JEditorPane and the Swing HTML Package 9
/*
Core SWING Advanced Programming
By Kim Topley
ISBN: 0 13 083292 8
Publisher: Prentice Hall
*/
import java.awt.Color;
import java.awt.Cursor;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.URL;
import java.net.URLConnection;
import java.util.StringTokenizer;
import javax.swing.JCheckBox;
import javax.swing.JEditorPane;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextField;
import javax.swing.UIManager;
import javax.swing.text.BadLocationException;
import javax.swing.text.ChangedCharSetException;
import javax.swing.text.Document;
import javax.swing.text.html.HTMLDocument;
import javax.swing.text.html.HTMLEditorKit;
public class EditorPaneExample9 extends JFrame {
public EditorPaneExample9() {
super("JEditorPane Example 9");
pane = new JEditorPane();
pane.setEditable(false); // Read-only
getContentPane().add(new JScrollPane(pane), "Center");
// Build the panel of controls
JPanel panel = new JPanel();
panel.setLayout(new GridBagLayout());
GridBagConstraints c = new GridBagConstraints();
c.gridwidth = 1;
c.gridheight = 1;
c.anchor = GridBagConstraints.EAST;
c.fill = GridBagConstraints.NONE;
c.weightx = 0.0;
c.weighty = 0.0;
JLabel urlLabel = new JLabel("URL: ", JLabel.RIGHT);
panel.add(urlLabel, c);
JLabel loadingLabel = new JLabel("State: ", JLabel.RIGHT);
c.gridy = 1;
panel.add(loadingLabel, c);
JLabel typeLabel = new JLabel("Type: ", JLabel.RIGHT);
c.gridy = 2;
panel.add(typeLabel, c);
c.gridy = 3;
panel.add(new JLabel(LOAD_TIME), c);
c.gridy = 4;
c.gridwidth = 2;
c.weightx = 1.0;
c.anchor = GridBagConstraints.WEST;
onlineLoad = new JCheckBox("Online Load");
panel.add(onlineLoad, c);
onlineLoad.setSelected(true);
onlineLoad.setForeground(typeLabel.getForeground());
c.gridx = 1;
c.gridy = 0;
c.anchor = GridBagConstraints.EAST;
c.fill = GridBagConstraints.HORIZONTAL;
textField = new JTextField(32);
panel.add(textField, c);
loadingState = new JLabel(spaces, JLabel.LEFT);
loadingState.setForeground(Color.black);
c.gridy = 1;
panel.add(loadingState, c);
loadedType = new JLabel(spaces, JLabel.LEFT);
loadedType.setForeground(Color.black);
c.gridy = 2;
panel.add(loadedType, c);
timeLabel = new JLabel("");
c.gridy = 3;
panel.add(timeLabel, c);
getContentPane().add(panel, "South");
// Change page based on text field
textField.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
String url = textField.getText();
try {
// Check if the new page and the old
// page are the same.
URL newURL = new URL(url);
URL loadedURL = pane.getPage();
if (loadedURL != null && loadedURL.sameFile(newURL)) {
return;
}
// Try to display the page
textField.setEnabled(false); // Disable input
textField.paintImmediately(0, 0, textField.getSize().width,
textField.getSize().height);
setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR));
// Busy cursor
loadingState.setText("Loading...");
loadingState.paintImmediately(0, 0,
loadingState.getSize().width, loadingState
.getSize().height);
loadedType.setText("");
loadedType.paintImmediately(0, 0,
loadedType.getSize().width,
loadedType.getSize().height);
timeLabel.setText("");
timeLabel.paintImmediately(0, 0, timeLabel.getSize().width,
timeLabel.getSize().height);
startTime = System.currentTimeMillis();
// Choose the loading method
if (onlineLoad.isSelected()) {
// Usual load via setPage
pane.setPage(url);
loadedType.setText(pane.getContentType());
} else {
pane.setContentType("text/html");
loadedType.setText(pane.getContentType());
if (loader == null) {
loader = new HTMLDocumentLoader();
}
HTMLDocument doc = loader.loadDocument(new URL(url));
loadComplete();
pane.setDocument(doc);
displayLoadTime();
}
} catch (Exception e) {
System.out.println(e);
JOptionPane.showMessageDialog(pane, new String[] {
"Unable to open file", url }, "File Open Error",
JOptionPane.ERROR_MESSAGE);
loadingState.setText("Failed");
textField.setEnabled(true);
setCursor(Cursor.getDefaultCursor());
}
}
});
// Listen for page load to complete
pane.addPropertyChangeListener(new PropertyChangeListener() {
public void propertyChange(PropertyChangeEvent evt) {
if (evt.getPropertyName().equals("page")) {
loadComplete();
