Java tutorial
//package com.java2s; /*--------------------------------------------------------------- * Copyright 2005 by the Radiological Society of North America * * This source software is released under the terms of the * RSNA Public License (http://mirc.rsna.org/rsnapubliclicense) *----------------------------------------------------------------*/ import org.w3c.dom.Document; import org.w3c.dom.Element; import org.w3c.dom.Node; import org.w3c.dom.NodeList; public class Main { /** * Get the value of a node specified by a starting node and a * path string. If the starting node is a Document, use the * document element as the starting point. * <ul> * <li>A path to an element has the form: elem1/.../elemN * <li>A path to an attribute has the form: elem1/.../elemN@attr * </ul> * The value of an element node is the sum of all the element's * first generation child text nodes. Note that this is not what you * would get from a mixed element in an XSL program. * @param node the top of the tree to search. * @param path the path from the top of the tree to the desired node. * @return the value of the first node matching the path, or the * empty string if no node exists at the path location or if the * starting node is not an element. */ public static String getValueViaPath(Node node, String path) { if (node instanceof Document) node = ((Document) node).getDocumentElement(); if (!(node instanceof Element)) return ""; path = path.trim(); int kAtsign = path.indexOf("@"); //If the target is an element, get the element's value. if (kAtsign == -1) { Element target = getElementViaPath(node, path); if (target == null) return ""; return target.getTextContent(); } //The target is an attribute; first find the element. String subpath = path.substring(0, kAtsign); Element target = getElementViaPath(node, subpath); if (target == null) return null; String name = path.substring(kAtsign + 1); return target.getAttribute(name); } /** * Get an element specified by a starting node and a path string. * If the starting node is a Document, use the document element * as the starting point. * <ul><li>A path to an element has the form: elem1/.../elemN</ul> * @param node the top of the tree to search. * @param path the path from the top of the tree to the desired element. * @return the first element matching the path, or null if no element * exists at the path location or if the starting node is not an element. */ public static Element getElementViaPath(Node node, String path) { if (node instanceof Document) node = ((Document) node).getDocumentElement(); if (!(node instanceof Element)) return null; int k = path.indexOf("/"); String firstPathElement = path; if (k > 0) firstPathElement = path.substring(0, k); if (node.getNodeName().equals(firstPathElement)) { if (k < 0) return (Element) node; path = path.substring(k + 1); NodeList nodeList = ((Element) node).getChildNodes(); Node n; for (int i = 0; i < nodeList.getLength(); i++) { n = nodeList.item(i); if ((n instanceof Element) && ((n = getElementViaPath(n, path)) != null)) return (Element) n; } } return null; } /** * Get the text content of an element identified by a path, * where the path elements can include an index. The first * path element must not have an index, and its name must * match the name of the starting node. If the starting * node is a Document, the root Element of the document is * used as the starting point. Path elements must be separated * by the slash character. If the path starts with a slash, * the slash is ignored. If the element or attribute identified * by the path is not present as a child of the starting node, * the empty string is returned. If a path element identifies * an attribute, any subsequent path elements are ignored. * A path is in the form: /e1/e2/e3/... or /e1/e2/@attr * Note the slash preceding the attribute's @-sign. * @param node the starting node for the path. The first path * element must match the name of this node. * @param path the path to the target node. * @return the full text value of the target node (including all * descendent text nodes), or the empty string if the target is * not a descendent of the starting node. */ public static String getTextContent(Node node, String path) { if (node instanceof Document) node = ((Document) node).getDocumentElement(); if (!(node instanceof Element)) return ""; Element el = (Element) node; path = path.replaceAll("\\s", ""); if (path.startsWith("/")) path = path.substring(1); String[] pathElements = path.split("/"); if (!pathElements[0].equals(el.getTagName())) return ""; for (int i = 1; i < pathElements.length; i++) { String pe = pathElements[i]; if (pe.startsWith("@")) { //If this path element identifies an attribute, return it //and ignore any further path elements. return el.getAttribute(pe.substring(1)); } else { //This path element identifies an Element. It may have an index. //Get the index, if present, and get the element name. int n = 0; int k = pe.indexOf("["); int kk = pe.lastIndexOf("]"); if ((k != -1) && (k < kk)) { try { n = Integer.parseInt(pe.substring(k + 1, kk)); } catch (Exception ex) { return ""; } pe = pe.substring(0, k); } else if (k != kk) return ""; //We now have the element name and the index. //Find the identified Element. We have to count //matching elements to find the one identified //by the index. int nn = 0; Node child = el.getFirstChild(); while (child != null) { if ((child.getNodeType() == Node.ELEMENT_NODE) && child.getNodeName().equals(pe)) { if (n == nn) break; nn++; } child = child.getNextSibling(); } //If the child is null, we didn't find the identified Element. if (child == null) return ""; //If we get here, we found it, now look for the next one. el = (Element) child; } } //Okay, we must be at the end of the path, and it must be an Element. //Return the text content of the element. return el.getTextContent(); } }