simplelinklistener.java

java swing 开发代码

// SimpleLinkListener.java
// A hyperlink listener for use with JEditorPane.  This
// listener changes the cursor over hyperlinks based on enter/exit
// events and also loads a new page when a valid hyperlink is clicked.
//
package	jswing.ch23;


import java.io.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.text.html.*;

public class SimpleLinkListener implements HyperlinkListener {

  private JEditorPane pane;       // The pane we're using to display HTML

  private JTextField  urlField;   // An optional text field for showing
                                  // the current URL being displayed

  private JLabel statusBar;       // An optional label for showing where
                                  // a link would take you

  public SimpleLinkListener(JEditorPane jep, JTextField jtf, JLabel jl) {
    pane = jep;
    urlField = jtf;
    statusBar = jl;
  }

  public SimpleLinkListener(JEditorPane jep) {
    this(jep, null, null);
  }

  public void hyperlinkUpdate(HyperlinkEvent he) {
    HyperlinkEvent.EventType type = he.getEventType();
    if (type == HyperlinkEvent.EventType.ENTERED) {
      // Enter event.  Fill in the status bar.
      if (statusBar != null) {
        statusBar.setText(he.getURL().toString());
      }
    }
    else if (type == HyperlinkEvent.EventType.EXITED) {
      // Exit event.  Clear the status bar.
      if (statusBar != null) {
        statusBar.setText(" "); // Must be a space or it disappears
      }
    }
    else if (type == HyperlinkEvent.EventType.ACTIVATED) {
      // Jump event.  Get the URL, and, if it's not null, switch to that
      // page in the main editor pane and update the "site url" label.
      if (he instanceof HTMLFrameHyperlinkEvent) {
        // Ahh, frame event; handle this separately.
        HTMLFrameHyperlinkEvent  evt = (HTMLFrameHyperlinkEvent)he;
        HTMLDocument doc = (HTMLDocument)pane.getDocument();
        doc.processHTMLFrameHyperlinkEvent(evt);
      } else {
        try {
          pane.setPage(he.getURL());
          if (urlField != null) {
            urlField.setText(he.getURL().toString());
          }
        }
        catch (FileNotFoundException fnfe) {
          pane.setText("Could not open file: <tt>" + he.getURL() + 
                       "</tt>.<hr>");
        }
        catch (Exception e) {
          e.printStackTrace();
        }
      }
    }
  }
}