ingo@100: /*
ingo@100:  * Copyright (c) 2010 by Intevation GmbH
ingo@100:  *
ingo@100:  * This program is free software under the LGPL (>=v2.1)
ingo@100:  * Read the file LGPL.txt coming with the software for details
ingo@100:  * or visit http://www.gnu.org/licenses/ if it does not exist.
ingo@100:  */
ingo@100: 
sascha@20: package de.intevation.artifactdatabase;
sascha@20: 
sascha@67: import java.io.File;
sascha@67: import java.io.IOException;
sascha@67: import java.io.OutputStream;
sascha@23: 
sascha@23: import javax.xml.namespace.NamespaceContext;
sascha@25: import javax.xml.namespace.QName;
sascha@23: 
sascha@67: import javax.xml.parsers.DocumentBuilderFactory;
sascha@67: import javax.xml.parsers.ParserConfigurationException;
sascha@67: 
sascha@67: import javax.xml.transform.Transformer;
sascha@67: import javax.xml.transform.TransformerConfigurationException;
sascha@67: import javax.xml.transform.TransformerException;
sascha@67: import javax.xml.transform.TransformerFactory;
sascha@67: import javax.xml.transform.TransformerFactoryConfigurationError;
sascha@67: 
sascha@67: import javax.xml.transform.dom.DOMSource;
sascha@67: 
sascha@67: import javax.xml.transform.stream.StreamResult;
sascha@67: 
sascha@67: import javax.xml.xpath.XPath;
sascha@67: import javax.xml.xpath.XPathConstants;
sascha@67: import javax.xml.xpath.XPathExpressionException;
sascha@67: import javax.xml.xpath.XPathFactory;
sascha@67: 
sascha@67: import org.apache.log4j.Logger;
sascha@67: 
sascha@67: import org.w3c.dom.Attr;
sascha@67: import org.w3c.dom.Document;
sascha@67: import org.w3c.dom.Element;
sascha@67: 
sascha@67: import org.xml.sax.SAXException;
sascha@62: 
sascha@20: /**
sascha@91:  * Some helper functions to ease work with XML concering namespaces, XPATH
sascha@91:  * and so on.
sascha@77:  *  @author <a href="mailto:sascha.teichmann@intevation.de">Sascha L. Teichmann</a>
sascha@20:  */
sascha@20: public final class XMLUtils
sascha@20: {
sascha@91:     /**
sascha@91:      * W3C URL of XForms
sascha@91:      */
ingo@64:     public static final String XFORM_URL    = "http://www.w3.org/2002/xforms";
sascha@91:     /**
sascha@91:      * W3C prefix of XForms
sascha@91:      */
ingo@64:     public static final String XFORM_PREFIX = "xform";
ingo@64: 
sascha@20:     private static Logger logger = Logger.getLogger(XMLUtils.class);
sascha@20: 
sascha@20:     private XMLUtils() {
sascha@20:     }
sascha@20: 
sascha@91:     /**
sascha@91:      * Helper class to generate elements and attributes with
sascha@91:      * namespaces.
sascha@91:      */
sascha@20:     public static class ElementCreator
sascha@20:     {
sascha@91:         /**
sascha@91:          * owner document of the elements to be created
sascha@91:          */
sascha@20:         protected Document document;
sascha@91:         /**
sascha@91:          * namespace to be used
sascha@91:          */
sascha@20:         protected String   ns;
sascha@91:         /**
sascha@91:          * prefix to be used
sascha@91:          */
sascha@20:         protected String   prefix;
sascha@20: 
sascha@91:         /**
sascha@91:          * Constructor to create an element/attribute creator
sascha@91:          * with a given namespace and namespace prefix using a
sascha@91:          * given owner document.
sascha@91:          * @param document The owning document
sascha@91:          * @param ns       The namespace
sascha@91:          * @param prefix   The namespace prefix
sascha@91:          */
sascha@20:         public ElementCreator(Document document, String ns, String prefix) {
sascha@20:             this.document = document;
sascha@20:             this.ns       = ns;
sascha@20:             this.prefix   = prefix;
sascha@20:         }
sascha@20: 
sascha@91:         /**
sascha@91:          * Creates a new element using the owning document with
sascha@91:          * the this creators namespace and namespace prefix.
