webbrowser.java

Examples From Java Examples in a Nutshell, 2nd Edition 书中的源码

	    // If we can go back, then enable the Back action
	    if (currentHistoryPage > 0) backAction.setEnabled(true);
	}
    }

    /** Like displayPage(URL), but takes a string instead */
    public void displayPage(String href) {
	try {
	    displayPage(new URL(href));
	}
	catch (MalformedURLException ex) {
	    messageLine.setText("Bad URL: " + href);
	}
    }

    /** Allow the user to choose a local file, and display it */
    public void openPage() {
	// Lazy creation: don't create the JFileChooser until it is needed
	if (fileChooser == null) {
	    fileChooser = new JFileChooser();
	    // This javax.swing.filechooser.FileFilter displays only HTML files
	    FileFilter filter = new FileFilter() {
		    public boolean accept(File f) {
			String fn = f.getName();
			if (fn.endsWith(".html") || fn.endsWith(".htm"))
			    return true;
			else return false;
		    }
		    public String getDescription() { return "HTML Files"; }
		};
	    fileChooser.setFileFilter(filter);
	    fileChooser.addChoosableFileFilter(filter);
	}

	// Ask the user to choose a file.
	int result = fileChooser.showOpenDialog(this);
	if (result == JFileChooser.APPROVE_OPTION) {
	    // If they didn't click "Cancel", then try to display the file.
	    File selectedFile = fileChooser.getSelectedFile();
	    String url = "file://" + selectedFile.getAbsolutePath();
	    displayPage(url);
	}
    }

    /** Go back to the previously displayed page. */
    public void back() {
	if (currentHistoryPage > 0)  // go back, if we can
	    visit((URL)history.get(--currentHistoryPage));
	// Enable or disable actions as appropriate
	backAction.setEnabled((currentHistoryPage > 0));
	forwardAction.setEnabled((currentHistoryPage < history.size()-1));
    }

    /** Go forward to the next page in the history list */
    public void forward() {
	if (currentHistoryPage < history.size()-1)  // go forward, if we can
	    visit((URL)history.get(++currentHistoryPage));
	// Enable or disable actions as appropriate
	backAction.setEnabled((currentHistoryPage > 0));
	forwardAction.setEnabled((currentHistoryPage < history.size()-1));
    }

    /** Reload the current page in the history list */
    public void reload() {
	if (currentHistoryPage != -1)
	    visit((URL)history.get(currentHistoryPage));
    }

    /** Display the page specified by the "home" property */
    public void home() { displayPage(getHome()); }

    /** Open a new browser window */
    public void newBrowser() {
	WebBrowser b = new WebBrowser();
	b.setSize(this.getWidth(), this.getHeight());
	b.setVisible(true);
    }

    /**
     * Close this browser window.  If this was the only open window,
     * and exitWhenLastBrowserClosed is true, then exit the VM
     **/
    public void close() {
	this.setVisible(false);             // Hide the window
	this.dispose();                     // Destroy the window
	synchronized(WebBrowser.class) {    // Synchronize for thread-safety
	    WebBrowser.numBrowserWindows--; // There is one window fewer now
	    if ((numBrowserWindows==0) && exitWhenLastWindowClosed)
		System.exit(0);             // Exit if it was the last one
	}
    }
       
    /**
     * Exit the VM.  If confirm is true, ask the user if they are sure.
     * Note that showConfirmDialog() displays a dialog, waits for the user,
     * and returns the user's response (i.e. the button the user selected).
     **/
    public void exit(boolean confirm) {
	if (!confirm ||
	    (JOptionPane.showConfirmDialog(this,  // dialog parent
	         /* message to display */  "Are you sure you want to quit?",
		 /* dialog title */	   "Really Quit?",
		 /* dialog buttons */	   JOptionPane.YES_NO_OPTION) == 
	     JOptionPane.YES_OPTION))  // If Yes button was clicked
	    System.exit(0);
    }

    /**
     * Print the contents of the text pane using the java.awt.print API
     * Note that this API does not work efficiently in Java 1.2
     * All the hard work is done by the PrintableDocument class.
     **/
    public void print() {
	// Get a PrinterJob object from the system
	PrinterJob job = PrinterJob.getPrinterJob();
	// This is the object that we are going to print
	PrintableDocument pd = new PrintableDocument(textPane);
	// Tell the PrinterJob what we want to print
	job.setPageable(pd);
	// Display a print dialog, asking the user what pages to print, what
	// printer to print to, and giving the user a chance to cancel.
	if (job.printDialog()) {  // If the user did not cancel
	    try { job.print(); }  // Start printing!
	    catch(PrinterException ex) {  // display errors nicely
		messageLine.setText("Couldn't print: " + ex.getMessage());
	    }
	}
    }

    /** 
     * This method implements HyperlinkListener.  It is invoked when the user
     * clicks on a hyperlink, or move the mouse onto or off of a link
     **/
    public void hyperlinkUpdate(HyperlinkEvent e) {
	HyperlinkEvent.EventType type = e.getEventType();  // what happened?
	if (type == HyperlinkEvent.EventType.ACTIVATED) {     // Click!
	    displayPage(e.getURL());   // Follow the link; display new page
	}
	else if (type == HyperlinkEvent.EventType.ENTERED) {  // Mouse over!
	    // When mouse goes over a link, display it in the message line
	    messageLine.setText(e.getURL().toString());  
	}
	else if (type == HyperlinkEvent.EventType.EXITED) {   // Mouse out!
	    messageLine.setText(" ");  // Clear the message line
	}
    }

    /**
     * This method implements java.beans.PropertyChangeListener.  It is 
     * invoked whenever a bound property changes in the JEditorPane object.
     * The property we are interested in is the "page" property, because it
     * tells us when a page has finished loading.
     **/
    public void propertyChange(PropertyChangeEvent e) {
	if (e.getPropertyName().equals("page")) // If the page property changed
	    stopAnimation();              // Then stop the loading... animation
    }

    /**
     * The fields and methods below implement a simple animation in the
     * web browser message line; they are used to provide user feedback
     * while web pages are loading.
     **/
    String animationMessage;  // The "loading..." message to display
    int animationFrame = 0;   // What "frame" of the animation are we on
    String[] animationFrames = new String[] {  // The content of each "frame"
	"-", "\\", "|", "/", "-", "\\", "|", "/", 
	",", ".", "o", "0", "O", "#", "*", "+"
    };

    /** This object calls the animate() method 8 times a second */
    javax.swing.Timer animator =
	new javax.swing.Timer(125, new ActionListener() {
		public void actionPerformed(ActionEvent e) { animate(); }
	    });

    /** Display the next frame. Called by the animator timer */
    void animate() {
	String frame = animationFrames[animationFrame++];    // Get next frame
	messageLine.setText(animationMessage + " " + frame); // Update msgline
	animationFrame = animationFrame % animationFrames.length;
    }

    /** Start the animation.  Called by the visit() method. */
    void startAnimation(String msg) {
	animationMessage = msg;     // Save the message to display
	animationFrame = 0;         // Start with frame 0 of the animation
	animator.start();           // Tell the timer to start firing.
    }

    /** Stop the animation.  Called by propertyChanged() method. */
    void stopAnimation() {       
	animator.stop();            // Tell the timer to stop firing events
	messageLine.setText(" ");   // Clear the message line
    }
}