CS596: Doc 34, Applets

	CS 596 Java Programming Fall Semester, 1998 Applets
	To Lecture Notes Index © 1998, All Rights Reserved, SDSU & Roger Whitney San Diego State University -- This page last updated 21-Dec-98

Contents of Doc 34, Applets

References

First Applet

Applet Tags

Applet Methods

Basic Methods Example

Communication with the Browser

Displaying Items in the Browser

Applet-Applet Communication

Images

Applet as Application

The Browser Mess & Java Plug-in

References

Graphic Java 1.2 Volume I: AWT 3 ^rd Edition, Geary, Chapter 2 (pp. 15-24)

Core Java 1.1, Volume 1 - Fundamentals , Horstmann, Cornell, Prentice Hall, Chapter 10 (pp 463-509)

On-line JDK 1.2 API Documentation


S-dec7 12mins, Q-dec10 7mins Doc 34, Applets Slide # 2

First Applet

The HTML

<HTML>
<HEAD>
   <TITLE>HelloApplet</TITLE>
</HEAD>
<BODY>
<HR>
This is the first Applet<P>
<APPLET
   code="HelloApplet.class" width=100 height=100>
</APPLET><BR>
The End
<HR>
</BODY>
</HTML>

The Java Code

import java.awt.*;
import java.applet.Applet;
public class HelloApplet extends Applet
{
   public void init() {
      repaint();
   }
   
   public void paint( Graphics g ) {
      g.drawString( "Hello World!", 30, 30 );
   }
}
S-dec7 10secs Doc 34, Applets Slide # 3

Output Note: all examples are done using the applet viewer

Running the Example - AppletViewer

The good way to view and debug applets is with the appletviewer. See http://www.sdsu.edu/doc/jdk1.1/docs/tooldocs/solaris/appletview.html or http://www.eli.sdsu.edu/doc/jdk1.2/tooldocs/solaris/appletviewer.html for information about using the appletviewer. The documentation at http://java.sun.com/products/jdk1.2/docs/tooldocs/solaris/appletviewer.html has more information.

   appletviewer URLOfTheHTMLFile

will display applet referred to in the HTML.


S-dec7 2mins, Q-dec10 2mins Doc 34, Applets Slide # 4

Running the Example - BrowserFile You can use the open file menu item on either Internet Explorer or Netscape's browser (Navigator or Communicator) to open the html file. This will display both the html and the applet. Note that when loaded in a browser, you have to quit then restart the browser to reload browser.

From Web Server

You can also load the applet from a web server. See http://www-rohan.sdsu.edu/pagecreate.html for instructions on how to publish a web page on rohan. Once you have made the html file that refers to the applet available, just access the page via a Java enabled browser.

Classpath and Applets When you run an Applet in a browser, the browser uses its own version of Java. The browser does not use your classpath. This means you must make sure that all the classes used by your applet are either in the JDK supported by the browser, or downloaded with the applet. For security reasons an applet can not download classes in the java.* packages. In JDK 1.0 and 1.1, the appletviewer did use your classpath. This means that an applet using classes in your classpath would work when tested in the appletviewer but not in a browser. The appletviewer with the JDK 1.2 FCS (FCS = first customer ship, Sun's way of telling specifying an actual release from a beta) does not use your classpath.

Applets & Browsers on Rohan As of December 6, 1998, none of the versions of Netscape's browsers on rohan are fully complaint with JDK 1.1.


S-dec7 31secs Doc 34, Applets Slide # 5

Applet Tags

See: http://java.sun.com/products/jdk/1.2/docs/tooldocs/appletviewertags.html for more information about the tags supported by the appletviewer.

applet The applet tag is the original HTML 3.2 tag for embedding an applet in an HTML page

<APPLET
   ARCHIVE="yourJar1.jar"
   CODE="yourClass.class"
   OBJECT="serializedObjectOrJavaBean"
   CODEBASE="classFileDirectory"
   WIDTH="pixelWidth"
   HEIGHT="pixelHeight"
   NAME="appletName"
   HSPACE="n", 
   VSPACE="n"
   ALIGN=left | right | top | middle | bottom
   >
   <PARAM NAME="..." VALUE="...">
    ...
   alternate-text
</APPLET>

Only one of CODE or OBJECT is specified. The optional CODEBASE attribute supplies a relative URL that specifies the location of the applet class. The optional ARCHIVE indicated a jar file(s) search for files. PARAM tags supply argument values for applet parameters. HSPACE and VSPACE control horizontal and vertical spacing around the applet. We will see examples of these options later.


