Java tutorial
/* =================================================================== * XmlSupport.java * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License as * published by the Free Software Foundation; either version 2 of * the License, or (at your option) any later version. * * This program 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 * General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA * 02111-1307 USA * =================================================================== */ package net.solarnetwork.support; import java.beans.PropertyDescriptor; import java.beans.PropertyEditor; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.util.LinkedHashMap; import java.util.Map; import javax.xml.namespace.NamespaceContext; import javax.xml.parsers.DocumentBuilderFactory; import javax.xml.parsers.ParserConfigurationException; import javax.xml.transform.OutputKeys; import javax.xml.transform.Source; import javax.xml.transform.Templates; import javax.xml.transform.Transformer; import javax.xml.transform.TransformerConfigurationException; import javax.xml.transform.TransformerException; import javax.xml.transform.TransformerFactory; import javax.xml.transform.dom.DOMSource; import javax.xml.transform.stream.StreamResult; import javax.xml.transform.stream.StreamSource; import javax.xml.xpath.XPath; import javax.xml.xpath.XPathConstants; import javax.xml.xpath.XPathExpression; import javax.xml.xpath.XPathExpressionException; import javax.xml.xpath.XPathFactory; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.beans.BeanWrapper; import org.springframework.beans.PropertyAccessor; import org.springframework.core.io.Resource; import org.w3c.dom.Document; import org.w3c.dom.Element; import org.w3c.dom.Node; /** * A class to support services that use XML. * * <p> * The configurable properties of this class are: * </p> * * <dl class="class-properties"> * <dt>docBuilderFactory</dt> * <dd>A JAXP {@link DocumentBuilderFactory} to use. If not configured, the * {@link DocumentBuilderFactory#newInstance()} method will be used to create a * default one.</p> * * <dt>transformerFactory</dt> * <dd>A JAXP {@link TransformerFactory} for handling XSLT transformations with. * If not configured, the {@link TransformerFactory#newInstance()} method will * be used to create a default one.</p> * * <dt>xpathFactory</dt> * <dd>A JAXP {@link XPathFactory} for handling XPath operations with. If not * configured the {@link XPathFactory#newInstance()} method will be used to * create a default one.</dd> * * <dt>nsContext</dt> * <dd>An optional {@link NamespaceContext} to use for proper XML namespace * handling in some contexts, such as XPath.</dd> * </dl> * * @author matt * @version 1.1 */ public class XmlSupport { protected final Logger log = LoggerFactory.getLogger(getClass()); private NamespaceContext nsContext = null; private DocumentBuilderFactory docBuilderFactory = null; private XPathFactory xpathFactory = null; private TransformerFactory transformerFactory = null; /** * Compile XPathExpression mappings from String XPath expressions. * * @param xpathMap * the XPath string expressions * @return the XPathExperssion mapping */ public Map<String, XPathExpression> getXPathExpressionMap(Map<String, String> xpathMap) { Map<String, XPathExpression> datumXPathMap = new LinkedHashMap<String, XPathExpression>(); for (Map.Entry<String, String> me : xpathMap.entrySet()) { try { datumXPathMap.put(me.getKey(), getXPathExpression(me.getValue())); } catch (XPathExpressionException e) { throw new RuntimeException(e); } } return datumXPathMap; } /** * Compile a single XPathExpression from a String XPath expression. The * {@link #getNsContext()} will be configured on the resulting * XPathExpression, if available. * * @param xpath * the XPath to compile * @return the compiled XPath * @throws XPathExpressionException * if the XPath cannot be compiled */ public XPathExpression getXPathExpression(String xpath) throws XPathExpressionException { XPath xp = getXpathFactory().newXPath(); if (getNsContext() != null) { xp.setNamespaceContext(getNsContext()); } return xp.compile(xpath); } /** * Get an