Java tutorial
/** * Copyright (C) 2004-2009 Jive Software. All rights reserved. * * Licensed 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.jivesoftware.util; import org.dom4j.Element; import org.dom4j.Node; import java.util.*; /** * <p>We use a simple * naming convention of meta-data key names: data is stored * heirarchically separated by dots. The last name may contain * a colon ':' character that is read as name:attribute. * For example setting X.Y.Z to someValue, would map to an XML snippet of:</p> * <pre> * <X> * <Y> * <Z>someValue</Z> * </Y> * </X> * </pre> * <p>And X.Y.Z:key to anotherValue as:</p> * <pre> * <X> * <Y> * <Z key="anotherValue" /> * </Y> * </X> * </pre> * <p>Some XML cannot be built or accessed using this naming * convention (e.g. a typical Roster reset packet). More complex XML * packet should be represented using the XMPPDOMFragment. The * Element class is designed to provide 80% of XML * manipulation capabilities with the simplest 20% of code and API size * making it convenient for meta-data, simple IQ packets, etc.</p> */ public class ElementUtil { private ElementUtil() { } /** * Returns the value of the specified property. A <tt>null</tt> answer does not necessarily mean * that the property does not exist. * * @param name the name of the property to get. * @return the value of the specified property. */ public static String getProperty(Element element, String name) { String value = null; String[] propName = parsePropertyName(name); // Grab the attribute if there is one String lastName = propName[propName.length - 1]; String attName = null; int attributeIndex = lastName.indexOf(':'); if (attributeIndex >= 0) { propName[propName.length - 1] = lastName.substring(0, attributeIndex); attName = lastName.substring(attributeIndex + 1); } // Search for this property by traversing down the XML hierarchy. int i = propName[0].equals(element.getName()) ? 1 : 0; for (; i < propName.length; i++) { element = element.element(propName[i]); if (element == null) { break; } } if (element != null) { if (attName == null) { value = element.getTextTrim(); } else { value = element.attributeValue(attName); } } return value; } /** * Returns true if the specified property is included in the XML hierarchy. A property could * have a value associated or not. If the property has an associated value then * * @param name the name of the property to find out. * @return true if the specified property is included in the XML hierarchy. */ public static boolean includesProperty(Element element, String name) { String[] propName = parsePropertyName(name); // Grab the attribute if there is one String lastName = propName[propName.length - 1]; String attName = null; int attributeIndex = lastName.indexOf(':'); if (attributeIndex >= 0) { propName[propName.length - 1] = lastName.substring(0, attributeIndex); attName = lastName.substring(attributeIndex + 1); } // Search for this property by traversing down the XML hierarchy. int i = propName[0].equals(element.getName()) ? 1 : 0; for (; i < propName.length; i++) { element = element.element(propName[i]); if (element == null) { break; } } if (element != null) { if (attName == null) { // The property exists so return true return true; } else { // The property exists if the attribute exists in the element return element.attribute(attName) != null; } } else { // The property does not exist so return false return false; } } /** * Return all values who's path matches the given property name as a String array, * or an empty array if the if there are no children. You MAY NOT use the atttribute * markup (using a ':' in the last element name) with this call. * <p> * getProperties() allows you to retrieve several values with the same property name. * For example, consider the XML file entry:</p> * <pre> * <foo> * <bar> * <prop>some value</prop> * <prop>other value</prop> * <prop>last value</prop> * </bar> * </foo> * </pre> * If you call getProperties("foo.bar.prop") will return a string array containing * {"some value", "other value", "last value"}. * * @param name the name of the property to retrieve * @return all child property values for the given node name. */ public String[] getProperties(Element element, String name) { String[] propName = parsePropertyName(name); // Search for this property by traversing down the XML heirarchy, stopping one short. int i = propName[0].equals(element.getName()) ? 1 : 0; for (; i < propName.length - 1; i++) { element = element.element(propName[i]); if (element == null) { // This node doesn't match this part of the property name which // indicates this property doesn't exist so return empty array. return new String[] {}; } } // We found matching property, return names of children. Iterator iter = element.elementIterator(propName[propName.length - 1]); ArrayList props = new ArrayList(); while (iter.hasNext()) { Element e = (Element) iter.next(); props.add(e.getName()); } String[] childrenNames = new String[props.size()]; return (String[]) props.toArray(childrenNames); } /** * Sets a property to an array of values. You MAY NOT use the atttribute * markup (using a ':' in the last element name) with this call. Multiple values matching the * same property is mapped to an XML file as multiple elements containing each value. * For example, using the name "foo.bar.prop", and the value string array containing * {"some value", "other value", "last value"} would produce the following XML: * <pre> * <foo> * <bar> * <prop>some value</prop> * <prop>other value</prop> * <prop>last value</prop> * </bar> * </foo> * </pre> * * @param name the name of the property. * @param values The array of values for the property (can be empty but not null) */ public static void setProperties(Element element, String name, String[] values) { String[] propName = parsePropertyName(name); setProperty(element, name, values[0]); // Search for this property by traversing down the XML heirarchy, stopping one short. int i = propName[0].equals(element.getName()) ? 