Doc 34, Applets Slide # 6

object
The object tag is the HTML 4.0 tag for embedding applets and multi-media objects into an HTML page. In HTML 4.0, the applet tag is deprecated. The object tag is also an Internet Explorer 4.x extension to HTML 3.2 which allows IE to run a Java applet using the latest Java plug-in from Sun. The object tag is the HTML 4.0 tag for embedding applets and multi-media objects into an HTML page. It is also an Internet Explorer 4.x extension to HTML 3.2 which allows IE to run a Java applet using the latest Java plug-in from Sun. Later we will cover more about this tag and the plug-in.

<OBJECT
   WIDTH="pixelWidth"
   HEIGHT="pixelHeight"
   >
   <PARAM NAME="code" VALUE="yourClass.class">
   <PARAM NAME="object" VALUE="serializedObjectOrJavaBean">
   <PARAM NAME="codebase" VALUE="classFileDirectory">
    ...
   alternate-text
</OBJECT>


Doc 34, Applets Slide # 7

embed
The embed tag is the Netscape extension to HTML 3.2 that allows embedding an applet or a multimedia object in an HTML page. It allows a Netscape 4.x browser (which supports HTML 3.2) to run a Java applet using the latest Java plug-in from Sun. Later we will cover more about this tag and the plug-in.

<EMBED
   CODE="yourClass.class"
   OBJECT="serializedObjectOrJavaBean"
   CODEBASE="classFileDirectory"
   WIDTH="pixelWidth"
   HEIGHT="pixelHeight"
   >
    ...
</EMBED>
S-dec7 4mins Doc 34, Applets Slide # 8

Applet Methods

destroy()
getAppletContext()
getAppletInfo()
getAudioClip(URL)
getAudioClip(URL, String)
getCodeBase()
getDocumentBase()
getImage(URL)
getImage(URL, String)
getLocale()
getParameter(String)

getParameterInfo()
init()
isActive()
play(URL)
play(URL, String)
resize(Dimension)
resize(int, int)
setStub(AppletStub)
showStatus(String)
start()
stop()

init()

Called by the browser or applet viewer when an applet is loaded into the system. This is used to replace the functionality of constructor. This method is called only once in the life of an applet object.

start()

Called by the browser or applet viewer to inform an applet that it should start its execution. It is called automatically after the init() method is called. It is also called when the user returns to the page containing the applet, after viewing other pages. Start is often used to start threads and animation. This method can be called more than once in the life of an applet object.

stop()

Called by the browser or applet viewer to inform an applet that it should stop its execution. This is called when the user moves off to another page. Use this to stop animations, threads, and playing audio files. If you do not use animation, threads or audio files you normally don't need to implement stop().. This method can be called more than once in the life of an applet object.

destroy()

Called by the browser or applet viewer to inform this applet that it is being unloaded. Use this method to reclaim any non-memory-dependent destroy resources that it has allocated (like graphics contexts). This method is called only once in the life of an applet object.


S-dec7 1min, Q-dec10 9mins Doc 34, Applets Slide # 9

Basic Methods Example

This example just displays when the basic applet methods are run in an applet. The output is displayed in a TextArea. In order to save space on the slide, I will only display the applet part of the HTML. This does work with the applet viewer and broswers, although it is not proper HTML.
HTML

<APPLET 
      CODE="BasicEventApplet.class" WIDTH=300 HEIGHT=200>
</APPLET>

Java Code

import java.awt.*;
import java.applet.Applet;
public class BasicEventApplet extends Applet
{
   TextArea messages = new TextArea(8, 30);
   
   public BasicEventApplet() {
      messages.append( "Constructor\n" );
   }
         
   public void init() {
      add( messages ); 
      messages.append( "Init\n" );
   }
   
   public void start() { messages.append( "Start\n" ); }
   public void stop() { messages.append( "Stop\n" ); }
   public void destroy() { messages.append( "Destroy\n" ); }
   
   public void paint( Graphics g ) {messages.append( "Paint\n" ); }
}
S-dec7 4mins Doc 34, Applets Slide # 10

Output Note: all examples are done using the applet viewer


S-dec7 1min Doc 34, Applets Slide # 11

Alternative Text
Some browsers do not support applets. You should provide alternative text to be displayed in such browsers. The tag below provides such text.

