elementutil.java

基于Jabber协议的即时消息服务器

package org.jivesoftware.util;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import java.util.StringTokenizer;
import org.dom4j.Element;
import org.dom4j.Node;

/**
 * <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>
 * &lt;X&gt;
 *     &lt;Y&gt;
 *         &lt;Z&gt;someValue&lt;/Z&gt;
 *     &lt;/Y&gt;
 * &lt;/X&gt;
 * </pre>
 * And X.Y.Z:key to anotherValue as:</p>
 * <pre>
 * &lt;X&gt;
 *     &lt;Y&gt;
 *         &lt;Z key="anotherValue" /&gt;
 *     &lt;/Y&gt;
 * &lt;/X&gt;
 * </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 value = null;

        if (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){
                    // 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 true;
    }

    /**
     * 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:
     * <pre>
     * &lt;foo&gt;
     *     &lt;bar&gt;
     *         &lt;prop&gt;some value&lt;/prop&gt;
     *         &lt;prop&gt;other value&lt;/prop&gt;
     *         &lt;prop&gt;last value&lt;/prop&gt;
     *     &lt;/bar&gt;
     * &lt;/foo&gt;
     * </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>
     * &lt;foo&gt;
     *     &lt;bar&gt;
     *         &lt;prop&gt;some value&lt;/prop&gt;
     *         &lt;prop&gt;other value&lt;/prop&gt;
     *         &lt;prop&gt;last value&lt;/prop&gt;
     *     &lt;/bar&gt;
     * &lt;/foo&gt;
     * </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()]);
    }


}