applicationapplet.java

java高级使用教程 全书一共分六章

// ApplicationApplet - run an Application in an Applet
//
// 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.

package Acme;

import java.applet.*;
import java.awt.*;
import java.io.*;

/// Run an Application in an Applet.
// <P>
// This applet lets any command-line application that uses a specially-enhanced
// main() routine automatically run in a web browser or appletviewer.
// Here's an example:
// <BLOCKQUOTE>
// <APPLET WIDTH=400 HEIGHT=150 CODEBASE="/resources/classes" CODE="Acme.ApplicationApplet"><PARAM NAME="bgcolor" VALUE="#99cc99">
// <PARAM NAME="class" VALUE="WebList">
// <PARAM NAME="args" VALUE="http://www.acme.com/jef/flow/">
// </APPLET>
// </BLOCKQUOTE>
// That's a command-line application running right now in your own browser.
// <P>
// The applet takes two parameters:
// <DL>
// <DT> CLASS
// <DD> The name of the class to run - your Application's name.
// <DT> ARGS
// <DD> The arguments to pass to the Application.
// </DL>
// <P>
// <A HREF="/resources/classes/Acme/ApplicationApplet.java">Fetch the software.</A><BR>
// <A HREF="/resources/classes/Acme.tar.gz">Fetch the entire Acme package.</A>
// <P>
// For details on how to adapt your application so that it can be run by
// ApplicationApplet,
// @see Application

public class ApplicationApplet extends Applet implements Runnable
    {

    /// Applet info.
    public String getAppletInfo()
	{
	return getClass().getName() +
" - running via ApplicationApplet - Copyright (C) 1996 by Jef Poskanzer <[e-mail]>.  All rights reserved.";
	}

    /// Parameter info.
    public String[][] getParameterInfo()
	{
	String[][] info =
	    {
	    { "CLASS",	"Class",	"the application to load" },
	    { "ARGS",	"string",	"the argument list" },
	    };
	return info;
	}

    TextArea textArea = null;

    Application app = null;
    String[] args = null;

    /// Called when the applet is first created.  This could be overridden
    // by a subclass to define what application to run and what args to
    // give it.  This default version gets the application name and args
    // list from the parameters.  A sample overriding version:
    // <BLOCKQUOTE><PRE>
    // public void init()
    //     {
    //     app = new MyApp();   // make an instance of this application
    //     getArgs();           // get args from the applet parameters
    //     }
    // </PRE></BLOCKQUOTE>
    // Pretty simple.
    public void init()
	{
	Acme.GuiUtils.handleBgcolor( this );

	if ( textArea == null )
	    makeTextArea();

	String appName = getParameter( "CLASS" );
	if ( appName == null )
	    {
	    showStatus( "Missing CLASS parameter" );
	    return;
	    }
	// Hack to accomodate those who use file names instead of class names.
	if ( appName.endsWith( ".class" ) )
	    appName = appName.substring(
		0, appName.length() - 6 ).replace( '/', '.' );
	if ( appName.endsWith( ".java" ) )
	    appName = appName.substring(
		0, appName.length() - 5 ).replace( '/', '.' );

	try
	    {
	    app = (Application) Class.forName( appName ).newInstance();
	    }
	catch ( ClassNotFoundException e )
	    {
	    showStatus( "Class not found: " + appName );
	    }
	catch ( ClassCastException e )
	    {
	    showStatus( "Class cast problem: " + e.getMessage() );
	    }
	catch ( InstantiationException e )
	    {
	    showStatus( "Instantiation problem - " + e.getMessage() );
	    }
	catch ( IllegalAccessException e )
	    {
	    showStatus( "Illegal class access - " + e.getMessage() );
	    }

	getArgs();
	}

    private void makeTextArea()
	{
	setLayout( new BorderLayout() );
	textArea = new TextArea();
	textArea.setEditable( false );
	textArea.setFont( new Font( "Courier", Font.PLAIN, 10 ) );
	add( "Center", textArea );
	validate();
	}
    
    /// Get the ARGS parameter and parse it into an array of Strings.
    public void getArgs()
	{
	String argList = getParameter( "ARGS" );
	if ( argList == null )
	    args = new String[0];
	else
	    args = Acme.Utils.splitStr( argList );
	}

    Thread thread = null;

    /// Called when the applet should start itself.
    public void start()
	{
        if ( thread == null )
            {
            // Start the thread.
            thread = new Thread(this);
            thread.start();
            }
	}

    /// Called when the applet should stop itself.
    public void stop()
	{
        if ( thread != null )
            {
	    // Stop the thread.
            thread.stop();
            thread = null;
            }
	}

    /// This is the part of Runnable that we implement - the routine that
    // gets called when the thread is started.
    public void run()
	{
	if ( textArea == null )
	    makeTextArea();
	if ( app == null )
	    {
	    showStatus( "No application defined" );
	    return;
	    }
	if ( args == null )
	    {
	    showStatus( "No arguments defined" );
	    return;
	    }

	InputStream in = new NullInputStream();
	PrintStream out = new APrintStream(
	    new TextcompOutputStream( textArea ) );

	String appName = app.getClass().getName();
	showStatus( appName + " running..." );
	out.println( "% " + appName + " " + Acme.Utils.flattenStrarr( args ) );
	app.compat( args, in, out, out );
	out.print( "% " );
	showStatus( appName + " done." );
	}

    /// Main program, so we can run as an application too.
    public static void main( String[] args )
	{
	new MainFrame( new ApplicationApplet(), args, 400, 500 );
	}

    }