<APPLET 
   CODE="BasicEventApplet.class" WIDTH=300 HEIGHT=200>
   Your browser does <B>not</B> support applets! So you can
   not use my great applet.
</APPLET>

Alignment There is some control over the alignment of the applet.

<APPLET 
   CODE="BasicEventApplet.class" WIDTH=300 HEIGHT=200
   ALIGN="right">
</APPLET>

left

Place the applet at the left margin of page, text to the left of the applet

right

Place the applet at the right margin of page, text to the right of the applet

top

Place the top of applet at the top of the current line

middle

Place the middle of applet with the baseline of the current line

bottom

Place the bottom of applet at the bottom of the text on the current line


S-dec7 2mins, Q-dec10 1min Doc 34, Applets Slide # 12

Applet Parameters

This example shows how to pass information to an applet from the html page. The getParameter() method will read arguments with the param tag. It also seems to read the width & height. The methods getAppletInfo() & getParameterInfo() are used by the applet viewer to provide the user with information about the applet.
HTML

<APPLET
   CODE="ParameterApplet.class" WIDTH=300 HEIGHT=200>
   <PARAM NAME="name" VALUE="Roger">
   <PARAM NAME="yourHeight" VALUE="5">
</APPLET>

Java Code

import java.awt.*;
import java.applet.Applet;
public class ParameterApplet extends Applet {
   TextArea messages = new TextArea(8, 20);
            
   public void init() {
      add( messages );
      String name = getParameter( "name" );
      int height = 
         Integer.valueOf (getParameter( "yourHeight" )).intValue();
      messages.append( "name: " + name + "\n" );
      messages.append( "height: " + height + "\n" ); }
   public String getAppletInfo() {
      return "This applet shows how to pass information" +
         " from the html document to the applet"; }
   
   public String[][] getParameterInfo() {
      return new String[][] {
         { "name" , "string", "your name" }, 
         { "yourHeight", "int" , "your height"}
      }; 
   }
}
Doc 34, Applets Slide # 13

Output Note: all examples are done using the applet viewer


S-dec7 2mins, Q-dec10 11mins Doc 34, Applets Slide # 14

Multiple Files

An applet may require more than one .class file, or it may require a sound file or image files. By default, all files are loaded from the same location as the .html file that refers to the applet. In the following example, the applet requires the file AnotherClass.class to run. It is downloaded from the same location as the .html file and the MultipleFilesApplet.class file.
HTML

<APPLET
   CODE="MultipleFilesApplet.class" WIDTH=300 HEIGHT=200>
</APPLET>

Java Code

import java.awt.*;
import java.applet.Applet;
public class MultipleFilesApplet extends Applet
{
   public void init() {
      repaint();
   }
   public void paint( Graphics display ) {
      AnotherClass test = new AnotherClass();
      display.drawString( test.name(), 20, 20 );
   }
}
public class AnotherClass {
   public String name() { 
      return "Roger";
   }
}
S-dec7 3mins Doc 34, Applets Slide # 15

JAR Files

The files required by an applet can be placed into a jar file. A jar file is a compressed file (zip algorithm) with a manifest (list of contents). This can speed up the transfer of the applet in two ways. First, the file is compressed. Second, if requires only one interaction with the web server to obtain all the needed files. The example below, shows how create and access a jar file for the applet on the previous slide. The jar file can contain images and sound.

The basic syntax for creating a jar file is:

jar -cf jarFileName.jar file1, file2, ..., fileN

where file1, ..., fileN are the files to put into the jar file. See the java tool documentation for more information about the jar command. See for example: http://java.sun.com/products/jdk/1.2/docs/tooldocs/solaris/jar.html. The following command creates the file myJar.jar for the example on the previous slide.

jar -cf myJar.jar AnotherClass.class MultipleFilesApplet.class

The following applet tag tells the browser/appleviewer to also look into the jar file myjar.jar to find any files needed by the applet. The jar file will be loaded from the same location as the html file. You can specify more than one jar file by separating the file names with commas: archive="jar1.jar, jar2.jar".

