//XMLTree.java
//Uses the following files

Uses the following files:

    * XMLFrame.java:Swing application to select an XML document and display in a JTree.

ExtensionFileFilter.java Allows you to specify which file extensions will be displayed in a JFileChooser.

test.xml Default file loaded if none selected by user. 

perennials.xml and perennials.dtd Data on daylilies and corresponding DTD.

WindowUtilities.java  

ExitListener.java. 

//XMLTree.java as follows
import java.awt.*;
import javax.swing.*;
import javax.swing.tree.*;
import java.io.*;
import org.w3c.dom.*;
import javax.xml.parsers.*;

/** Given a filename or a name and an input stream,
 *  this class generates a JTree representing the
 *  XML structure contained in the file or stream.
 *  Parses with DOM then copies the tree structure
 *  (minus text and comment nodes).
 *
 *  Taken from Core Web Programming from 
 *  Prentice Hall and Sun Microsystems Press,
 *  
 *  © 2001 Marty Hall and Larry Brown;
 *  may be freely used or adapted. 
 */

public class XMLTree extends JTree {
  public XMLTree(String filename) throws IOException {
    this(filename, new FileInputStream(new File(filename)));
  }

  public XMLTree(String filename, InputStream in) {
    super(makeRootNode(in));
  }

  // This method needs to be static so that it can be called
  // from the call to the parent constructor (super), which
  // occurs before the object is really built.
  
  private static DefaultMutableTreeNode
                                 makeRootNode(InputStream in) {
    try {
      // Use JAXP's DocumentBuilderFactory so that there
      // is no code here that is dependent on a particular
      // DOM parser. Use the system property
      // javax.xml.parsers.DocumentBuilderFactory (set either
      // from Java code or by using the -D option to "java").
      // or jre_dir/lib/jaxp.properties to specify this.
      DocumentBuilderFactory builderFactory =
        DocumentBuilderFactory.newInstance();
      DocumentBuilder builder =
        builderFactory.newDocumentBuilder();
      // Standard DOM code from hereon. The "parse"
      // method invokes the parser and returns a fully parsed
      // Document object. We'll then recursively descend the
      // tree and copy non-text nodes into JTree nodes.
      Document document = builder.parse(in);
      document.getDocumentElement().normalize();
      Element rootElement = document.getDocumentElement();
      DefaultMutableTreeNode rootTreeNode =
        buildTree(rootElement);
      return(rootTreeNode);
    } catch(Exception e) {
      String errorMessage =
        "Error making root node: " + e;
      System.err.println(errorMessage);
      e.printStackTrace();
      return(new DefaultMutableTreeNode(errorMessage));
    }
  }

  private static DefaultMutableTreeNode
                              buildTree(Element rootElement) {
    // Make a JTree node for the root, then make JTree
    // nodes for each child and add them to the root node.
    // The addChildren method is recursive.
    DefaultMutableTreeNode rootTreeNode =
      new DefaultMutableTreeNode(treeNodeLabel(rootElement));
    addChildren(rootTreeNode, rootElement);
    return(rootTreeNode);
  }

  private static void addChildren
                       (DefaultMutableTreeNode parentTreeNode,
                        Node parentXMLElement) {
    // Recursive method that finds all the child elements
    // and adds them to the parent node. We have two types
    // of nodes here: the ones corresponding to the actual
    // XML structure and the entries of the graphical JTree.
    // The convention is that nodes corresponding to the
    // graphical JTree will have the word "tree" in the
    // variable name. Thus, "childElement" is the child XML
    // element whereas "childTreeNode" is the JTree element.
    // This method just copies the non-text and non-comment
    // nodes from the XML structure to the JTree structure.
    
