Added PayloadTransformer strategy interface, MethodInvokingPayloadTransformer, and PayloadTransformingMessageHandler.

org.springframework.integration/src/main/java/org/springframework/integration/transformer/MethodInvokingPayloadTransformer.java

@@ -16,24 +16,15 @@
 
 package org.springframework.integration.transformer;
 
-import org.springframework.integration.handler.MessageHandler;
-import org.springframework.integration.message.Message;
+import org.springframework.integration.util.AbstractMethodInvokingAdapter;
 
 /**
  * @author Mark Fisher
  */
-public class TransformerMessageHandlerAdapter implements MessageHandler {
+public class MethodInvokingPayloadTransformer extends AbstractMethodInvokingAdapter implements PayloadTransformer<Object, Object> {
 
-	private final MessageTransformer transformer;
-
-
-	public TransformerMessageHandlerAdapter(MessageTransformer transformer) {
-		this.transformer = transformer;
-	}
-
-
-	public Message<?> handle(Message<?> message) {
-		return this.transformer.transform(message);
+	public Object transform(Object payload) throws Exception {
+		return this.invokeMethod(payload); 
 	}
 
 }

org.springframework.integration/src/main/java/org/springframework/integration/transformer/PayloadTransformer.java

@@ -0,0 +1,26 @@
+/*
+ * 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.transformer;
+
+/**
+ * @author Mark Fisher
+ */
+public interface PayloadTransformer<T, U> {
+
+	U transform(T payload) throws Exception;
+
+}

org.springframework.integration/src/main/java/org/springframework/integration/transformer/PayloadTransformingMessageHandler.java

@@ -16,20 +16,30 @@
 
 package org.springframework.integration.transformer;
 
+import org.springframework.integration.handler.MessageHandler;
 import org.springframework.integration.message.Message;
 import org.springframework.integration.message.MessageBuilder;
 import org.springframework.integration.message.MessagingException;
-import org.springframework.integration.util.AbstractMethodInvokingAdapter;
+import org.springframework.util.Assert;
 
 /**
  * @author Mark Fisher
  */
-public class PayloadTransformerAdapter extends AbstractMethodInvokingAdapter implements MessageTransformer {
+@SuppressWarnings("unchecked")
+public class PayloadTransformingMessageHandler implements MessageHandler {
 
-	@SuppressWarnings("unchecked")
-	public Message<?> transform(Message<?> message) {
+	private final PayloadTransformer transformer;
+
+
+	public PayloadTransformingMessageHandler(PayloadTransformer transformer) {
+		Assert.notNull(transformer, "transformer must not be null");
+		this.transformer = transformer;
+	}
+
+
+	public Message<?> handle(Message<?> message) {
 		try {
-	        Object result = this.invokeMethod(message.getPayload());
+	        Object result = this.transformer.transform(message.getPayload());
 	        return MessageBuilder.fromPayload(result).copyHeaders(message.getHeaders()).build();
         } catch (Exception e) {
         	throw new MessagingException(message, "failed to transform message payload", e);

org.springframework.integration/src/test/java/org/springframework/integration/transformer/MethodInvokingPayloadTransformerTests.java

@@ -0,0 +1,62 @@
+/*
+ * 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.transformer;
+
+import static org.junit.Assert.assertEquals;
+
+import java.util.Date;
+
+import org.junit.Test;
+
+/**
+ * @author Mark Fisher
+ */
+public class MethodInvokingPayloadTransformerTests {
+
+	@Test
+	public void testSimpleMethod() throws Exception {
+		MethodInvokingPayloadTransformer transformer = new MethodInvokingPayloadTransformer();
+		transformer.setObject(new TestBean());
+		transformer.setMethodName("exclaim");
+		assertEquals("FOO!", transformer.transform("foo"));
+	}
+
+	@Test
+	public void testTypeConversion() throws Exception {
+		MethodInvokingPayloadTransformer transformer = new MethodInvokingPayloadTransformer();
+		transformer.setObject(new TestBean());
+		transformer.setMethodName("exclaim");
+		assertEquals("123!", transformer.transform(123));
+	}
+
+	@Test(expected=NoSuchMethodException.class)
+	public void testTypeConversionFailure() throws Exception {
+		MethodInvokingPayloadTransformer transformer = new MethodInvokingPayloadTransformer();
+		transformer.setObject(new TestBean());
+		transformer.setMethodName("exclaim");
+		transformer.transform(new Date());
+	}
+
+
+	private static class TestBean {
+
+		String exclaim(String input) {
+			return input.toUpperCase() + "!";
+		}
+	}
+
+}

org.springframework.integration/src/test/java/org/springframework/integration/transformer/PayloadTransformingMessageHandlerTests.java

@@ -30,42 +30,41 @@ import org.springframework.integration.message.StringMessage;
 /**
  * @author Mark Fisher
  */
-public class PayloadTransformerAdapterTests {
+public class PayloadTransformingMessageHandlerTests {
 
 	@Test
-	public void testSimpleMethod() {
-		PayloadTransformerAdapter adapter = new PayloadTransformerAdapter();
-		adapter.setObject(new TestBean());
-		adapter.setMethodName("exclaim");
+	public void testSuccessfulTransformation() {
+		PayloadTransformingMessageHandler handler = new PayloadTransformingMessageHandler(
+				new TestPayloadTransformer());
 		Message<?> message = new StringMessage("foo");
-		Message<?> result = adapter.transform(message);
-		assertEquals("FOO!", result.getPayload());
-	}
-
-	@Test
-	public void testTypeConversion() {
-		PayloadTransformerAdapter adapter = new PayloadTransformerAdapter();
-		adapter.setObject(new TestBean());
-		adapter.setMethodName("exclaim");
-		Message<?> message = new GenericMessage<Integer>(123);
-		Message<?> result = adapter.transform(message);
-		assertEquals("123!", result.getPayload());
+		Message<?> result = handler.handle(message);
+		assertEquals(3, result.getPayload());
 	}
 
 	@Test(expected=MessagingException.class)
-	public void testTypeConversionFailure() {
-		PayloadTransformerAdapter adapter = new PayloadTransformerAdapter();
-		adapter.setObject(new TestBean());
-		adapter.setMethodName("exclaim");
+	public void testExceptionThrownByTransformer() {
+		PayloadTransformingMessageHandler handler = new PayloadTransformingMessageHandler(
+				new TestPayloadTransformer());
+		Message<?> message = new StringMessage("bad");
+		handler.handle(message);
+	}
+
+	@Test(expected=MessagingException.class)
+	public void testWrongPayloadType() {
+		PayloadTransformingMessageHandler handler = new PayloadTransformingMessageHandler(
+				new TestPayloadTransformer());
 		Message<?> message = new GenericMessage<Date>(new Date());
-		adapter.transform(message);
+		handler.handle(message);
 	}
 
 
-	private static class TestBean {
+	private static class TestPayloadTransformer implements PayloadTransformer<String, Integer> {
 
-		String exclaim(String input) {
-			return input.toUpperCase() + "!";
+		public Integer transform(String s) throws Exception {
+			if (s.equals("bad")) {
+				throw new Exception("bad input!");
+			}
+			return s.length();
 		}
 	}