Simplified implementation of a Node from a Document Object Model (DOM) : Node « XML « 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.
 */


import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;


/**
 * Simplified implementation of a Node from a Document Object Model (DOM)
 * parse of an XML document.  This class is used to represent a DOM tree
 * so that the XML parser's implementation of <code>org.w3c.dom</code> need
 * not be visible to the remainder of Jasper.
 * <p>
 * <strong>WARNING</strong> - Construction of a new tree, or modifications
 * to an existing one, are not thread-safe and such accesses must be
 * synchronized.
 *
 * @author Craig R. McClanahan
 * @version $Revision: 515 $ $Date: 2008-03-17 22:02:23 +0100 (Mon, 17 Mar 2008) $
 */

public class TreeNode {


    // ----------------------------------------------------------- Constructors


    /**
     * Construct a new node with no parent.
     *
     * @param name The name of this node
     */
    public TreeNode(String name) {

        this(name, null);

    }


    /**
     * Construct a new node with the specified parent.
     *
     * @param name The name of this node
     * @param parent The node that is the parent of this node
     */
    public TreeNode(String name, TreeNode parent) {

        super();
        this.name = name;
        this.parent = parent;
        if (this.parent != null)
            this.parent.addChild(this);

    }


    // ----------------------------------------------------- Instance Variables


    /**
     * The attributes of this node, keyed by attribute name,
     * Instantiated only if required.
     */
    protected HashMap attributes = null;


    /**
     * The body text associated with this node (if any).
     */
    protected String body = null;


    /**
     * The children of this node, instantiated only if required.
     */
    protected ArrayList children = null;


    /**
     * The name of this node.
     */
    protected String name = null;


    /**
     * The parent node of this node.
     */
    protected TreeNode parent = null;


    // --------------------------------------------------------- Public Methods


    /**
     * Add an attribute to this node, replacing any existing attribute
     * with the same name.
     *
     * @param name The attribute name to add
     * @param value The new attribute value
     */
    public void addAttribute(String name, String value) {

        if (attributes == null)
            attributes = new HashMap();
        attributes.put(name, value);

    }


    /**
     * Add a new child node to this node.
     *
     * @param node The new child node
     */
    public void addChild(TreeNode node) {

        if (children == null)
            children = new ArrayList();
        children.add(node);

    }


    /**
     * Return the value of the specified node attribute if it exists, or
     * <code>null</code> otherwise.
     *
     * @param name Name of the requested attribute
     */
    public String findAttribute(String name) {

        if (attributes == null)
            return (null);
        else
            return ((String) attributes.get(name));

    }


    /**
     * Return an Iterator of the attribute names of this node.  If there are
     * no attributes, an empty Iterator is returned.
     */
    public Iterator findAttributes() {

        if (attributes == null)
            return (Collections.EMPTY_LIST.iterator());
        else
            return (attributes.keySet().iterator());

    }


    /**
     * Return the first child node of this node with the specified name,
     * if there is one; otherwise, return <code>null</code>.
     *
     * @param name Name of the desired child element
     */
    public TreeNode findChild(String name) {

        if (children == null)
            return (null);
        Iterator items = children.iterator();
        while (items.hasNext()) {
            TreeNode item = (TreeNode) items.next();
            if (name.equals(item.getName()))
                return (item);
        }
        return (null);

    }


    /**
     * Return an Iterator of all children of this node.  If there are no
     * children, an empty Iterator is returned.
     */
    public Iterator findChildren() {

        if (children == null)
            return (Collections.EMPTY_LIST.iterator());
        else
            return (children.iterator());

    }


    /**
     * Return an Iterator over all children of this node that have the
     * specified name.  If there are no such children, an empty Iterator
     * is returned.
     *
     * @param name Name used to select children
     */
    public Iterator findChildren(String name) {

        if (children == null)
            return (Collections.EMPTY_LIST.iterator());

        ArrayList results = new ArrayList();
        Iterator items = children.iterator();
        while (items.hasNext()) {
            TreeNode item = (TreeNode) items.next();
            if (name.equals(item.getName()))
                results.add(item);
        }
        return (results.iterator());