<APPLET
   ARCHIVE="myJar.jar"
   CODE="MultipleFilesApplet.class" WIDTH=300 HEIGHT=200>
</APPLET>
Doc 34, Applets Slide # 16

Size of Applet Area This example shows how to determine the applet's size.
HTML

<APPLET archive="AppletClasses.jar" 
   code="SizeApplet.class" width=100 height=100>
</APPLET>

Java Code

import java.awt.*;
import java.applet.Applet;
public class SizeApplet extends Applet
{
   public void init() {
      repaint();
   }
   
   public void paint( Graphics display ) {
      Dimension size = getSize();
      display.drawString( "height = " + size.height, 30, 30 );
      display.drawString( "width = " + size.width, 30, 50 );
      display.drawRect( 0, 0, size.width-1, size.height-1);
      }
}

Output Note: all examples are done using the applet viewer


S-dec7 3mins Doc 34, Applets Slide # 17

CodeBase Use the codebase tag to specify a location to find the files needed by the applet. You can specify the location relative to the location of the referencing .html file (document base) or give a full URL.

Specify Full URL Look for the .class files in the specified location

<APPLET
   CODEBASE= "http://www.eli.sdsu.edu/courses/fall98/cs596/notes/code"
   CODE="MultipleFilesApplet.class" WIDTH=300 HEIGHT=200>
</APPLET>

Relative Location Look for the .class files in the subdirectory "code" from the document base.

<APPLET
   CODEBASE= "code"
   CODE="MultipleFilesApplet.class" WIDTH=300 HEIGHT=200>
</APPLET>

With jar File

<APPLET
   CODEBASE= "code"
   ARCHIVE="myJar.jar"
   CODE="MultipleFilesApplet.class" WIDTH=300 HEIGHT=200>
</APPLET>
S-dec7 2mins Doc 34, Applets Slide # 18

Status Window
Some browsers have a "status window". In Netscape's browser, this is the status line at the bottom of the browser window. The showStatus() method places text in that window.


import java.awt.*;
import java.applet.Applet;
public class StatusApplet extends Applet
{
   public void paint( Graphics display) {
      showStatus( "Hi mom" );
   }   
}
Doc 34, Applets Slide # 19

Applets & AWT

An Applet is a subclass of Container and Panel. FlowLayout is the default layout manager for applets. We can add any AWT component to an applet we can add to a Panel. The example below shows adding buttons to an applet.
HTML

<APPLET archive="AppletClasses.jar" 
   code="ButtonApplet.class" width=100 height=100>
      <param name="name" value="Roger">
</APPLET>

Java Code

import java.awt.*;
import java.applet.Applet;
import java.awt.event.*;
public class  ButtonApplet  extends Applet {
   Button red = new Button( "Red" );
   Button blue = new Button( "Blue" );
   
   public void init( ) {
      add( red );
      add( blue );
      red.addActionListener( new ColorActionListener( Color.red) );
      blue.addActionListener( new ColorActionListener( Color.blue) );
   }
   class ColorActionListener implements ActionListener {
      Color backgroundColor;
      
      public ColorActionListener( Color aColor ) {
         backgroundColor = aColor;
      }
      public void actionPerformed( ActionEvent event ) {
         setBackground( backgroundColor );
         repaint();
      }
   }
}
Doc 34, Applets Slide # 20

Output Note: all examples are done using the applet viewer


Doc 34, Applets Slide # 21

Applets and Windows

You can open windows in an applet. Depending on the browser and the security measures taken, the window usually marked as untrusted. The user may be asked if they will allow the applet to open the window.
HTML

<APPLET archive="AppletClasses.jar" 
   code="WindowApplet.class" width=100 height=100>
</APPLET>

Java Code

import java.awt.*;
import java.applet.Applet;
import java.awt.event.*;
public class  WindowApplet  extends Applet {
   Button display = new Button( "Open" );
   Frame buttonWindow = new ButtonExample( 75, 75 );
   public void init( ) {
      add( display );
      
      display.addActionListener( new DisplayListener( ) );
   }
   class DisplayListener implements ActionListener {
      public void actionPerformed( ActionEvent event )  {
         if ( buttonWindow.isVisible() ) {
            display.setLabel( "Open" );
            buttonWindow.setVisible( false );
         } else {
            display.setLabel( "Close" );
            buttonWindow.setVisible( true );
         }
      }
   }
}
Doc 34, Applets Slide # 22