sascha@91:          * @param name The name of the element
sascha@91:          * @return     The new element
sascha@91:          */
sascha@20:         public Element create(String name) {
sascha@20:             Element element = document.createElementNS(ns, name);
sascha@20:             element.setPrefix(prefix);
sascha@20:             return element;
sascha@20:         }
sascha@20: 
sascha@91:         /**
sascha@91:          * Adds a new attribute and its value to a given element.
sascha@91:          * It does not set the namespace prefix.
sascha@91:          * @param element The element to add the attribute to
sascha@91:          * @param name    The name of the attribute
sascha@91:          * @param value   The value of the attribute
sascha@91:          */
sascha@20:         public void addAttr(Element element, String name, String value) {
ingo@64:             addAttr(element, name, value, false);
ingo@64:         }
ingo@64: 
sascha@91:         /**
sascha@91:          * Adds a new attribute and its value to a given element.
sascha@91:          * If the namespace prefix is used is decided by the 'addPrefix' flag.
sascha@91:          * @param element The element to add the attribute to
sascha@91:          * @param name    The name of the attribute
sascha@91:          * @param value   The value of the attribute
sascha@91:          * @param addPrefix If true the creators namespace prefix is
sascha@91:          * set on the attribute.
sascha@91:          */
ingo@64:         public void addAttr(
ingo@64:             Element element,
ingo@64:             String  name,
ingo@64:             String  value,
ingo@64:             boolean addPrefix
ingo@64:         ) {
sascha@20:             Attr attr = document.createAttributeNS(ns, name);
sascha@20:             attr.setValue(value);
ingo@64: 
ingo@64:             if (addPrefix)
ingo@64:                 attr.setPrefix(prefix);
ingo@64: 
sascha@20:             element.setAttributeNode(attr);
sascha@20:         }
sascha@20:     } // class ElementCreator
sascha@20: 
sascha@91:     /**
sascha@91:      * Creates a new XML document
sascha@91:      * @return the new XML document ot null if something went wrong during
sascha@91:      * creation.
sascha@91:      */
sascha@20:     public static final Document newDocument() {
ingo@64:         DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
ingo@64:         factory.setNamespaceAware(true);
ingo@64: 
sascha@20:         try {
ingo@64:             return factory.newDocumentBuilder().newDocument();
sascha@20:         }
sascha@20:         catch (ParserConfigurationException pce) {
sascha@20:             logger.error(pce.getLocalizedMessage(), pce);
sascha@20:         }
sascha@20:         return null;
sascha@20:     }
sascha@23: 
sascha@91:     /**
sascha@91:      * Loads a XML document namespace aware from a file
sascha@91:      * @param file The file to load.
sascha@91:      * @return the XML document or null if something went wrong
sascha@91:      * during loading.
sascha@91:      */
sascha@62:     public static final Document parseDocument(File file) {
ingo@64:         DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
ingo@64:         factory.setNamespaceAware(true);
ingo@64: 
sascha@62:         try {
ingo@64:             return factory.newDocumentBuilder().parse(file);
sascha@62:         }
sascha@62:         catch (ParserConfigurationException pce) {
sascha@62:             logger.error(pce.getLocalizedMessage(), pce);
sascha@62:         }
sascha@62:         catch (SAXException se) {
sascha@62:             logger.error(se.getLocalizedMessage(), se);
sascha@62:         }
sascha@62:         catch (IOException ioe) {
sascha@62:             logger.error(ioe.getLocalizedMessage(), ioe);
sascha@62:         }
sascha@62:         return null;
sascha@62:     }
sascha@62: 
sascha@91:     /**
sascha@91:      * Creates a new XPath without a namespace context.
sascha@91:      * @return the new XPath.
sascha@91:      */
sascha@23:     public static final XPath newXPath() {
sascha@23:         return newXPath(null);
sascha@23:     }
sascha@23: 
sascha@91:     /**
sascha@91:      * Creates a new XPath with a given namespace context.
sascha@91:      * @param namespaceContext The namespace context to be used or null
sascha@91:      * if none should be used.
sascha@91:      * @return The new XPath
sascha@91:      */
sascha@23:     public static final XPath newXPath(NamespaceContext namespaceContext) {
sascha@23:         XPathFactory factory = XPathFactory.newInstance();
sascha@23:         XPath        xpath   = factory.newXPath();
sascha@23:         if (namespaceContext != null) {
sascha@23:             xpath.setNamespaceContext(namespaceContext);
sascha@23:         }
sascha@23:         return xpath;
sascha@23:     }
sascha@25: 
sascha@91:     /**
sascha@91:      * Evaluates an XPath query on a given object and returns the result
sascha@91:      * as a given type. No namespace context is used.