    NodeList childElements =
      parentXMLElement.getChildNodes();
    for(int i=0; i
  // JTree Node:  blah
  // XML Element: 
  // JTree Node:  blah (foo=bar, baz=quux)

  private static String treeNodeLabel(Node childElement) {
    NamedNodeMap elementAttributes =
      childElement.getAttributes();
    String treeNodeLabel = childElement.getNodeName();
    if (elementAttributes != null &&
        elementAttributes.getLength() > 0) {
      treeNodeLabel = treeNodeLabel + " (";
      int numAttributes = elementAttributes.getLength();
      for(int i=0; i 0) {
          treeNodeLabel = treeNodeLabel + ", ";
        }
        treeNodeLabel =
          treeNodeLabel + attribute.getNodeName() +
          "=" + attribute.getNodeValue();
      }
      treeNodeLabel = treeNodeLabel + ")";
    }
    return(treeNodeLabel);
  }
}

XMLFrame.java Swing application to select an XML document and display in a JTree.

import java.awt.*;
import javax.swing.*;
import java.io.*;

/** Invokes an XML parser on an XML document and displays
 *  the document in a JTree. Both the parser and the
 *  document can be specified by the user. The parser
 *  is specified by invoking the program with
 *  java -Djavax.xml.parsers.DocumentBuilderFactory=xxx XMLFrame
 *  If no parser is specified, the Apache Xerces parser is used.
 *  The XML document can be supplied on the command
 *  line, but if it is not given, a JFileChooser is used
 *  to interactively select the file of interest.
 *
 *  Taken from Core Web Programming from 
 *  Prentice Hall and Sun Microsystems Press,
 
 *  © 2001 Marty Hall and Larry Brown;
 *  may be freely used or adapted. 
 */

public class XMLFrame extends JFrame {
  public static void main(String[] args) {
    String jaxpPropertyName =
      "javax.xml.parsers.DocumentBuilderFactory";
    // Pass the parser factory in on the command line with
    // -D to override the use of the Apache parser.
    if (System.getProperty(jaxpPropertyName) == null) {
      String apacheXercesPropertyValue =
        "org.apache.xerces.jaxp.DocumentBuilderFactoryImpl";
      System.setProperty(jaxpPropertyName,
                         apacheXercesPropertyValue);
    }
    String filename;
    if (args.length > 0) {
      filename = args[0];
    } else {
      String[] extensions = { "xml", "tld" };
      WindowUtilities.setNativeLookAndFeel();
      filename = ExtensionFileFilter.getFileName(".",
                                                 "XML Files",
                                                 extensions);
      if (filename == null) {
        filename = "test.xml";
      }
    }
    new XMLFrame(filename);
  }

  public XMLFrame(String filename) {
    try {
      WindowUtilities.setNativeLookAndFeel();
      JTree tree = new XMLTree(filename);
      JFrame frame = new JFrame(filename);
      frame.addWindowListener(new ExitListener());
      Container content = frame.getContentPane();
      content.add(new JScrollPane(tree));
      frame.pack();
      frame.setVisible(true);
    } catch(IOException ioe) {
      System.out.println("Error creating tree: " + ioe);
    }
  }
}

ExtensionFileFilter.java Allows you to specify which file extensions will be displayed in a JFileChooser.

import java.io.File;
import java.util.*;
import javax.swing.*;
import javax.swing.filechooser.FileFilter;

/** A FileFilter that lets you specify which file extensions 
 *  will be displayed. Also includes a static getFileName 
 *  method that users can call to pop up a JFileChooser for 
 *  a set of file extensions.
 *  


 *  Adapted from Sun SwingSet demo.
 *
 *  Taken from Core Web Programming from 
 *  Prentice Hall and Sun Microsystems Press,
 *  © 2001 Marty Hall and Larry Brown;
 *  may be freely used or adapted. 
 */

public class ExtensionFileFilter extends FileFilter {
  public static final int LOAD = 0;
  public static final int SAVE = 1;
  private String description;
  private boolean allowDirectories;
  private Hashtable extensionsTable = new Hashtable();
  private boolean allowAll = false;

  public ExtensionFileFilter(boolean allowDirectories) {
    this.allowDirectories = allowDirectories;
  }

  public ExtensionFileFilter() {
    this(true);
  }
  
  
  public static String getFileName(String initialDirectory,
                                   String description,
                                   String extension) {
    String[] extensions = new String[]{ extension };
    return(getFileName(initialDirectory, description, 
                       extensions, LOAD));
  }  

  public static String getFileName(String initialDirectory,
                                   String description,
                                   String extension,
                                   int mode) {
    String[] extensions = new String[]{ extension };
    return(getFileName(initialDirectory, description, 
                       extensions, mode));
  }

  public static String getFileName(String initialDirectory,
                                   String description,
                                   String[] extensions) {
    return(getFileName(initialDirectory, description, 
                       extensions, LOAD));
  }


