/* * Copyright (c) 2000 David Flanagan.  All rights reserved. * This code is from the book Java Examples in a Nutshell, 2nd Edition. * It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied. * You may study, use, and modify it for any non-commercial purpose. * You may distribute it non-commercially as long as you retain this notice. * For a commercial use license, or to purchase the book (recommended), * visit http://www.davidflanagan.com/javaexamples2. */package com.davidflanagan.examples.xml;import org.w3c.dom.*;                // Core DOM classesimport org.w3c.dom.traversal.*;      // TreeWalker and related DOM classesimport org.apache.xerces.parsers.*;  // Apache Xerces parser classesimport org.xml.sax.*;                // Xerces DOM parser uses some SAX classesimport javax.swing.*;                // Swing classes import javax.swing.tree.*;           // TreeModel and related classesimport javax.swing.event.*;          // Tree-related event classesimport java.io.*;                    // For reading the input XML file/** * This class implements the Swing TreeModel interface so that the DOM tree * returned by a TreeWalker can be displayed in a JTree component. **/public class DOMTreeWalkerTreeModel implements TreeModel {    TreeWalker walker;  // The TreeWalker we're modeling for JTree        /** Create a TreeModel for the specified TreeWalker */    public DOMTreeWalkerTreeModel(TreeWalker walker) { this.walker = walker; }    /**      * Create a TreeModel for a TreeWalker that returns all nodes     * in the specified document     **/    public DOMTreeWalkerTreeModel(Document document) {	DocumentTraversal dt = (DocumentTraversal)document;	walker = dt.createTreeWalker(document, NodeFilter.SHOW_ALL,null,false);    }    /**      * Create a TreeModel for a TreeWalker that returns the specified      * element and all of its descendant nodes.     **/    public DOMTreeWalkerTreeModel(Element element) {	DocumentTraversal dt = (DocumentTraversal)element.getOwnerDocument();	walker = dt.createTreeWalker(element, NodeFilter.SHOW_ALL, null,false);    }    // Return the root of the tree     public Object getRoot() { return walker.getRoot(); }        // Is this node a leaf? (Leaf nodes are displayed differently by JTree)    public boolean isLeaf(Object node) {	walker.setCurrentNode((Node)node);   // Set current node	Node child = walker.firstChild();    // Ask for a child	return (child == null);              // Does it have any?    }        // How many children does this node have?    public int getChildCount(Object node) {	walker.setCurrentNode((Node)node);   // Set the current node	// TreeWalker doesn't count children for us, so we count ourselves	int numkids = 0;	Node child = walker.firstChild();    // Start with the first child	while(child != null) {               // Loop 'till there are no more	    numkids++;                       // Update the count	    child = walker.nextSibling();    // Get next child	}	return numkids;                      // This is the number of children    }        // Return the specified child of a parent node.    public Object getChild(Object parent, int index) {	walker.setCurrentNode((Node)parent);  // Set the current node	// TreeWalker provides sequential access to children, not random	// access, so we've got to loop through the kids one by one	Node child = walker.firstChild();	while(index-- > 0) child = walker.nextSibling();	return child;    }        // Return the index of the child node in the parent node    public int getIndexOfChild(Object parent, Object child) {	walker.setCurrentNode((Node)parent);    // Set current node	int index = 0;	Node c = walker.firstChild();           // Start with first child	while((c != child) && (c != null)) {    // Loop 'till we find a match	    index++;	    c = walker.nextSibling();           // Get the next child	}	return index;                           // Return matching position    }        // Only required for editable trees; unimplemented here.    public void valueForPathChanged(TreePath path, Object newvalue) {}        // This TreeModel never fires any events (since it is not editable)    // so event listener registration methods are left unimplemented    public void addTreeModelListener(TreeModelListener l) {}    public void removeTreeModelListener(TreeModelListener l) {}    /**     * This main() method demonstrates the use of this class, the use of the     * Xerces DOM parser, and the creation of a DOM Level 2 TreeWalker object.     **/    public static void main(String[] args) throws IOException, SAXException {	// Obtain an instance of a Xerces parser to build a DOM tree.	// Note that we are not using the JAXP API here, so this	// code uses Apache Xerces APIs that are not standards	DOMParser parser = new org.apache.xerces.parsers.DOMParser();	// Get a java.io.Reader for the input XML file and 	// wrap the input file in a SAX input source	Reader in = new BufferedReader(new FileReader(args[0]));	InputSource input = new org.xml.sax.InputSource(in);	// Tell the Xerces parser to parse the input source	parser.parse(input);	// Ask the parser to give us our DOM Document.  Once we've got the DOM	// tree, we don't have to use the Apache Xerces APIs any more; from	// here on, we use the standard DOM APIs	Document document = parser.getDocument();	// If we're using a DOM Level 2 implementation, then our Document	// object ought to implement DocumentTraversal 	DocumentTraversal traversal = (DocumentTraversal)document;	// For this demonstration, we create a NodeFilter that filters out	// Text nodes containing only space; these just clutter up the tree	NodeFilter filter = new NodeFilter() {		public short acceptNode(Node n) {		    if (n.getNodeType() == Node.TEXT_NODE) { 			// Use trim() to strip off leading and trailing space.			// If nothing is left, then reject the node			if (((Text)n).getData().trim().length() == 0)			    return NodeFilter.FILTER_REJECT;		    }		    return NodeFilter.FILTER_ACCEPT;		}	    };	// This set of flags says to "show" all node types except comments	int whatToShow = NodeFilter.SHOW_ALL & ~NodeFilter.SHOW_COMMENT;	// Create a TreeWalker using the filter and the flags	TreeWalker walker = traversal.createTreeWalker(document, whatToShow,						       filter, false);	// Instantiate a TreeModel and a JTree to display it	JTree tree = new JTree(new DOMTreeWalkerTreeModel(walker));		// Create a frame and a scrollpane to display the tree, and pop them up	JFrame frame = new JFrame("DOMTreeWalkerTreeModel Demo");	frame.getContentPane().add(new JScrollPane(tree));	frame.setSize(500, 250);	frame.setVisible(true);    }}