Applets and Windows Continued This is the window opened by the applet on the previous slide.

class  ButtonExample  extends Frame {
   Button red = new Button( "Red" );
   Button blue = new Button( "Blue" );
   
   public ButtonExample( int  widthInPixels, int heightInPixels ) {
      setTitle( "Button Example" );
      setSize( widthInPixels, heightInPixels );
      setLayout( new FlowLayout() );
      add( red );
      add( blue );
      
      red.addActionListener( new ColorActionListener( Color.red) );
      blue.addActionListener( new ColorActionListener( Color.blue) );
   }
   
   class ColorActionListener implements ActionListener {
      Color backgroundColor;
      
      public ColorActionListener( Color aColor ) {
         backgroundColor = aColor;
      }
      
      public void actionPerformed( ActionEvent event )  {
         setBackground( backgroundColor );
         repaint();      // Show effect of color change
      }
   }
}
Doc 34, Applets Slide # 23

Communication with the Browser

The AppletContext provides the ability for the applet to ask the browser to perform tasks for the applet.
AppletContext Methods

getApplet(String)
getApplets()
getAudioClip(URL)

getImage(URL)
showDocument(URL)
showDocument(URL, String)
showStatus(String)

Note that the methods: getAudioClip(), getImage(), showStatus() in the Applet class call the corresponding methods in the AppletContext.


S-dec7 3mins Doc 34, Applets Slide # 24

Displaying Items in the Browser

An applet can have the browser show pages.

import java.applet.*;
import java.net.URL;
import java.net.MalformedURLException;
public class ShowDocumentApplet extends Applet
{
   public void init( ) {
      try {
         URL wwwEli = new URL( "http://www.eli.sdsu.edu" );
         AppletContext myContext = getAppletContext();
         myContext.showDocument( wwwEli, "_blank");
      }
      catch (MalformedURLException punt ) {
      }
   }   
}

Values of Second Argument to showDocument

Argument	Meaning
"_self"	Show in the window and frame that contain the applet
"_parent"	Show in the parent frame. If the applet's frame has no parent, acts the same as "_self"
"_top"	Show in the topmost frame of the applet's window. If the applet's frame is the top-level, acts the same as "_self"
"_blank"	Show in a new unnamed top-level window.
name	Show in the frame or window named name. If name does not exist, create a new top-level window named name, and show the document in it


S-dec7 2mins Doc 34, Applets Slide # 25

Applet-Applet Communication

Applets on the same page can communicate with each other. The following applet demonstrates how to do this. The InfoBus provides a more general way of doing this. See http://java.sun.com/beans/infobus/index.html for more information.

HTML

<APPLET ARCHIVE="AppletClasses.jar" 
   CODE="Communication1Applet.class" WIDTH=100 HEIGHT=100>
</APPLET><BR>
<APPLET ARCHIVE="AppletClasses.jar" 
   CODE="Communication2Applet.class" WIDTH=100 HEIGHT=100 
   NAME="sam">
</APPLET>

Java Code

import java.applet.*;
import java.util.Enumeration;
import java.awt.Graphics;
import java.awt.event.*;
import java.awt.Button;
public class Communication2Applet extends Applet {
   String message = "Not set";
   
   public void paint( Graphics display ) {
      display.drawString( message, 20, 20 );
   }
   public void setMessage( String newMessage ) {
      message = newMessage;
      repaint();
   }
}


S-dec7 5mins Doc 34, Applets Slide # 26

Applet Communication Continued

public class Communication1Applet extends Applet {
   public void init( ) {
         AppletContext myContext = getAppletContext();
         Communication2Applet partner;
         partner = (Communication2Applet) myContext.getApplet( "sam" );
         partner.setMessage( "Hi mom" );
         
         Button doIt = new Button( "Do it" );
         add( doIt );
         doIt.addActionListener( new DoItListener() );
   }
   class DoItListener implements ActionListener {
      public void actionPerformed( ActionEvent event )  {
            Enumeration applets = getAppletContext().getApplets();
         while ( applets.hasMoreElements() ) {
            Object applet = applets.nextElement();
            if ( applet instanceof Communication2Applet ) 
               ((Communication2Applet) applet).setMessage( "Did it");
         }
      }
   }
}
Doc 34, Applets Slide # 27

