MessageHeaders no removes any non-serializable values from its map upon serialization. A warn-level notification will be logged.

org.springframework.integration/src/main/java/org/springframework/integration/core/MessageHeaders.java

@@ -16,14 +16,22 @@
 
 package org.springframework.integration.core;
 
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
 import java.io.Serializable;
+import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.UUID;
 
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
 /**
  * The headers for a {@link Message}.
  * 
@@ -32,6 +40,8 @@ import java.util.UUID;
  */
 public final class MessageHeaders implements Map<String, Object>, Serializable {
 
+	private static final Log logger = LogFactory.getLog(MessageHeaders.class);
+
 	private static final String PREFIX = "spring.integration.";
 
 	public static final String ID = PREFIX + "id";
@@ -110,10 +120,8 @@ public final class MessageHeaders implements Map<String, Object>, Serializable {
 			return null;
 		}
 		if (!type.isAssignableFrom(value.getClass())) {
-			throw new IllegalArgumentException(
-					"Incorrect type specified for header '" + key
-							+ "'. Expected [" + type + "] but actual type is ["
-							+ value.getClass() + "]");
+			throw new IllegalArgumentException("Incorrect type specified for header '" + key
+					+ "'. Expected [" + type + "] but actual type is [" + value.getClass() + "]");
 		}
 		return (T) value;
 	}
@@ -193,4 +201,28 @@ public final class MessageHeaders implements Map<String, Object>, Serializable {
 		throw new UnsupportedOperationException("MessageHeaders is immutable.");
 	}
 
+	/*
+	 * Serialization methods
+	 */
+
+	private void writeObject(ObjectOutputStream out) throws IOException {
+		List<String> keysToRemove = new ArrayList<String>();
+		for (Map.Entry<String, Object> entry : this.headers.entrySet()) {
+			if (!(entry.getValue() instanceof Serializable)) {
+				keysToRemove.add(entry.getKey());
+			}
+		}
+		for (String key : keysToRemove) {
+			if (logger.isWarnEnabled()) {
+				logger.warn("removing non-serializable header: " + key);
+			}
+			this.headers.remove(key);
+		}
+		out.defaultWriteObject();
+	}
+
+	private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
+		in.defaultReadObject();
+	}
+
 }

org.springframework.integration/src/main/java/org/springframework/integration/message/MessageBuilder.java

@@ -51,7 +51,7 @@ public final class MessageBuilder<T> {
 		this.payload = payload;
 		this.originalMessage = originalMessage;
 		if (originalMessage != null) {
-			this.headers.putAll(originalMessage.getHeaders());
+			this.copyHeaders(originalMessage.getHeaders());
 		}
 	}
 

org.springframework.integration/src/test/java/org/springframework/integration/message/MessageHeadersTests.java

@@ -21,6 +21,10 @@ import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
 
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Set;
@@ -92,4 +96,40 @@ public class MessageHeadersTests {
 		assertTrue(keys.contains("key2"));
 	}
 
+	@Test
+	public void serializeWithAllSerializableHeaders() throws Exception {
+		Map<String, Object> map = new HashMap<String, Object>();
+		map.put("name", "joe");
+		map.put("age", 42);
+		MessageHeaders input = new MessageHeaders(map);
+		MessageHeaders output = (MessageHeaders) serializeAndDeserialize(input);
+		assertEquals("joe", output.get("name"));
+		assertEquals(42, output.get("age"));
+	}
+
+	@Test
+	public void serializeWithNonSerializableHeader() throws Exception {
+		Object address = new Object();
+		Map<String, Object> map = new HashMap<String, Object>();
+		map.put("name", "joe");
+		map.put("address", address);
+		MessageHeaders input = new MessageHeaders(map);
+		MessageHeaders output = (MessageHeaders) serializeAndDeserialize(input);
+		assertEquals("joe", output.get("name"));
+		assertNull(output.get("address"));
+	}
+
+
+	private static Object serializeAndDeserialize(Object object) throws Exception {
+		ByteArrayOutputStream baos = new ByteArrayOutputStream();
+		ObjectOutputStream out = new ObjectOutputStream(baos);
+		out.writeObject(object);
+		out.close();
+		ByteArrayInputStream bais = new ByteArrayInputStream(baos.toByteArray());
+		ObjectInputStream in = new ObjectInputStream(bais);
+		Object result = in.readObject();
+		in.close();
+		return result;
+	}
+
 }