  /** Pops up a JFileChooser that lists files with the 
   *  specified extensions. If the mode is SAVE, then the 
   *  dialog will have a Save button; otherwise, the dialog 
   *  will have an Open button. Returns a String corresponding
   *  to the file's pathname, or null if Cancel was selected.
   */

  public static String getFileName(String initialDirectory,
                                   String description,
                                   String[] extensions,
                                   int mode) {
    ExtensionFileFilter filter = new ExtensionFileFilter();
    filter.setDescription(description);
    for(int i=0; i


WindowUtilities.java

import javax.swing.*;
import java.awt.*;   // For Color and Container classes.

/** A few utilities that simplify using windows in Swing. 
 *
 *  Taken from Core Web Programming from 
 *  Prentice Hall and Sun Microsystems Press,
 * 
 *  © 2001 Marty Hall and Larry Brown;
 *  may be freely used or adapted.
 */

public class WindowUtilities {

  /** Tell system to use native look and feel, as in previous
   *  releases. Metal (Java) LAF is the default otherwise.
   */

  public static void setNativeLookAndFeel() {
    try {
     UIManager.setLookAndFeel(
       UIManager.getSystemLookAndFeelClassName());
    } catch(Exception e) {
      System.out.println("Error setting native LAF: " + e);
    }
  }

  public static void setJavaLookAndFeel() {
    try {
     UIManager.setLookAndFeel(
       UIManager.getCrossPlatformLookAndFeelClassName());
    } catch(Exception e) {
      System.out.println("Error setting Java LAF: " + e);
    }
  }

   public static void setMotifLookAndFeel() {
    try {
      UIManager.setLookAndFeel(
        "com.sun.java.swing.plaf.motif.MotifLookAndFeel");
    } catch(Exception e) {
      System.out.println("Error setting Motif LAF: " + e);
    }
  }

  /** A simplified way to see a JPanel or other Container. Pops
   *  up a JFrame with specified Container as the content pane.
   */

  public static JFrame openInJFrame(Container content,
                                    int width,
                                    int height,
                                    String title,
                                    Color bgColor) {
    JFrame frame = new JFrame(title);
    frame.setBackground(bgColor);
    content.setBackground(bgColor);
    frame.setSize(width, height);
    frame.setContentPane(content);
    frame.addWindowListener(new ExitListener());
    frame.setVisible(true);
    return(frame);
  }

  /** Uses Color.white as the background color. */

  public static JFrame openInJFrame(Container content,
                                    int width,
                                    int height,
                                    String title) {
    return(openInJFrame(content, width, height,
                        title, Color.white));
  }

  /** Uses Color.white as the background color, and the
   *  name of the Container's class as the JFrame title.
   */

  public static JFrame openInJFrame(Container content,
                                    int width,
                                    int height) {
    return(openInJFrame(content, width, height,
                        content.getClass().getName(),
                        Color.white));
  }
}



EXITListener.java

import java.awt.*;
import java.awt.event.*;

/** A listener that you attach to the top-level JFrame of
 *  your application, so that quitting the frame exits the 
 *  application.
 *
 *  Taken from Core Web Programming from 
 *  Prentice Hall and Sun Microsystems Press,
 *  
 *  © 2001 Marty Hall and Larry Brown;
 *  may be freely used or adapted. 
 */
public class ExitListener extends WindowAdapter {
  public void windowClosing(WindowEvent event) {
    System.exit(0);
  }
}