Output Note: all examples are done using the applet viewer


S-dec9 5mins Doc 34, Applets Slide # 28

Images

HTML

<APPLET ARCHIVE="AppletClasses.jar" 
   CODE="ImageApplet.class" WIDTH=350 HEIGHT=100>
</APPLET>

Java Code

import java.awt.*;
import java.applet.Applet;
import java.awt.Image;
public class ImageApplet extends Applet{
   private Image ioStream;
   private String errorMessage = null;
   public void init() {
      try {
         ioStream = getImage( getCodeBase(), "IO1002.gif" );
         MediaTracker tracker = new MediaTracker( this );
         tracker.addImage( ioStream, 0 );
         tracker.waitForID( 0 );
         System.out.println("Ready" );
         repaint();
      }
      catch (InterruptedException netProblem ) {
         errorMessage = "Could not reach image";
      }
   }
   public void paint( Graphics display) {
      if ( errorMessage == null )
         display.drawImage( ioStream, 0, 0, this );
      else
         display.drawString( errorMessage, 10, 10 );
   }
}
Doc 34, Applets Slide # 29

Output Note: all examples are done using the applet viewer


S-dec9 4mins Doc 34, Applets Slide # 30

Applet as Application

The following class, modified from the text (page 22-23), runs an applet as an application. This class has problems.

import java.awt.*;
import java.applet.Applet;
import java.awt.event.*;
public class SimpleAppletApplication extends Frame {
   Applet appletApp;
   
   public SimpleAppletApplication( String windowTitle, 
                                    int width, int height, Applet anApplet ) {
      super( windowTitle );
      setSize( width, height );
      appletApp = anApplet;
      appletApp.init();
      add(  BorderLayout.CENTER, appletApp );
      
      addWindowListener( new WindowAdapter() {
            public void windowClosing( WindowEvent event ) {
               dispose();
            }
         }
         ); 
   }
   public void show() {
      super.show();
      appletApp.start();
   }
   public void dispose() {
      appletApp.stop();
      super.dispose();
      appletApp.destroy();
   }
Doc 34, Applets Slide # 31

Applet as Application Continued

   public static void main(String[] args ) {
      Frame application = 
         new SimpleAppletApplication( "Test", 200, 100, new HelloApplet() );
      application.show();
   }
}   
S-dec9 50secs Doc 34, Applets Slide # 32

Better Applet Application The following class allows the applet to interact with its AppletContext. It still needs more work.

import java.awt.*;
import java.applet.*;
import java.awt.event.*;
import java.net.URL;
import java.util.Properties;
import java.util.Enumeration;
public class AppletFrame extends Frame
   implements AppletStub, AppletContext {
   
   // Store applet parameters
   Properties parameters = new Properties();
   Applet appletApp;
   
   public AppletFrame( String windowTitle, int width, int height, 
                                 Applet anApplet ) {
      super( windowTitle );
      setSize( width, height );
      appletApp = anApplet;
      appletApp.init();
      add(  BorderLayout.CENTER, appletApp );
   }
   
   public void show() {
      super.show();
      appletApp.start();
   }
   public void dispose() {
      appletApp.stop();
      super.dispose();
      appletApp.destroy();
   }
Doc 34, Applets Slide # 33

Better Applet Application Continued

   public void setParameters( Properties newParameters ) {
      parameters = newParameters;
   }
   
   // AppletStub methods
   public boolean isActive() {
      return true;
   }
   
   public URL getDocumentBase() {
      return null; //Need better default policy
   }
   
   public URL getCodeBase() {
      return null; //Need better default policy
   }
   
   public String getParameter( String name ) {
      String defaultValue = "";
      return parameters.getProperty( name, defaultValue );
   }
   
   public AppletContext getAppletContext() {
      return this;
   }
   
   public void appletResize( int width, int height ) {
      super.setSize( width, height );
      super.invalidate();
      super.validate();
   }
   