sascha@91:      * @param root  The object which is used as the root of the tree to
sascha@91:      * be searched in.
sascha@91:      * @param query The XPath query
sascha@91:      * @param returnTyp The type of the result.
sascha@91:      * @return The result of type 'returnTyp' or null if something
sascha@91:      * went wrong during XPath evaluation.
sascha@91:      */
sascha@94:     public static final Object xpath(
sascha@94:         Object root,
sascha@94:         String query,
sascha@94:         QName  returnTyp
sascha@94:     ) {
sascha@25:         return xpath(root, query, returnTyp, null);
sascha@25:     }
sascha@25: 
sascha@91:     /**
sascha@92:      * Evaluates an XPath query on a given object and returns the result
sascha@91:      * as a string. A given namespace context is used.
sascha@91:      * @param root  The object which is used as the root of the tree to
sascha@91:      * be searched in.
sascha@91:      * @param query The XPath query
sascha@91:      * @param namespaceContext The namespace context to be used or null
sascha@91:      * if none should be used.
sascha@91:      * @return The result of the query or null if something went wrong
sascha@91:      * during XPath evaluation.
sascha@91:      */
sascha@26:     public static final String xpathString(
sascha@26:         Object root, String query, NamespaceContext namespaceContext
sascha@26:     ) {
sascha@67:         return (String)xpath(
sascha@67:             root, query, XPathConstants.STRING, namespaceContext);
sascha@26:     }
sascha@26: 
sascha@91:     /**
sascha@91:      * Evaluates an XPath query on a given object and returns the result
sascha@91:      * as a given type. Optionally a namespace context is used.
sascha@91:      * @param root The object which is used as the root of the tree to
sascha@91:      * be searched in.
sascha@91:      * @param query The XPath query
sascha@91:      * @param returnType The type of the result.
sascha@91:      * @param namespaceContext The namespace context to be used or null
sascha@91:      * if none should be used.
sascha@91:      * @return The result of type 'returnTyp' or null if something
sascha@91:      * went wrong during XPath evaluation.
sascha@91:      */
sascha@25:     public static final Object xpath(
sascha@25:         Object           root,
sascha@25:         String           query,
sascha@25:         QName            returnType,
sascha@25:         NamespaceContext namespaceContext
sascha@25:     ) {
sascha@25:         if (root == null) {
sascha@25:             return null;
sascha@25:         }
sascha@25: 
sascha@25:         try {
sascha@25:             XPath xpath = newXPath(namespaceContext);
sascha@25:             if (xpath != null) {
sascha@25:                 return xpath.evaluate(query, root, returnType);
sascha@25:             }
sascha@25:         }
sascha@25:         catch (XPathExpressionException xpee) {
sascha@25:             logger.error(xpee.getLocalizedMessage(), xpee);
sascha@47:         }
sascha@25: 
sascha@25:         return null;
sascha@25:     }
sascha@67: 
sascha@91:     /**
sascha@91:      * Streams out an XML document to a given output stream.
sascha@91:      * @param document The document to be streamed out.
sascha@91:      * @param out      The output stream to be used.
sascha@91:      * @return true if operation succeeded else false.
sascha@91:      */
sascha@67:     public static boolean toStream(Document document, OutputStream out) {
sascha@67:         try {
sascha@67:             Transformer transformer =
sascha@67:                 TransformerFactory.newInstance().newTransformer();
sascha@67:             DOMSource    source = new DOMSource(document);
sascha@67:             StreamResult result = new StreamResult(out);
sascha@67:             transformer.transform(source, result);
sascha@67:             return true;
sascha@67:         }
sascha@67:         catch (TransformerConfigurationException tce) {
sascha@67:             logger.error(tce.getLocalizedMessage(), tce);
sascha@67:         }
sascha@67:         catch (TransformerFactoryConfigurationError tfce) {
sascha@67:             logger.error(tfce.getLocalizedMessage(), tfce);
sascha@67:         }
sascha@67:         catch (TransformerException te) {
sascha@67:             logger.error(te.getLocalizedMessage(), te);
sascha@67:         }
sascha@67: 
sascha@67:         return false;
sascha@67:     }
sascha@20: }
sascha@91: // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :