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Message:

password

Posted by zenek on October 24, 2001 at 10:03 AM

>

This is just for your info. If you are interested in knowing how two applets in a browser interacts then please keep reading

> STEP1: Create two applets and let us call then
> InterApplet1 and InterApplet2. I will explain the
> code for these applets later .
> STEP2: Create two HTML files and place the two applets created
> in STEP1 in them . Let us call the two HTML files as
> InterApplet1.html and InterApplet2.HTML. Let us name
> the applet tag in InterApplet1.html as app1 and that of in
> InterApplet2.html as app2.
>
> STEP3: Create another HTML file and put two frames in it. Let us name
> these two frames as f1 and f2. The source file for f1 frame is
> InterApplet1.html and for f2 it is InterApplet2.html. Let us call this
> HTML file as InterApplet.html.

> STEP4: Utill now we have just created a html document with two
> frames in it named as f1 and f2 and placed the two applets
> in them named app1 and app2 respectively.

> STEP5: Create a class in java called Args. You can name it anything you
> want. I just called it Agrs. This Args class has an instance
> variable of String type which will hold a text. User
> will type in a text in applet1 displayed in frame1 and click
> a button. On button click I will read the text typed by user
> then create an object of Args class and set the instance variable
> equal to the text typed by the user. Then I wll get the
> reference of the applet 2 displayed in frame 2 and call
> passArg method in applet 2 ( In fact, InterApplet2.class ).
> The passArg method of applet 2 takes one argument of type Args.
> It reads the instance variable's text in Args object and then
> displays the text in text area in frame 2.
> STEP6: Let us discuss how do we get the reference of second applet
> which is in frame 2 inside applet1 which is in frame1
> You need to use JSObject class to accomplish this. You can find
> this class netscape.javascript.JSObject somewhere in windows directory
> of your windows95/98 or with a .jar file in JRE installed directory
> for your JDK.
> We call getWindow () method of the JSObject to get the reference
> of the window in which the applet resides
> JSObject win = win.getWindow ( this ) ;
> You need to pass the reference of the applet from which you are
> calling this getWindow ( ) method. Here "this" is the reference of the
> applet.
> Now "win" has the reference of the window representing frame1 in our case.
> Note that we are calling this method from applet1 in Frame 1. Now using
> getMember () method you can get any property of this window "win" . We want to
> get the reference of the top level window of the browser.
>
> JSObject topWin = ( JSObject ) win.getMember ( "parent" ) ;
>
> Note that getMember () method returns an Object so we need to cast it. Note the
> also the user of "parent" property for Frame1 . Now we can get the reference of Frame2
> as
> JSObject frame2 = ( JSObject ) topWin.getMember ( "f2" ) ;
>
> Once you have reference of frame 2 then you can get the refernce of applet 2 as
> JSObject applet2 = ( JSObject ) frame2.getMember ( "app2" ) ;
>
> Following code create an object to pass to applet 2
> Args args = new Args ( ) ;
> // Set the parameter in the argument object
> args.setMsg ( t1.getText ( ) ) ;
>
> // call method accepts array of Object as an argument
> Object[] argsArray = { args } ;
>
> // Call the passMsg method in applet 2
> applet2.call( "passMsg", argsArray ) ;
>
> Yuo use the call () method of JSObject to call a method passing method name and arguments
> as its parameter.

> /*****************************************/
> If your two applets are in same frame then you can get the
> reference of aplet 2 as follows.
> JSObject win = JSObject.getWindow ( this ) ;
> JSObject doc = ( JSObject ) win.getMember ( "document" ) ;
> JSObject temp = ( JSObject ) doc.getMember ( "app2" ) ;
> /****************************************/

> /******************************* All the files used in this demo follows **************/

> /////////////////// InterApplet1.java ////////////////////////////
> import java.applet.Applet ;
> import java.awt.* ;
> import java.awt.event.* ;

> import netscape.javascript.JSObject ;

> public class InterApplet1 extends Applet implements ActionListener{
> Button b1 = new Button ( "Click Me" ) ;
> TextArea t1 = new TextArea ( 10, 40 ) ;
>
> public void init ( ) {
>
> // Add the a button and a text field to the applet
> add ( b1 ) ;
> add ( t1 ) ;
>
> // Add action listener to the button. On button clicked
> // actionPerformed event will be triggered and we will
> // call a method in an applet which is in another frame
> b1.addActionListener ( this ) ;
> }
>
> public String getMsg ( ) {
> return "Hello, from applet 1" ;
> }
>
> public void actionPerformed ( ActionEvent e ) {
> try {
>
> // Create a reference of the current window in win object
> JSObject win = JSObject.getWindow ( this ) ;
>
> // Get the reference of the parent window. It gives you the top level window
> JSObject topWin = ( JSObject ) win.getMember ( "parent" ) ;
>
> //Get the refernce of second frame in window. We named the second frame
> // as f2
> JSObject frame2 = ( JSObject ) topWin.getMember ( "f2" ) ;
>
> // Get the reference of the applet in frmae f2. It is named app2
> JSObject applet2 = ( JSObject ) frame2.getMember ( "app2" ) ;
>
>
> // Create the argument object to be passed to applet 2 which is in frame 2
> Args args = new Args ( ) ;
>
> // Set the parameter in the argument object
> args.setMsg ( t1.getText ( ) ) ;
>
> // call method accepts array of Object as an argument
> Object[] argsArray = { args } ;
> // Call the passMsg method in applet 2
> applet2.call( "passMsg", argsArray ) ;
>
> } catch ( Exception e1 ) {
> //Handle your execptions
> t1.setText ( "Exception:" + e1.getMessage ( ) ) ;
> }
> }
> }

>
> //////////////////// End of InterApplet1.java///////////////////

>
> /////////////////// InterApplet2.java ////////////////////////////

> import java.applet.Applet ;
> import java.awt.* ;
> import java.awt.event.* ;

> import netscape.javascript.JSObject ;

> public class InterApplet2 extends Applet {
> TextArea t1 = new TextArea ( 10, 40 ) ;
> public void init ( ) {
> add ( t1 ) ;
> }
>
>
> // Read the args message and displays in the text field
> public void passMsg ( Args args ) {
> t1.setText ( args.getMsg ( ) ) ;
> }
> }

> //////////////////// End of InterApplet2.java///////////////////

> /////////////////// Args.java ////////////////////////////

> public class Args {
> private String msg = "Hello" ;
>
> public String getMsg ( ) {
> return msg ;
> }
>
> public void setMsg ( String str ) {
> msg = str ;
> }
> }
> //////////////////// End of Args.java///////////////////

> /////////////////// Inte