mainframemodified.java

java高级使用教程 全书一共分六章

// MainFrameModified - a modified version of MainFrame, which can run an 
// Applet as an application
//
// Modified by Jason Hunter <[e-mail]> to fix bugs and optimize
// for use with servlets (1998).
//
// Copyright (C) 1996 by Jef Poskanzer <[e-mail]>.  All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
// OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
// OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
// SUCH DAMAGE.
//
// Visit the ACME Labs Java page for up-to-date versions of this and other
// fine Java utilities: http://www.acme.com/java/

package Acme;

import java.applet.*;
import java.awt.*;
import java.awt.image.*;
import java.net.*;
import java.io.*;
import java.util.*;

/// Run an Applet as an application.
// <P>
// Using this class you can add a trivial main program to any Applet
// and run it directly, as well as from a browser or the appletviewer.
// And unlike some versions of this concept, MainFrame implements both
// images and sound.
// <P>
// Sample main program:
// <BLOCKQUOTE><PRE>
// public static void main( String[] args )
//     {
//     new Acme.MainFrame( new ThisApplet(), args, 400, 400 );
//     }
// </PRE></BLOCKQUOTE>
// The only methods you need to know about are the constructors.
// <P>
// You can specify Applet parameters on the command line, as name=value.
// For instance, the equivalent of:
// <BLOCKQUOTE><PRE>
// &lt;PARAM NAME="pause" VALUE="200"&gt;
// </PRE></BLOCKQUOTE>
// would just be:
// <BLOCKQUOTE><PRE>
// pause=200
// </PRE></BLOCKQUOTE>
// You can also specify three special parameters:
// <BLOCKQUOTE><PRE>
// width=N          Width of the Applet.
// height=N         Height of the Applet.
// barebones=true   Leave off the menu bar and status area.
// </PRE></BLOCKQUOTE>
// <P>
// <A HREF="/resources/classes/Acme/MainFrame.java">Fetch the software.</A><BR>
// <A HREF="/resources/classes/Acme.tar.Z">Fetch the entire Acme package.</A>

public class MainFrameModified extends Frame
    implements Runnable, AppletStub, AppletContext
    {

    private String[] args = null;
    private static int instances = 0;
    private String name;
    private boolean barebones = false;
    private Applet applet;
    private Label label = null;
    private Dimension appletSize;

    private String PARAM_PROP_PREFIX = null;

    /// Constructor with everything specified.
    public MainFrameModified(
	Applet applet, String[] args, int width, int height )
	{
	build( applet, args, width, height );
	}

    /// Constructor with no default width/height.
    public MainFrameModified( Applet applet, String[] args )
	{
	build( applet, args, -1, -1 );
	}

    /// Constructor with no arg parsing.
    public MainFrameModified( Applet applet, int width, int height )
	{
	build( applet, null, width, height );
	}

    // Internal constructor routine.
    private void build(
	Applet applet, String[] args, int width, int height )
	{
	++instances;
	this.applet = applet;
	this.args = args;
	applet.setStub( this );
	name = applet.getClass().getName();
	setTitle( name );

        // Choose a unique parameter property prefix.
        PARAM_PROP_PREFIX = "parameter." + hashCode() + ".";

	// Set up properties.
	Properties props = System.getProperties();
	props.put( "browser", "Acme.MainFrame" );
	props.put( "browser.version", "11jul96" );
	props.put( "browser.vendor", "Acme Laboratories" );
	props.put( "browser.vendor.url", "http://www.acme.com/" );

	// Turn args into parameters by way of the properties list.
	if ( args != null )
	    parseArgs( args, props );

	// If width and height are specified in the parameters, override
	// the compiled-in values.
	String widthStr = getParameter( "width" );
	if ( widthStr != null )
	    width = Integer.parseInt( widthStr );
	String heightStr = getParameter( "height" );
	if ( heightStr != null )
	    height = Integer.parseInt( heightStr );

	// Were width and height specified somewhere?
	if ( width == -1 || height == -1 )
	    {
	    System.err.println( "Width and height must be specified." );
	    return;
	    }

	// Do we want to run bare-bones?
	String bonesStr = getParameter( "barebones" );
	if ( bonesStr != null && bonesStr.equals( "true" ) )
	    barebones = true;

	if ( ! barebones )
	    {
	    // Make menu bar.
	    MenuBar mb = new MenuBar();
	    Menu m = new Menu( "Applet" );
	    m.add( new MenuItem( "Restart" ) );
	    m.add( new MenuItem( "Clone" ) );
	    m.add( new MenuItem( "Close" ) );
	    m.add( new MenuItem( "Quit" ) );
	    mb.add( m );
	    setMenuBar( mb );
	    }

	// Lay out components.
	setLayout( new BorderLayout() );
	add( "Center", applet );
	if ( ! barebones )
	    {
	    Panel borderPanel =
		new Acme.Widgets.BorderPanel( Acme.Widgets.BorderPanel.RAISED );
	    borderPanel.setLayout( new BorderLayout() );
	    label = new Label( "" );
	    borderPanel.add( "Center", label );
	    add( "South", borderPanel );
	    }

	// Set up size.
	pack();
	validate();
	appletSize = applet.size();
	applet.resize( width, height );
	//show();

	// Start a separate thread to call the applet's init() and start()
	// methods, in case they take a long time.
	//(new Thread( this )).start();
        run();
	}
    