1 : 0; for (; i < propName.length - 1; i++) { element = element.element(propName[i]); if (element == null) { // This node doesn't match this part of the property name which // indicates this property doesn't exist so return empty array. return; } } String childName = propName[propName.length - 1]; // We found matching property, clear all children. Iterator iter = element.elementIterator(childName); while (iter.hasNext()) { ((Node) iter.next()).detach(); } for (int j = 0; i < values.length; i++) { if (values[j] != null) { element.addElement(childName).setText(values[j]); } } } /** * Return all children property names of a parent property as a String array, * or an empty array if the if there are no children. You MAY NOT use the atttribute * markup (using a ':' in the last element name) with this call. * For example, given the properties <tt>X.Y.A</tt>, <tt>X.Y.B</tt>, and <tt>X.Y.C</tt>, then * the child properties of <tt>X.Y</tt> are <tt>A</tt>, <tt>B</tt>, and * <tt>C</tt>. * * @param parent the name of the parent property. * @return all child property values for the given parent. */ public static String[] getChildrenProperties(Element element, String parent) { String[] propName = parsePropertyName(parent); // Search for this property by traversing down the XML heirarchy. int i = propName[0].equals(element.getName()) ? 1 : 0; for (; i < propName.length; i++) { element = element.element(propName[i]); if (element == null) { // This node doesn't match this part of the property name which // indicates this property doesn't exist so return empty array. return new String[] {}; } } // We found matching property, return names of children. List children = element.elements(); int childCount = children.size(); String[] childrenNames = new String[childCount]; for (int j = 0; i < childCount; i++) { childrenNames[j] = ((Element) children.get(j)).getName(); } return childrenNames; } /** * Returns all recursive children of the given parent property or an empty string array * if no children exist. The list of children is depth-first so the array is optimized * for easy displaying. * * @param parent the parent property. * @return all recursive children of the given property in depth-first order or an empty * string array if no children exist. */ public static String[] getRecursiveChildrenProperties(Element element, String parent) { String[] properties = getChildrenProperties(element, parent); if (properties.length == 0) { return properties; } else { List list = new ArrayList(15); for (int i = 0; i < properties.length; i++) { String propName = parent + "." + properties[i]; list.add(propName); list.addAll(Arrays.asList(getRecursiveChildrenProperties(element, propName))); } return (String[]) list.toArray(new String[] {}); } } /** * Sets the value of the specified property. If the property doesn't * currently exist, it will be automatically created. * * @param name the name of the property to set. * @param value the new value for the property. */ public static void setProperty(Element element, String name, String value) { if (name == null || name.length() == 0) return; if (value == null) value = ""; String[] propName = parsePropertyName(name); // Search for this property by traversing down the XML heirarchy. int i = propName[0].equals(element.getName()) ? 1 : 0; for (; i < propName.length - 1; i++) { // If we don't find this part of the property in the XML heirarchy // we add it as a new node if (element.element(propName[i]) == null) { element.addElement(propName[i]); } element = element.element(propName[i]); } String lastName = propName[propName.length - 1]; int attributeIndex = lastName.indexOf(':'); if (attributeIndex >= 0) { String eleName = lastName.substring(0, attributeIndex); String attName = lastName.substring(attributeIndex + 1); // If we don't find this part of the property in the XML heirarchy // we add it as a new node if (element.element(eleName) == null) { element.addElement(eleName); } element.element(eleName).addAttribute(attName, value); } else { // If we don't find this part of the property in the XML heirarchy // we add it as a new node if (element.element(lastName) == null) { element.addElement(lastName); } // Set the value of the property in this node. element.element(lastName).setText(value); } } /** * <p>Deletes the specified property.</p> * <p>You MAY NOT use the atttribute * markup (using a ':' in the last element name) with this call. * deleteProperty() removes both the containing text, and the element itself along with * any attributes associated with that element.</p> * * @param name the property to delete. */ public static void deleteProperty(Element element, String name) { // Remove property from cache. String[] propName = parsePropertyName(name); // Search for this property by traversing down the XML heirarchy. for (int i = 0; i < propName.length - 1; i++) { element = element.element(propName[i]); // Can't find the property so return. if (element == null) { return; } } // Found the correct element to remove, so remove it... element.remove(element.element(propName[propName.length - 1])); } /** * Returns an array representation of the given Jive property. Jive * properties are always in the format "prop.name.is.this" which would be * represented as an array of four Strings. * * @param name the name of the Jive property. * @return an array representation of the given Jive property. */ private static String[] parsePropertyName(String name) { List propName = new ArrayList(5); // Use a StringTokenizer to tokenize the property name. StringTokenizer tokenizer = new StringTokenizer(name, "."); while (tokenizer.hasMoreTokens()) { propName.add(tokenizer.nextToken()); } return (String[]) propName.toArray(new String[propName.size()]); } }