INT-3509 Add Convert Node & DOMSource to Document

JIRA: https://jira.spring.io/browse/INT-3509

**Cherry-pick to 3.0.x and 4.0.x**

Polishing

- Javadoc
- Refactor duplicated code

spring-integration-xml/src/main/java/org/springframework/integration/xml/DefaultXmlPayloadConverter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2010 the original author or authors.
+ * Copyright 2002-2014 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.
@@ -34,13 +34,15 @@ import org.springframework.xml.transform.StringSource;
 
 /**
  * Default implementation of {@link XmlPayloadConverter}. Supports
- * {@link Document}, {@link File} and {@link String} payloads.
- * 
+ * {@link Document}, {@link File}, {@link String}, {@link Node} and
+ * {@link DOMSource} payloads.
+ *
  * @author Jonas Partner
+ * @author Artem Bilan
  */
 public class DefaultXmlPayloadConverter implements XmlPayloadConverter {
 
-	private DocumentBuilderFactory documentBuilderFactory;
+	private final DocumentBuilderFactory documentBuilderFactory;
 
 
 	public DefaultXmlPayloadConverter() {
@@ -53,10 +55,23 @@ public class DefaultXmlPayloadConverter implements XmlPayloadConverter {
 	}
 
 
+	@Override
 	public Document convertToDocument(Object object) {
 		if (object instanceof Document) {
 			return (Document) object;
 		}
+		if (object instanceof Node) {
+			return nodeToDocument((Node) object);
+		}
+		else if (object instanceof DOMSource) {
+			Node node = ((DOMSource) object).getNode();
+			if (node instanceof Document) {
+				return (Document) node;
+			}
+			else {
+				return nodeToDocument(node);
+			}
+		}
 		if (object instanceof File) {
 			try {
 				return getDocumentBuilder().parse((File) object);
@@ -76,6 +91,13 @@ public class DefaultXmlPayloadConverter implements XmlPayloadConverter {
 		throw new MessagingException("unsupported payload type [" + object.getClass().getName() + "]");
 	}
 
+	protected Document nodeToDocument(Node node) {
+		Document document = getDocumentBuilder().newDocument();
+		document.appendChild(document.importNode(node, true));
+		return document;
+	}
+
+	@Override
 	public Node convertToNode(Object object) {
 		Node node = null;
 		if (object instanceof Node) {
@@ -90,6 +112,7 @@ public class DefaultXmlPayloadConverter implements XmlPayloadConverter {
 		return node;
 	}
 
+	@Override
 	public Source convertToSource(Object object) {
 		Source source = null;
 		if (object instanceof Source) {

spring-integration-xml/src/test/java/org/springframework/integration/xml/DefaultXmlPayloadConverterTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2014 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.
@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package org.springframework.integration.xml;
 
 import static org.junit.Assert.assertEquals;
@@ -25,22 +26,23 @@ import javax.xml.transform.Source;
 import javax.xml.transform.dom.DOMSource;
 import javax.xml.transform.sax.SAXSource;
 
-import org.junit.Assert;
-
 import org.custommonkey.xmlunit.XMLAssert;
+import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
-import org.springframework.messaging.MessagingException;
-import org.springframework.xml.transform.StringSource;
 import org.w3c.dom.Document;
 import org.w3c.dom.Node;
+import org.w3c.dom.NodeList;
 import org.xml.sax.InputSource;
 
+import org.springframework.messaging.MessagingException;
+import org.springframework.xml.transform.StringSource;
+
 /**
  *
  * @author Jonas Partner
  * @author Gunnar Hillert
- *
+ * @author Artem Bilan
  */
 public class DefaultXmlPayloadConverterTests {
 
@@ -90,7 +92,7 @@ public class DefaultXmlPayloadConverterTests {
 
 
 	@Test
-	public void testGetSourcePassingDocumet() throws Exception{
+	public void testGetSourcePassingDocument() throws Exception{
 		Source source = converter.convertToSource(testDocument);
 		assertEquals(DOMSource.class, source.getClass());
 	}
@@ -120,5 +122,25 @@ public class DefaultXmlPayloadConverterTests {
 		assertTrue("Wrong node returned", element == n);
     }
 
+	@Test
+	public void testConvertNodeToDocument() {
+		Node element = testDocument.getElementsByTagName("test").item(0);
+		Document doc = converter.convertToDocument(element);
+		NodeList childNodes = doc.getChildNodes();
+		assertEquals(1, childNodes.getLength());
+		assertEquals("test", childNodes.item(0).getNodeName());
+		assertEquals("hello", childNodes.item(0).getTextContent());
+	}
+
+	@Test
+	public void testConvertSourceToDocument() throws Exception{
+		Node element = testDocument.getElementsByTagName("test").item(0);
+		DOMSource domSource = new DOMSource(element);
+		Document doc = converter.convertToDocument(element);
+		NodeList childNodes = doc.getChildNodes();
+		assertEquals(1, childNodes.getLength());
+		assertEquals("test", childNodes.item(0).getNodeName());
+		assertEquals("hello", childNodes.item(0).getTextContent());
+	}
 
 }