Applet Communication

Hehe good news, for I think I know EXACTLY the solution you are looking for! :-) Having this problem myself in the past, I devised a method for passing variables to a server through the use of GET requests and server-side scripts.

What I recommend for your needs in exactly the same technique. Please review the following two scripts (the first in Java, the second in Perl [ www.perl.com ]) and extract any code snippets that you may need. Enjoy!

Regards,

Brad Galiette

(While on the subject, if you also have the requirement for your server-side script to return information to the applet, please contact me for a slight addition to both scripts.)

<PRE>

import java.net.*;

import java.awt.*;

class JavaFile1 extends java.applet.Applet{

Label status = new Label("Complete the Form");

TextField textValue = new TextField();

FlowLayout dLayout = new FlowLayout();

Choice choiceList = new Choice();

Button submitData = new Button("Submit");

URL transUrl;

URLEncoder ue = new URLEncoder();

URLConnection servConnect;

public void init(){

//Retrieve list items as parameters on the host HTML form. Parameters,

//in this scnario, should be in the form of:

//

// <APPLET ... >

//<PARAM NAME = "listOptions0" VALUE = "Whose On First">

//<PARAM NAME = "listOptions1" VALUE = "Whats On Second">

//<PARAM NAME = "listOptions2" VALUE = "I Don't Know's On Third">

//...

// </APPLET>

//

//(Note - There is no limit to the number of elements that can exist

//in the Choice list provided that the first parameter is

//"listOptions0", and ever subsequent parameter follows at increments

//of one. Furthermore, the items shall appear in the order

//that there "NAME" value specifies (e.g., "listOptions0" first,

//followed by "listOptions1", etc.)

//

int loInc = 0;

while (getParameter("listOptions" + loInc) != null){

choiceList.addItem(getParameter("listOptions" + loInc));

loInc++;

}

//Display the components in a flow layout

setLayout(dLayout);

add(textValue);

add(choiceList);

add(submitData);

}

//Send the data to the host via a GET request and/or

void submitData(){

//Encode the URL in the "transUrl" URL object

try{

transUrl = new URL(ue.encode("http://myserver/cgi-bin/my_form.cgi?text_field=" + textValue.getText() + "&choice_value=" + choiceList.getSelectedItem()));

} catch(MalformedURLException e){}

//Be aware that there are two ways to go about submitting data to

//a server-based script. In the first, only the data is sent

//via an internal GET request (note that this does NOT transfer

//the user to a different web page); in the second, the information

//is submitted via an external GET request thus causing the page

//to change entirely. Depending upon your needs, it is important

//to know both techniques.

//Example 1

status.setText("Sending Information...");

try{

servConnect = this.serverlet.openConnection();

servConnect.connect();

} catch(IOException e){}

status.setText("Information Sent!");

//Example 2 (This has been commented out to permit for code accuracy;

//if you are in need of changing the page in which your user is

//located, uncomment this code and comment-out the code in "Example 1"

//

// getAppletContext().showDocument(transUrl);

}

//Handle the action of the "Submit Data" button in such a way so that

//submitData() is called.

public boolean action(Event evt, Object arg){

if (evt.target instanceof Button){

String lbl = (String)arg;

if (lbl.equals("Submit")){

submitData();

}

}

}

}

#!/usr/bin/perl

#A library for retrieving GET and POST variables (download at http://cgi-lib.berkeley.edu/ )

require "cgi-lib.pl";

#Retrieve the actual variables; all incoming variables can be accessed via $in{"name_of_variable"}

&ReadParse();

#Print the variables to a file (in practice, you can do anything you desire with the variables received but

#very often, they shall be printed to a file or passed to a database). (Note - The file is being opened in "append"

#mode so that all new additions shall be added to the end of the file. Also, observe that the variables are

#being separated by a "|"; this is a sufficient data separator, but when used for real-world applications,

#make SURE that you filter data to eliminate the "|" [Tip - substitute all instances of "|" with "¦", as

#the latter is the HTML-code equivalent of "|"; a simple command for doing this is $myvar=~s/\|/¦/ig;

#assuming, of course, that $myvar is the variable of your data.])

open(DBFILE, ">>dbfile.txt");

print DBFILE $in{"text_field"} . "|" . $in{"choice_value"} . "\n";

close(DBFILE);

</PRE>

BGaliette at 2007-6-29 18:03:21 >