Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance * with the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, * software distributed under the License is distributed on an * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY * KIND, either express or implied. See the License for the * specific language governing permissions and limitations * under the License. */ package org.apache.hise.utils; import java.io.ByteArrayInputStream; import java.io.IOException; import java.util.List; import java.util.Map; import javax.xml.namespace.NamespaceContext; import javax.xml.namespace.QName; import javax.xml.parsers.DocumentBuilder; import javax.xml.parsers.ParserConfigurationException; import javax.xml.xpath.XPath; import javax.xml.xpath.XPathConstants; import javax.xml.xpath.XPathExpression; import javax.xml.xpath.XPathFactory; import javax.xml.xpath.XPathFunction; import javax.xml.xpath.XPathFunctionException; import javax.xml.xpath.XPathFunctionResolver; import net.sf.saxon.dom.NodeOverNodeInfo; import net.sf.saxon.om.NodeInfo; import org.apache.commons.lang.Validate; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.hise.dao.Message; import org.w3c.dom.Document; import org.w3c.dom.Node; import org.w3c.dom.NodeList; import org.xml.sax.SAXException; public class TaskXmlUtils { private final Log __log = LogFactory.getLog(TaskXmlUtils.class); private XPathFactory xPathFactory = null; private NamespaceContext namespaceContext; private Map<String, Message> input; private Map<String, Message> output; public TaskXmlUtils(NamespaceContext namespaceContext, Map<String, Message> input, Map<String, Message> output) { super(); this.xPathFactory = DOMUtils.getXPathFactory(); this.namespaceContext = namespaceContext; this.input = input; this.output = output; } /** * Creates {@link XPath} aware of request namespaces. */ synchronized XPath createXPathInstance() { XPath xpath = this.xPathFactory.newXPath(); xpath.setNamespaceContext(this.namespaceContext); xpath.setXPathFunctionResolver(new XPathFunctionResolver() { public XPathFunction resolveFunction(QName functionName, int arity) { if (functionName == null) { throw new NullPointerException("The function name cannot be null."); } if (functionName.equals(new QName("http://www.example.org/WS-HT", "getInput", "htd"))) { return new GetXPathFunction(input); } if (functionName.equals(new QName("http://www.example.org/WS-HT", "getOutput", "htd"))) { return new GetXPathFunction(output); } return null; } }); return xpath; } /** * Evaluates XPath expression in context of the Task. Expression can contain * XPath Extension functions as defined by WS-HumanTask v1. Following * XPath functions are implemented: * <ul> * <li> {@link GetInputXPathFunction} </li> * <li> {@link GetOutputXPathFunction} </li> * </ul> * @param xPathString The XPath 1.0 expression. * @param returnType The desired return type. See {@link XPathConstants}. * @return The result of evaluating the <code>XPath</code> function as an <code>Object</code>. */ public Object evaluateXPath(String xPathString, QName returnType) { Validate.notNull(xPathString); Validate.notNull(returnType); Object o = null; XPath xpath = createXPathInstance(); try { //TODO create empty document only once DocumentBuilder builder = DOMUtils.getDocumentBuilderFactory().newDocumentBuilder(); Document emptyDocument; emptyDocument = builder.parse(new ByteArrayInputStream("<empty/>".getBytes())); XPathExpression expr = xpath.compile(xPathString); o = expr.evaluate(emptyDocument, returnType); __log.debug("evaluated " + o); if (o instanceof NodeInfo) { NodeInfo o2 = (NodeInfo) o; Node o3 = NodeOverNodeInfo.wrap(o2); __log.debug("returned " + DOMUtils.domToString(o3)); return o3; } else { return o; } } catch (Exception e) { __log.error("Error evaluating XPath: " + xPathString, e); throw new RuntimeException(e); } } /** * Implements getInput {@link XPathFunction} - get the data for the part of the task's input message. * @author Witek Woejszo */ private static class GetXPathFunction implements XPathFunction { private final Log log = LogFactory.getLog(GetXPathFunction.class); private Map<String, Message> data; public GetXPathFunction(Map<String, Message> data) { this.data = data; } /** * <p>Evaluate the function with the specified arguments.</p> * @see XPathFunction#evaluate(List) * @param args The arguments, <code>null</code> is a valid value. * @return The result of evaluating the <code>XPath</code> function as an <code>Object</code>. * @throws XPathFunctionException If <code>args</code> cannot be evaluated with this <code>XPath</code> function. */ public Object evaluate(List args) throws XPathFunctionException { String partName = (String) args.get(0); Message message = data.get(partName); Document document = null; if (message == null) { throw new XPathFunctionException("Task's input does not contain partName: " + args.get(0)); } // try { // // document = message.getDomDocument(); // // } catch (ParserConfigurationException e) { // // throw new XPathFunctionException(e); // } catch (SAXException e) { // // throw new XPathFunctionException(e); // } catch (IOException e) { // // throw new XPathFunctionException(e); // } if (document == null) return null; NodeList l = document.getElementsByTagName(partName); Validate.isTrue(l.getLength() == 1, "Exactly one part must exist."); return l.item(0); } } }