Name: gsC80088 Date: 03/14/99


Telling a JEditorPane to display a particular HTML document
frequently results in errors. It is understandable that
there is HTML it doesn't understand, but not so understandable
that it crashes. For example, doing setPage on
http://java.sun.com/ results in:
Exception occurred during event dispatching:
javax.swing.text.StateInvariantError: infinite loop in formatting
at javax.swing.text.ParagraphView.rebuildRows(Compiled Code)
at javax.swing.text.ParagraphView.layout(Compiled Code)
(etc).

Doing setPage on http://www.apl.jhu.edu/~hall/java/ results in:
java.lang.ArrayIndexOutOfBoundsException
at javax.swing.text.CompositeView.getView(Compiled Code)
at javax.swing.text.TableView.addProxy(Compiled Code)
at javax.swing.text.TableView.loadProxyCells(Compiled Code)
(etc).

Many other URLs work fine.

I guess my point is two fold: (A) provide some general guidance
on what isn't supported (e.g. max file length, HTML 3.2
constructs not supported, etc.), and
(B) don't crash -- ignore unknown HTML elements and attributes
instead. JEditorPane is too brittle now.

Following is a very simplistic test case that displays
a JEditorPane and lets you enter a URL to display. It
illustrates the problem on the two URLs mentioned above,
and you can try others as well. (Not sure you need this test
case, but I'm including it just in case).

Browser.java:
==============

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

public class Browser extends JFrame implements HyperlinkListener, ActionListener {
  public static void main(String[] args) {
    new Browser();
  }

  private JPanel topPanel;
  private JLabel urlLabel;
  private JTextField urlField;
  private JButton submitButton;
  private JEditorPane htmlPane;

  public Browser() {
    super("Simple Java2 Browser");
    addWindowListener(new ExitListener());
    WindowUtilities.setNativeLookAndFeel();
    getContentPane().setBackground(Color.white);

    topPanel = new JPanel();
    topPanel.setBackground(Color.white);
    urlLabel = new JLabel("URL:");
    urlField = new JTextField(30);
    urlField.addActionListener(this);
    submitButton = new JButton("Go to URL");
    submitButton.addActionListener(this);
    topPanel.add(urlLabel);
    topPanel.add(urlField);
    topPanel.add(submitButton);
    getContentPane().add(topPanel, BorderLayout.NORTH);

    try {
htmlPane =
new JEditorPane("http://www.apl.jhu.edu/~hall/");
htmlPane.setEditable(false);
htmlPane.addHyperlinkListener(this);
JScrollPane scrollPane = new JScrollPane(htmlPane);
getContentPane().add(scrollPane, BorderLayout.CENTER);
    } catch(IOException ioe) {
       System.out.println("IOException building HTML pane: " + ioe);
    }

    setSize(600, 400);
    setVisible(true);
  }

  public void actionPerformed(ActionEvent event) {
    try {
      htmlPane.setPage(new URL(urlField.getText()));
    } catch(IOException ioe) {
       System.out.println("IOException following linkL " + ioe);
    }
  }

  public void hyperlinkUpdate(HyperlinkEvent event) {
    System.out.println("Hyperline event of type " + event.getEventType());
    try {
      htmlPane.setPage(event.getURL());
    } catch(IOException ioe) {
       System.out.println("IOException following linkL " + ioe);
    }
  }
}
(Review ID: 52263)
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