Doc 34, Applets Slide # 34

Better Applet Application Continued

   // AppletContext methods
   public AudioClip getAudioClip(URL audioURL ) {
      return null; //Need better default policy
   }
   public Image getImage(URL imageURL ) {
      // Need better policy to handle applet URL to
      // local image file
      return Toolkit.getDefaultToolkit().getImage( imageURL );
   }
   public Applet getApplet( String name ) {
      return null;
   }
   
   public Enumeration getApplets() {
      return null;
   }
   
   public void showDocument( URL pageURL ) { }
   public void showDocument( URL pageURL, String target ) { }
   public void showStatus( String status ) {}
}
Doc 34, Applets Slide # 35

The Browser Mess & Java Plug-in

Different browsers support different versions of the JDK. The browsers have not been able to keep up with the changes in Java. To "improve" the situation, Sun provides a "plug-in" to add to browsers which allows the browsers to use Sun's JVM. You can download the plug-in at: http://java.sun.com/products/plugin/index.html

However, to use the plug-in the HTML files must use special tags. The tags are browser specific. More information about the tags can be found at: http://java.sun.com/products/plugin/1.2/docs/tags.html. There is a converter to add the new tags for you. The converter can be found at: http://java.sun.com/products/plugin/1.2/features.html


S-dec9 2mins Doc 34, Applets Slide # 36

Java Plug-in for IE on Windows 95, 98 or NT 4.0
Original APPLET tag:

<APPLET code="XYZApp.class" codebase="html/" align="baseline"
   width="200" height="200">
   <PARAM NAME="model" VALUE="models/HyaluronicAcid.xyz">
   No JDK 1.2 support for APPLET!!
</APPLET>

New OBJECT tag:

<OBJECT classid="clsid:8AD9C840-044E-11D1-B3E9-00805F499D93"
     width="200" height="200" align="baseline" 
     codebase="http://java.sun.com/products/plugin/1.2/jinstall-12-win32.cab#Version=1,2,0,0">
     <PARAM NAME="code" VALUE="XYZApp.class">
     <PARAM NAME="codebase" VALUE="html/">
     <PARAM NAME="type" VALUE="application/x-java-applet;version=1.2">
     <PARAM NAME="model" VALUE="models/HyaluronicAcid.xyz">
         No JDK 1.2 support for APPLET!!
 </OBJECT>
S-dec9 19secs Doc 34, Applets Slide # 37

Java Plug-in for Navigator 3 or 4
Original APPLET tag:

<APPLET code="XYZApp.class" codebase="html/" align="baseline"
   width="200" height="200">
   <PARAM NAME="model" VALUE="models/HyaluronicAcid.xyz">
   No JDK 1.2 support for APPLET!!
</APPLET>

New EMBED tag:

 <EMBED type="application/x-java-applet;version=1.2" width="200"
    height="200" align="baseline" code="XYZApp.class"
    codebase="html/" model="models/HyaluronicAcid.xyz"
    pluginspage="http://java.sun.com/products/plugin/1.2/plugin-install.html">
 <NOEMBED>
    No JDK 1.2 support for APPLET!!
 </NOEMBED>
 </EMBED>
S-dec9 1min Doc 34, Applets Slide # 38

Java Plug-in for IE & Navigator 3 & 4 Original APPLET tag:

<APPLET code="XYZApp.class" codebase="html/" align="baseline"
   width="200" height="200">
   <PARAM NAME="model" VALUE="models/HyaluronicAcid.xyz">
   No JDK 1.2 support for APPLET!!
</APPLET>

New tag:

<OBJECT classid="clsid:8AD9C840-044E-11D1-B3E9-00805F499D93"
     width="200" height="200" align="baseline"
     codebase="http://java.sun.com/products/plugin/1.2/jinstall-12-win32.cab#Version=1,2,0,0">
 <PARAM NAME="code" VALUE="XYZApp.class">
 <PARAM NAME="codebase" VALUE="html/">
 <PARAM NAME="type" VALUE="application/x-java-applet;version=1.2">
 <PARAM NAME="model" VALUE="models/HyaluronicAcid.xyz">
 <COMMENT>
     <EMBED type="application/x-java-applet;version=1.2" width="200"
        height="200" align="baseline" code="XYZApp.class" 
        codebase="html/" model="models/HyaluronicAcid.xyz"
        pluginspage="http://java.sun.com/products/plugin/1.2/plugin-install.html">
     <NOEMBED>
     </COMMENT>
            No JDK 1.2 support for APPLET!!
     </NOEMBED></EMBED>
 </OBJECT>

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