| /* |
| * 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 sample; |
| |
| import java.io.StringWriter; |
| import java.util.ArrayList; |
| import java.util.Iterator; |
| import java.util.List; |
| |
| import javax.xml.parsers.DocumentBuilder; |
| import javax.xml.parsers.DocumentBuilderFactory; |
| import javax.xml.parsers.ParserConfigurationException; |
| 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.xpath.XPath; |
| import javax.xml.xpath.XPathConstants; |
| import javax.xml.xpath.XPathExpressionException; |
| import javax.xml.xpath.XPathFactory; |
| |
| import org.w3c.dom.Document; |
| import org.w3c.dom.Element; |
| import org.w3c.dom.Node; |
| import org.w3c.dom.NodeList; |
| |
| /** |
| * Just for fun, a little bit of magic code and utility functions to help work with XML DOM. |
| */ |
| class Xutil { |
| interface NodeBuilder { |
| Node build(Document doc); |
| } |
| |
| /** |
| * Convert a name and a list of children to a document element. |
| */ |
| static Element xdom(String ns, String name, final NodeBuilder... nodes) { |
| return (Element)elem(ns, name, nodes).build(db.newDocument()); |
| } |
| |
| /** |
| * Convert a name and children to an element. |
| */ |
| static NodeBuilder elem(final String uri, final String n, final NodeBuilder... nodes) { |
| return new NodeBuilder() { |
| public Node build(Document doc) { |
| final Element e = doc.createElementNS(uri, n); |
| for(final NodeBuilder n: nodes) |
| e.appendChild(n.build(doc)); |
| return e; |
| } |
| }; |
| } |
| |
| static NodeBuilder elem(final String n, final NodeBuilder... nodes) { |
| return elem(null, n, nodes); |
| } |
| |
| /** |
| * Convert a string to a text element. |
| */ |
| static NodeBuilder text(final String t) { |
| return new NodeBuilder() { |
| public Node build(final Document doc) { |
| return doc.createTextNode(t); |
| } |
| }; |
| } |
| |
| private final static DocumentBuilder db = db(); |
| |
| private static DocumentBuilder db() { |
| try { |
| return DocumentBuilderFactory.newInstance().newDocumentBuilder(); |
| } catch(ParserConfigurationException e) { |
| throw new RuntimeException(e); |
| } |
| } |
| |
| /** |
| * Convert an element to XML. |
| */ |
| static TransformerFactory trf = TransformerFactory.newInstance(); |
| |
| static String xml(final Node node) { |
| try { |
| final StreamResult r = new StreamResult(new StringWriter()); |
| trf.newTransformer().transform(new DOMSource(node), r); |
| return r.getWriter().toString(); |
| } catch(TransformerException e) { |
| throw new RuntimeException(e); |
| } |
| } |
| |
| /** |
| * Evaluate an xpath expression. |
| */ |
| private static XPathFactory xpf = XPathFactory.newInstance(); |
| |
| static String xpath(final String expr, final Node node) { |
| final XPath xp = xpf.newXPath(); |
| try { |
| return (String)xp.evaluate(expr, node, XPathConstants.STRING); |
| } catch(XPathExpressionException e) { |
| throw new RuntimeException(e); |
| } |
| } |
| |
| /** |
| * A pure Java FP-style alternative to xpath for DOM. |
| */ |
| interface Mapper<T> { |
| T map(final Element e); |
| } |
| |
| static Mapper<Element> identity = new Mapper<Element>() { |
| public Element map(Element e) { |
| return e; |
| }; |
| }; |
| |
| interface Reducer<T> { |
| T reduce(final T accum, final Element e); |
| } |
| |
| static Reducer<String> print = new Reducer<String>() { |
| public String reduce(String accum, Element e) { |
| return accum + e.getTextContent(); |
| } |
| }; |
| |
| /** |
| * Apply a mapper to a list of elements. |
| */ |
| static <T> List<T> xmap(final Mapper<T> f, final Iterable<Element> l) { |
| final List<T> v = new ArrayList<T>(); |
| for(Element e: l) |
| v.add(f.map(e)); |
| return v; |
| } |
| |
| /** |
| * Apply a filter to a list of elements. |
| */ |
| static List<Element> xfilter(final Mapper<Boolean> f, final Iterable<Element> l) { |
| final List<Element> v = new ArrayList<Element>(); |
| for(Element e: l) |
| if(f.map(e)) |
| v.add(e); |
| return v; |
| } |
| |
| /** |
| * Perform a reduction over a list of elements. |
| */ |
| static <T> T xreduce(final Reducer<T> f, final T initial, final Iterable<Element> l) { |
| T accum = initial; |
| for(Element e: l) |
| accum = f.reduce(accum, e); |
| return accum; |
| } |
| |
| /** |
| * Return a filter that selects elements by name. |
| */ |
| static Mapper<Boolean> select(final String name) { |
| return new Mapper<Boolean>() { |
| public Boolean map(Element e) { |
| return name.equals(e.getLocalName()); |
| } |
| }; |
| } |
| |
| /** |
| * Return the child elements of a node. |
| */ |
| static Iterable<Element> elems(final Node parent) { |
| final List<Element> l = new ArrayList<Element>(); |
| for (Node n: children(parent)) |
| if (n instanceof Element) |
| l.add((Element)n); |
| return l; |
| } |
| |
| /** |
| * An iterable over the children of a node. |
| */ |
| private static Iterable<Node> children(Node parent) { |
| final NodeList l = parent.getChildNodes(); |
| final int n = l.getLength(); |
| return new Iterable<Node>() { |
| public Iterator<Node> iterator() { |
| return new Iterator<Node>() { |
| int i = 0; |
| public boolean hasNext() { |
| return i < n; |
| } |
| public Node next() { |
| return l.item(i++); |
| } |
| public void remove() { |
| } |
| }; |
| } |
| }; |
| } |
| } |