displayLoadTime();
}
}
});
}
public void loadComplete() {
loadingState.setText("Page loaded.");
textField.setEnabled(true); // Allow entry of new URL
setCursor(Cursor.getDefaultCursor());
}
public void displayLoadTime() {
double loadingTime = ((double) (System.currentTimeMillis() - startTime)) / 1000d;
timeLabel.setText(loadingTime + " seconds");
}
public static void main(String[] args) {
try {
UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
} catch (Exception evt) {}
JFrame f = new EditorPaneExample9();
f.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent evt) {
System.exit(0);
}
});
f.setSize(500, 400);
f.setVisible(true);
}
static final String spaces = " ";
static final String LOAD_TIME = "Load time: ";
private JCheckBox onlineLoad;
private HTMLDocumentLoader loader;
private JLabel loadingState;
private JLabel timeLabel;
private JLabel loadedType;
private JTextField textField;
private JEditorPane pane;
private long startTime;
}
class HTMLDocumentLoader {
public HTMLDocument loadDocument(HTMLDocument doc, URL url, String charSet)
throws IOException {
doc.putProperty(Document.StreamDescriptionProperty, url);
/*
* This loop allows the document read to be retried if the character
* encoding changes during processing.
*/
InputStream in = null;
boolean ignoreCharSet = false;
for (;;) {
try {
// Remove any document content
doc.remove(0, doc.getLength());
URLConnection urlc = url.openConnection();
in = urlc.getInputStream();
Reader reader = (charSet == null) ? new InputStreamReader(in)
: new InputStreamReader(in, charSet);
HTMLEditorKit.Parser parser = getParser();
HTMLEditorKit.ParserCallback htmlReader = getParserCallback(doc);
parser.parse(reader, htmlReader, ignoreCharSet);
htmlReader.flush();
// All done
break;
} catch (BadLocationException ex) {
// Should not happen - throw an IOException
throw new IOException(ex.getMessage());
} catch (ChangedCharSetException e) {
// The character set has changed - restart
charSet = getNewCharSet(e);
// Prevent recursion by suppressing further exceptions
ignoreCharSet = true;
// Close original input stream
in.close();
// Continue the loop to read with the correct encoding
}
}
return doc;
}
public HTMLDocument loadDocument(URL url, String charSet)
throws IOException {
return loadDocument((HTMLDocument) kit.createDefaultDocument(), url,
charSet);
}
public HTMLDocument loadDocument(URL url) throws IOException {
return loadDocument(url, null);
}
// Methods that allow customization of the parser and the callback
public synchronized HTMLEditorKit.Parser getParser() {
if (parser == null) {
try {
Class c = Class
.forName("javax.swing.text.html.parser.ParserDelegator");
parser = (HTMLEditorKit.Parser) c.newInstance();
} catch (Throwable e) {
}
}
return parser;
}
public synchronized HTMLEditorKit.ParserCallback getParserCallback(
HTMLDocument doc) {
return doc.getReader(0);
}
protected String getNewCharSet(ChangedCharSetException e) {
String spec = e.getCharSetSpec();
if (e.keyEqualsCharSet()) {
// The event contains the new CharSet
return spec;
}
// The event contains the content type
// plus ";" plus qualifiers which may
// contain a "charset" directive. First
// remove the content type.
int index = spec.indexOf(";");
if (index != -1) {
spec = spec.substring(index + 1);
}
// Force the string to lower case
spec = spec.toLowerCase();
StringTokenizer st = new StringTokenizer(spec, " \t=", true);
boolean foundCharSet = false;
boolean foundEquals = false;
while (st.hasMoreTokens()) {
String token = st.nextToken();
if (token.equals(" ") || token.equals("\t")) {
continue;
}
if (foundCharSet == false && foundEquals == false
&& token.equals("charset")) {
foundCharSet = true;
continue;
} else if (foundEquals == false && token.equals("=")) {
foundEquals = true;
continue;
} else if (foundEquals == true && foundCharSet == true) {
return token;
}
// Not recognized
foundCharSet = false;
foundEquals = false;
}
// No charset found - return a guess
return "8859_1";
}
protected static HTMLEditorKit kit;
protected static HTMLEditorKit.Parser parser;
static {
kit = new HTMLEditorKit();
}
}
Related examples in the same category
