SPR-5745 - Support lazy initialization within Jaxb2 OXM classes

Author: poutsma

org.springframework.oxm/src/main/java/org/springframework/oxm/jaxb/Jaxb2Marshaller.java

@@ -140,6 +140,8 @@ public class Jaxb2Marshaller implements MimeMarshaller, MimeUnmarshaller, BeanCl
 
 	private Schema schema;
 
+	private boolean lazyInit = false;
+
 
 	/**
 	 * Set a JAXB context path.
@@ -259,33 +261,55 @@ public void setMtomEnabled(boolean mtomEnabled) {
 		this.mtomEnabled = mtomEnabled;
 	}
 
+	/**
+	 * Set whether to lazily initialize the {@link JAXBContext} for this marshaller.
+	 * Default is {@code false} to initialize on startup; can be switched to
+	 * {@code true}.
+	 * <p>Early initialization just applies if <code>afterPropertiesSet()</code> is called.
+	 * @see #afterPropertiesSet()
+	 */
+	public void setLazyInit(boolean lazyInit) {
+		this.lazyInit = lazyInit;
+	}
+
+
 	public void setBeanClassLoader(ClassLoader classLoader) {
 		this.beanClassLoader = classLoader;
 	}
 
 
 	public final void afterPropertiesSet() throws Exception {
-		this.jaxbContext = createJaxbContext();
-		if (!ObjectUtils.isEmpty(this.schemaResources)) {
-			this.schema = loadSchema(this.schemaResources, this.schemaLanguage);
-		}
-	}
-
-	protected JAXBContext createJaxbContext() throws Exception {
 		if (StringUtils.hasLength(this.contextPath) && !ObjectUtils.isEmpty(this.classesToBeBound)) {
 			throw new IllegalArgumentException("Specify either 'contextPath' or 'classesToBeBound property'; not both");
 		}
-		if (StringUtils.hasLength(this.contextPath)) {
-			return createJaxbContextFromContextPath();
+		else if (!StringUtils.hasLength(this.contextPath) && ObjectUtils.isEmpty(this.classesToBeBound)) {
+			throw new IllegalArgumentException("Setting either 'contextPath' or 'classesToBeBound' is required");
 		}
-		else if (!ObjectUtils.isEmpty(this.classesToBeBound)) {
-			return createJaxbContextFromClasses();
+		if (!lazyInit) {
+			getJaxbContext();
 		}
-		else {
-			throw new IllegalArgumentException("setting either contextPath or classesToBeBound is required");
+		if (!ObjectUtils.isEmpty(this.schemaResources)) {
+			this.schema = loadSchema(this.schemaResources, this.schemaLanguage);
 		}
 	}
 
+	protected synchronized JAXBContext getJaxbContext() {
+		if (this.jaxbContext == null) {
+			try {
+				if (StringUtils.hasLength(this.contextPath)) {
+					this.jaxbContext = createJaxbContextFromContextPath();
+				}
+				else if (!ObjectUtils.isEmpty(this.classesToBeBound)) {
+					this.jaxbContext = createJaxbContextFromClasses();
+				}
+			}
+			catch (JAXBException ex) {
+				throw convertJaxbException(ex);
+			}
+		}
+		return jaxbContext;
+	}
+
 	private JAXBContext createJaxbContextFromContextPath() throws JAXBException {
 		if (logger.isInfoEnabled()) {
 			logger.info("Creating JAXBContext with context path [" + this.contextPath + "]");
@@ -364,7 +388,6 @@ else if (!ObjectUtils.isEmpty(this.classesToBeBound)) {
 		return false;
 	}
 
-
 	// Marshalling
 
 	public void marshal(Object graph, Result result) throws XmlMappingException {
@@ -410,7 +433,7 @@ private void marshalStaxResult(Marshaller jaxbMarshaller, Object graph, Result s
 	 */
 	protected Marshaller createMarshaller() {
 		try {
-			Marshaller marshaller = this.jaxbContext.createMarshaller();
+			Marshaller marshaller = getJaxbContext().createMarshaller();
 			initJaxbMarshaller(marshaller);
 			return marshaller;
 		}
@@ -495,7 +518,7 @@ private Object unmarshalStaxSource(Unmarshaller jaxbUnmarshaller, Source staxSou
 	 */
 	protected Unmarshaller createUnmarshaller() {
 		try {
-			Unmarshaller unmarshaller = this.jaxbContext.createUnmarshaller();
+			Unmarshaller unmarshaller = getJaxbContext().createUnmarshaller();
 			initJaxbUnmarshaller(unmarshaller);
 			return unmarshaller;
 		}
@@ -557,7 +580,6 @@ else if (ex instanceof UnmarshalException) {
 		}
 	}
 
-
 	private static class Jaxb2AttachmentMarshaller extends AttachmentMarshaller {
 
 		private final MimeContainer mimeContainer;

org.springframework.oxm/src/test/java/org/springframework/oxm/jaxb/Jaxb2MarshallerTests.java

@@ -21,13 +21,13 @@
 import java.util.Collections;
 import javax.activation.DataHandler;
 import javax.activation.FileDataSource;
-import javax.xml.bind.JAXBException;
 import javax.xml.transform.Result;
 import javax.xml.transform.sax.SAXResult;
 import javax.xml.transform.stream.StreamResult;
 
+import static org.custommonkey.xmlunit.XMLAssert.*;
 import static org.easymock.EasyMock.*;
-import static org.junit.Assert.*;
+import static org.junit.Assert.assertTrue;
 import org.junit.Test;
 import org.xml.sax.Attributes;
 import org.xml.sax.ContentHandler;
@@ -37,6 +37,7 @@
 import org.springframework.core.io.Resource;
 import org.springframework.oxm.AbstractMarshallerTests;
 import org.springframework.oxm.Marshaller;
+import org.springframework.oxm.UncategorizedMappingException;
 import org.springframework.oxm.XmlMappingException;
 import org.springframework.oxm.jaxb.test.FlightType;
 import org.springframework.oxm.jaxb.test.Flights;
@@ -94,6 +95,18 @@ public void marshalSAXResult() throws Exception {
 		verify(handlerMock);
 	}
 
+	@Test
+	public void laxyInit() throws Exception {
+		marshaller = new Jaxb2Marshaller();
+		marshaller.setContextPath(CONTEXT_PATH);
+		marshaller.setLazyInit(true);
+		marshaller.afterPropertiesSet();
+		StringWriter writer = new StringWriter();
+		StreamResult result = new StreamResult(writer);
+		marshaller.marshal(flights, result);
+		assertXMLEqual("Marshaller writes invalid StreamResult", EXPECTED_STRING, writer.toString());
+	}
+
 	@Test
 	public void properties() throws Exception {
 		Jaxb2Marshaller marshaller = new Jaxb2Marshaller();
@@ -110,7 +123,7 @@ public void noContextPathOrClassesToBeBound() throws Exception {
 		marshaller.afterPropertiesSet();
 	}
 
-	@Test(expected = JAXBException.class)
+	@Test(expected = UncategorizedMappingException.class)
 	public void testInvalidContextPath() throws Exception {
 		Jaxb2Marshaller marshaller = new Jaxb2Marshaller();
 		marshaller.setContextPath("ab");