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,
 *  http://www.corewebprogramming.com/.
 *  © 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);
    }
  }
}