    // Turn command-line arguments into Applet parameters, by way of the
    // properties list.
    private void parseArgs( String[] args, Properties props )
	{
	for ( int i = 0; i < args.length; ++i )
	    {
	    String arg = args[i];
	    int ind = arg.indexOf( '=' );
	    if ( ind == -1 )
		props.put( PARAM_PROP_PREFIX + arg.toLowerCase(), "" );
	    else
		props.put(
		    PARAM_PROP_PREFIX + arg.substring( 0, ind ).toLowerCase(),
		    arg.substring( ind + 1 ) );
	    }
	}

    /// Event handler for the menu bar.
    public boolean handleEvent( Event evt )
	{
	switch ( evt.id )
	    {
	    case Event.ACTION_EVENT:
	    if ( evt.arg.equals( "Restart" ) )
		{
		applet.stop();
		applet.destroy();
		Thread thread = new Thread( this );
		thread.start();
		}
	    else if ( evt.arg.equals( "Clone" ) )
		{
		try
		    {
		    new MainFrameModified(
			(Applet) applet.getClass().newInstance(), args,
			appletSize.width, appletSize.height );
		    }
		catch ( IllegalAccessException e )
		    {
		    showStatus( e.getMessage() );
		    }
		catch ( InstantiationException e )
		    {
		    showStatus( e.getMessage() );
		    }
		}
	    else if ( evt.arg.equals( "Close" ) )
		{
		hide();
		remove( applet );
		applet.stop();
		applet.destroy();
		if ( label != null )
		    remove( label );
		dispose();
		--instances;
		if ( instances == 0 )
		    System.exit( 0 );
		}
	    else if ( evt.arg.equals( "Quit" ) )
		System.exit( 0 );
	    break;

	    case Event.WINDOW_DESTROY:
	    System.exit( 0 );
	    break;
	    }
	return super.handleEvent( evt );
	}
    

    // Methods from Runnable.

    /// Separate thread to call the applet's init() and start() methods.
    public void run()
	{
	showStatus( name + " initializing..." );
	applet.init();
	validate();
	showStatus( name + " starting..." );
	applet.start();
	validate();
	showStatus( name + " running..." );
	}


    // Methods from AppletStub.

    public boolean isActive()
	{
	return true;
	}
    
    public URL getDocumentBase()
	{
	// Returns the current directory.
	String dir = System.getProperty( "user.dir" );
	String urlDir = dir.replace( File.separatorChar, '/' );
	try
	    {
	    return new URL( "file:" + urlDir + "/");
	    }
	catch ( MalformedURLException e )
	    {
	    return null;
	    }
	}
    
    public URL getCodeBase()
	{
	// Hack: loop through each item in CLASSPATH, checking if
	// the appropriately named .class file exists there.  But
	// this doesn't account for .zip files.
	String path = System.getProperty( "java.class.path" );
	Enumeration st = new StringTokenizer( path, File.pathSeparator );
	while ( st.hasMoreElements() )
	    {
	    String dir = (String) st.nextElement();
            String transname = name.replace( '.', File.separatorChar );
	    String filename = dir + File.separatorChar + transname + ".class";
	    File file = new File( filename );
	    if ( file.exists() )
		{
		String urlDir = dir.replace( File.separatorChar, '/' );
		try
		    {
		    return new URL( "file:" + urlDir + "/" );
		    }
		catch ( MalformedURLException e )
		    {
		    return null;
		    }
		}
	    }
        try
            {
	      return new URL("http://localhost/");
            }
        catch (MalformedURLException e)
            {
              return null;
            }
	}
    
    public String getParameter( String name )
	{
	// Return a parameter via the munged names in the properties list.
	return System.getProperty( PARAM_PROP_PREFIX + name.toLowerCase() );
	}
    
    public void appletResize( int width, int height )
	{
	// Change the frame's size by the same amount that the applet's
	// size is changing.
	Dimension frameSize = size();
	frameSize.width += width - appletSize.width;
	frameSize.height += height - appletSize.height;
	resize( frameSize );
	appletSize = applet.size();
	}

    public AppletContext getAppletContext()
	{
	return this;
	}
    

    // Methods from AppletContext.

    public AudioClip getAudioClip( URL url )
	{
	// This is an internal undocumented routine.  However, it
	// also provides needed functionality not otherwise available.
	// I suspect that in a future release, JavaSoft will add an
	// audio content handler which encapsulates this, and then
	// we can just do a getContent just like for images.
	return new sun.applet.AppletAudioClip( url );
	}

    public Image getImage( URL url )
	{
	Toolkit tk = Toolkit.getDefaultToolkit();
	try
	    {
	    ImageProducer prod = (ImageProducer) url.getContent();
	    return tk.createImage( prod );
	    }
	catch ( IOException e )
	    {
	    return null;
	    }
	}
    
    public Applet getApplet( String name )
	{
	// Returns this Applet or nothing.
	if ( name.equals( this.name ) )
	    return applet;
	return null;
	}
    
    public Enumeration getApplets()
	{
	// Just yields this applet.
	Vector v = new Vector();
	v.addElement( applet );
	return v.elements();
	}
    
    public void showDocument( URL url )
	{
	// Ignore.
	}
    
    public void showDocument( URL url, String target )
	{
	// Ignore.
	}
    
    public void showStatus( String status )
	{
	if ( label != null )
	    label.setText( status );
	}

    }