    }


    /**
     * Return the body text associated with this node (if any).
     */
    public String getBody() {

        return (this.body);

    }


    /**
     * Return the name of this node.
     */
    public String getName() {

        return (this.name);

    }


    /**
     * Remove any existing value for the specified attribute name.
     *
     * @param name The attribute name to remove
     */
    public void removeAttribute(String name) {

        if (attributes != null)
            attributes.remove(name);

    }


    /**
     * Remove a child node from this node, if it is one.
     *
     * @param node The child node to remove
     */
    public void removeNode(TreeNode node) {

        if (children != null)
            children.remove(node);

    }


    /**
     * Set the body text associated with this node (if any).
     *
     * @param body The body text (if any)
     */
    public void setBody(String body) {

        this.body = body;

    }


    /**
     * Return a String representation of this TreeNode.
     */
    public String toString() {

        StringBuffer sb = new StringBuffer();
        toString(sb, 0, this);
        return (sb.toString());

    }


    // ------------------------------------------------------ Protected Methods


    /**
     * Append to the specified StringBuffer a character representation of
     * this node, with the specified amount of indentation.
     *
     * @param sb The StringBuffer to append to
     * @param indent Number of characters of indentation
     * @param node The TreeNode to be printed
     */
    protected void toString(StringBuffer sb, int indent,
                            TreeNode node) {

        int indent2 = indent + 2;

        // Reconstruct an opening node
        for (int i = 0; i < indent; i++)
            sb.append(' ');
        sb.append('<');
        sb.append(node.getName());
        Iterator names = node.findAttributes();
        while (names.hasNext()) {
            sb.append(' ');
            String name = (String) names.next();
            sb.append(name);
            sb.append("=\"");
            String value = node.findAttribute(name);
            sb.append(value);
            sb.append("\"");
        }
        sb.append(">\n");

        // Reconstruct the body text of this node (if any)
        String body = node.getBody();
        if ((body != null) && (body.length() > 0)) {
            for (int i = 0; i < indent2; i++)
                sb.append(' ');
            sb.append(body);
            sb.append("\n");
        }

        // Reconstruct child nodes with extra indentation
        Iterator children = node.findChildren();
        while (children.hasNext()) {
            TreeNode child = (TreeNode) children.next();
            toString(sb, indent2, child);
        }

        // Reconstruct a closing node marker
        for (int i = 0; i < indent; i++)
            sb.append(' ');
        sb.append("</");
        sb.append(node.getName());
        sb.append(">\n");

    }


}








33.29.Node
33.29.1.Add a text node to the element
33.29.2.Add a text node to the beginning of the element
33.29.3.Add a text node before the last child of the element
33.29.4.Add a text node in front of the new item element
33.29.5.Adding a Text Node to a DOM Document
33.29.6.Removing a Node from a DOM Document
33.29.7.Remove All nodes
33.29.8.Get the text node
33.29.9.Change a particular node in XML
33.29.10.Add another element after the first child of the root element
33.29.11.Create a new element and move the middle text node to it
33.29.12.Move all children of the element in front of the element
33.29.13.Split the node at the beginning of the word
33.29.14.Compare two DOM Nodes from JBoss
33.29.15.Convert NodeList To Node Array
33.29.16.Convert node element To String
33.29.17.Search our next siblings for a given node
33.29.18.Search earlier siblings for a given node
33.29.19.Returns a first child DOM Node of type ELEMENT_NODE for the specified Node
33.29.20.Search up the tree for a given node
33.29.21.Get the first text node associated with this element
33.29.22.Simplified implementation of a Node from a Document Object Model (DOM)
33.29.23.Returns a list of value for the given node
33.29.24.Returns the value of the child node with the given name
33.29.25.Remove this node from its parent.
33.29.26.Find the first text descendent node of an element
33.29.27.Copies the source tree into the specified place in a destination tree.
33.29.28.DOM helper for root element
33.29.29.Compare two DOM Nodes