XSLT Templates object from an XSLT Resource. * * @param resource * the XSLT Resource to load * @return the compiled Templates */ public Templates getTemplates(Resource resource) { TransformerFactory tf = TransformerFactory.newInstance(); try { return tf.newTemplates(new StreamSource(resource.getInputStream())); } catch (TransformerConfigurationException e) { throw new RuntimeException("Unable to load XSLT from resource [" + resource + ']'); } catch (IOException e) { throw new RuntimeException("Unable to load XSLT from resource [" + resource + ']'); } } /** * Turn an object into a simple XML Document, supporting custom property * editors. * * <p> * The returned XML will be a document with a single element with all * JavaBean properties turned into attributes. For example: * <p> * * <pre> * <powerDatum * id="123" * pvVolts="123.123" * ... /> * </pre> * * <p> * {@link PropertyEditor} instances can be registered with the supplied * {@link BeanWrapper} for custom handling of properties, e.g. dates. * </p> * * @param bean * the object to turn into XML * @param elementName * the name of the XML element * @return the element, as an XML DOM Document */ public Document getDocument(BeanWrapper bean, String elementName) { Document dom = null; try { dom = getDocBuilderFactory().newDocumentBuilder().newDocument(); dom.appendChild(getElement(bean, elementName, dom)); } catch (ParserConfigurationException e) { throw new RuntimeException(e); } return dom; } /** * Turn an object into a simple XML Element, supporting custom property * editors. * * <p> * The returned XML will be a single element with all JavaBean properties * turned into attributes and the element named after the bean object's * class name. For example: * <p> * * <pre> * <PowerDatum * id="123" * pvVolts="123.123" * ... /> * </pre> * * <p> * {@link PropertyEditor} instances can be registered with the supplied * {@link BeanWrapper} for custom handling of properties, e.g. dates. * </p> * * @param bean * the object to turn into XML * @return the element, as an XML DOM Document */ public Element getElement(BeanWrapper bean, Document dom) { String elementName = bean.getWrappedInstance().getClass().getSimpleName(); return getElement(bean, elementName, dom); } /** * Turn an object into a simple XML Element, supporting custom property * editors. * * <p> * The returned XML will be a single element with all JavaBean properties * turned into attributes. For example: * <p> * * <pre> * <powerDatum * id="123" * pvVolts="123.123" * ... /> * </pre> * * <p> * {@link PropertyEditor} instances can be registered with the supplied * {@link BeanWrapper} for custom handling of properties, e.g. dates. * </p> * * @param bean * the object to turn into XML * @param elementName * the name of the XML element * @return the element, as an XML DOM Element */ public Element getElement(BeanWrapper bean, String elementName, Document dom) { PropertyDescriptor[] props = bean.getPropertyDescriptors(); Element root = null; root = dom.createElement(elementName); for (int i = 0; i < props.length; i++) { PropertyDescriptor prop = props[i]; if (prop.getReadMethod() == null) { continue; } String propName = prop.getName(); if ("class".equals(propName)) { continue; } Object propValue = null; PropertyEditor editor = bean.findCustomEditor(prop.getPropertyType(), prop.getName()); if (editor != null) { editor.setValue(bean.getPropertyValue(propName)); propValue = editor.getAsText(); } else { propValue = bean.getPropertyValue(propName); } if (propValue == null) { continue; } if (log.isTraceEnabled()) { log.trace("attribute name: " + propName + " attribute value: " + propValue); } root.setAttribute(propName, propValue.toString()); } return root; } /** * Turn an object into a simple XML Document, supporting custom property * editors. * * <p> * The returned XML will be a single element with all JavaBean properties * turned into attributed. For example: * <p> * * <pre> * <powerDatum * id="123" * pvVolts="123.123" * ... /> * </pre> * * @param bean * the object to turn into XML * @param elementName * the name of the XML element * @return the element, as XSLT Source * @see #getDocument(BeanWrapper, String) */ public Source getSource(BeanWrapper bean, String elementName) { Document dom = getDocument(bean, elementName); return getSource(dom); } /** * Turn a Document into a Source. * * <p> * This method will log the XML document at the FINEST level. * </p> * * @param dom * the Document to turn into XSLT source * @return the document, as XSLT Source */ public Source getSource(Document dom) { DOMSource result = new DOMSource(dom); if (log.isDebugEnabled()) { log.debug("XML: " + getXmlAsString(result, true)); } return result; } /** * Turn an XML Source into a String. * * @param source * the XML Source * @param indent * if <em>true</em> then indent the result * @return the XML, as a String */ public String getXmlAsString(Source source, boolean indent) { ByteArrayOutputStream byos = new ByteArrayOutputStream(); try { Transformer xform = getTransformerFactory().newTransformer(); if (indent) { xform.setOutputProperty(OutputKeys.INDENT, "yes"); xform.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2"); } xform.transform(source, new StreamResult(byos)); } catch (TransformerConfigurationException e) { throw new RuntimeException(e); } catch (TransformerException e) { throw new RuntimeException(e); } return byos.toString(); } /** * Populate JavaBean properties via XPath extraction. * * @param obj * the object to set properties on, or a BeanWrapper * @param xml * the XML * @param xpathMap * the mapping of JavaBean property names to XPaths */ public void extractBeanDataFromXml(PropertyAccessor bean, Node xml, Map<String, XPathExpression> xpathMap) { for (Map.Entry<String, XPathExpression> me : xpathMap.entrySet()) { String val = extractStringFromXml(xml, me.getValue()); if (val != null && !"".equals(val)) { bean.setPropertyValue(me.getKey(), val); } } } /** * Extract a String value via an XPath expression. * * @param xml * the XML * @param xpath * the XPath expression * @return the String */ public String extractStringFromXml(Node xml, XPathExpression xpath) { try { return (String) xpath.evaluate(xml, XPathConstants.STRING); } catch (XPathExpressionException e) { throw new RuntimeException("Unable to extract string from XPath [" + xpath.toString() + "]", e); } } public NamespaceContext getNsContext() { return nsContext; } public void setNsContext(NamespaceContext nsContext) { this.nsContext = nsContext; } public DocumentBuilderFactory getDocBuilderFactory() { DocumentBuilderFactory result = this.docBuilderFactory; if (result == null) { result = DocumentBuilderFactory.newInstance(); result.setNamespaceAware(true); this.docBuilderFactory = result; } return result; } public void setDocBuilderFactory(DocumentBuilderFactory docBuilderFactory) { this.docBuilderFactory = docBuilderFactory; } public XPathFactory getXpathFactory() { XPathFactory result = this.xpathFactory; if (result == null) { // work around Oracle JDK issues loading XPathFactory, see // https://java.net/projects/glassfish/lists/users/archive/2012-02/message/371 final ClassLoader origClassLoader = Thread.currentThread().getContextClassLoader(); Thread.currentThread().setContextClassLoader(XPathFactory.class.getClassLoader()); try { result = XPathFactory.newInstance(); this.xpathFactory = result; } finally { Thread.currentThread().setContextClassLoader(origClassLoader); } } return result; } public void setXpathFactory(XPathFactory xpathFactory) { this.xpathFactory = xpathFactory; } public TransformerFactory getTransformerFactory() { TransformerFactory result = this.transformerFactory; if (result == null) { // work around Oracle JDK issues loading XPathFactory, see // https://java.net/projects/glassfish/lists/users/archive/2012-02/message/371 final ClassLoader origClassLoader = Thread.currentThread().getContextClassLoader(); Thread.currentThread().setContextClassLoader(XPathFactory.class.getClassLoader()); try { result = TransformerFactory.newInstance(); this.transformerFactory = result; } finally { Thread.currentThread().setContextClassLoader(origClassLoader); } } return result; } public void setTransformerFactory(TransformerFactory transformerFactory) { this.transformerFactory = transformerFactory; } }