameGenerator generator = new DefaultFileNameGenerator();
+		String filename = generator.generateFileName(message);
+		assertEquals("foo.bar", filename);
+	}
+
+	@Test
+	public void testWithoutFileNamePropertyProvided() {
+		Message<String> message = new GenericMessage<String>("123", "testing");
+		FileNameGenerator generator = new DefaultFileNameGenerator();
+		String filename = generator.generateFileName(message);
+		assertTrue(filename.startsWith("123-"));
+		assertTrue(filename.endsWith(".msg"));
+	}
+
+}