Java tutorial
/* * #%L * Alfresco Repository * %% * Copyright (C) 2005 - 2016 Alfresco Software Limited * %% * This file is part of the Alfresco software. * If the software was purchased under a paid Alfresco license, the terms of * the paid license agreement will prevail. Otherwise, the software is * provided under the following open source license terms: * * Alfresco is free software: you can redistribute it and/or modify * it under the terms of the GNU Lesser General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * Alfresco is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public License * along with Alfresco. If not, see <http://www.gnu.org/licenses/>. * #L% */ package org.alfresco.repo.publishing; import java.io.IOException; import java.util.concurrent.ConcurrentHashMap; import java.util.concurrent.ConcurrentMap; import javax.xml.bind.JAXBContext; import javax.xml.bind.JAXBElement; import javax.xml.bind.JAXBException; import javax.xml.bind.MarshalException; import javax.xml.bind.Marshaller; import javax.xml.bind.PropertyException; import javax.xml.bind.UnmarshalException; import javax.xml.bind.Unmarshaller; import javax.xml.bind.annotation.XmlRootElement; import javax.xml.bind.annotation.XmlType; import javax.xml.transform.Result; import javax.xml.transform.Source; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.springframework.core.annotation.AnnotationUtils; import org.springframework.http.HttpHeaders; import org.springframework.http.MediaType; import org.springframework.http.converter.HttpMessageConversionException; import org.springframework.http.converter.HttpMessageNotReadableException; import org.springframework.http.converter.HttpMessageNotWritableException; import org.springframework.http.converter.xml.AbstractXmlHttpMessageConverter; import org.springframework.util.Assert; import org.springframework.util.ClassUtils; /** * @author Brian * @since 4.0 */ public class JaxbHttpMessageConverter extends AbstractXmlHttpMessageConverter<Object> { private static Log log = LogFactory.getLog(JaxbHttpMessageConverter.class); private JAXBContext defaultJaxbContext = null; private final ConcurrentMap<Class<?>, JAXBContext> jaxbContexts = new ConcurrentHashMap<Class<?>, JAXBContext>(); public JaxbHttpMessageConverter() { super(); } /** * Create a JAXB message converter, specifying the Java packages it should use to find JAXB classes * @param packagesToInclude A colon-separated list of package names. * @see JAXBContext#newInstance(String) */ public JaxbHttpMessageConverter(String packagesToInclude) { super(); try { defaultJaxbContext = JAXBContext.newInstance(packagesToInclude); } catch (JAXBException e) { log.error("Failed to instantiate JAXB context with supplied context path " + packagesToInclude, e); } } @Override public boolean canRead(Class<?> clazz, MediaType mediaType) { return (clazz.isAnnotationPresent(XmlRootElement.class) || clazz.isAnnotationPresent(XmlType.class)) && canRead(mediaType); } @Override public boolean canWrite(Class<?> clazz, MediaType mediaType) { return AnnotationUtils.findAnnotation(clazz, XmlRootElement.class) != null && canWrite(mediaType); } @Override protected boolean supports(Class<?> clazz) { // should not be called, since we override canRead/Write throw new UnsupportedOperationException(); } @Override protected boolean canWrite(MediaType mediaType) { return super.canWrite(mediaType) || MediaType.TEXT_XML.equals(mediaType); } @Override protected Object readFromSource(Class<?> clazz, HttpHeaders headers, Source source) throws IOException { try { Unmarshaller unmarshaller = createUnmarshaller(clazz); if (clazz.isAnnotationPresent(XmlRootElement.class)) { return unmarshaller.unmarshal(source); } else { JAXBElement<?> jaxbElement = unmarshaller.unmarshal(source, clazz); return jaxbElement.getValue(); } } catch (UnmarshalException ex) { throw new HttpMessageNotReadableException("Could not unmarshal to [" + clazz + "]: " + ex.getMessage(), ex); } catch (JAXBException ex) { throw new HttpMessageConversionException("Could not instantiate JAXBContext: " + ex.getMessage(), ex); } } @Override protected void writeToResult(Object o, HttpHeaders headers, Result result) throws IOException { try { Class<?> clazz = ClassUtils.getUserClass(o); Marshaller marshaller = createMarshaller(clazz); setCharset(headers.getContentType(), marshaller); marshaller.marshal(o, result); } catch (MarshalException ex) { throw new HttpMessageNotWritableException("Could not marshal [" + o + "]: " + ex.getMessage(), ex); } catch (JAXBException ex) { throw new HttpMessageConversionException("Could not instantiate JAXBContext: " + ex.getMessage(), ex); } } private void setCharset(MediaType contentType, Marshaller marshaller) throws PropertyException { if (contentType != null && contentType.getCharSet() != null) { marshaller.setProperty(Marshaller.JAXB_ENCODING, contentType.getCharSet().name()); } } /** * Creates a new {@link Marshaller} for the given class. * * @param clazz * the class to create the marshaller for * @return the {@code Marshaller} * @throws HttpMessageConversionException * in case of JAXB errors */ protected final Marshaller createMarshaller(Class<?> clazz) { try { JAXBContext jaxbContext = getJaxbContext(clazz); return jaxbContext.createMarshaller(); } catch (JAXBException ex) { throw new HttpMessageConversionException( "Could not create Marshaller for class [" + clazz + "]: " + ex.getMessage(), ex); } } /** * Creates a new {@link Unmarshaller} for the given class. * * @param clazz * the class to create the unmarshaller for * @return the {@code Unmarshaller} * @throws HttpMessageConversionException * in case of JAXB errors */ protected final Unmarshaller createUnmarshaller(Class<?> clazz) throws JAXBException { try { JAXBContext jaxbContext = getJaxbContext(clazz); return jaxbContext.createUnmarshaller(); } catch (JAXBException ex) { throw new HttpMessageConversionException( "Could not create Unmarshaller for class [" + clazz + "]: " + ex.getMessage(), ex); } } /** * Returns a {@link JAXBContext} for the given class. * * @param clazz * the class to return the context for * @return the {@code JAXBContext} * @throws HttpMessageConversionException * in case of JAXB errors */ protected final JAXBContext getJaxbContext(Class<?> clazz) { Assert.notNull(clazz, "'clazz' must not be null"); JAXBContext result = null; if (defaultJaxbContext != null) { result = defaultJaxbContext; } else { result = jaxbContexts.get(clazz); if (result == null) { try { result = JAXBContext.newInstance(clazz); jaxbContexts.putIfAbsent(clazz, result); } catch (JAXBException ex) { throw new HttpMessageConversionException( "Could not instantiate JAXBContext for class [" + clazz + "]: " + ex.getMessage(), ex); } } } return result; } }