Applet servlet communication

[priya shankar]

Hi all
Have a look at the following progrm
My Applet

import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.net.*;
/*<applet code="EchoApplet.class" width="500" height="200"></applet>*/
/**
 * Simple demonstration for an Applet <-> Servlet communication.
 */
public class EchoApplet extends Applet {
private TextField inputField = new TextField();
private TextField outputField = new TextField();
private TextArea exceptionArea = new TextArea();
/**
 * Setup the GUI.
 */
public void init() {
// set new layout
setLayout(new GridBagLayout());
// add title
Label title = new Label("Echo Applet", Label.CENTER);
title.setFont(new Font("SansSerif", Font.BOLD, 14));
GridBagConstraints c = new GridBagConstraints();
c.gridwidth = GridBagConstraints.REMAINDER;
c.weightx = 1.0;
c.fill = GridBagConstraints.HORIZONTAL;
c.insets = new Insets(5, 5, 5, 5);
add(title, c);
// add input label, field and send button
c = new GridBagConstraints();
c.anchor = GridBagConstraints.EAST;
add(new Label("Input:", Label.RIGHT), c);
c = new GridBagConstraints();
c.fill = GridBagConstraints.HORIZONTAL;
c.weightx = 1.0;
add(inputField, c);
Button sendButton = new Button("Send");
c = new GridBagConstraints();
c.gridwidth = GridBagConstraints.REMAINDER;
add(sendButton, c);
sendButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
System.out.println("connection");
onSendData();
}
});
// add output label and non-editable field
c = new GridBagConstraints();
c.anchor = GridBagConstraints.EAST;
add(new Label("Output:", Label.RIGHT), c);
c = new GridBagConstraints();
c.gridwidth = GridBagConstraints.REMAINDER;
c.fill = GridBagConstraints.HORIZONTAL;
c.weightx = 1.0;
add(outputField, c);
outputField.setEditable(false);
// add exception label and non-editable textarea
c = new GridBagConstraints();
c.anchor = GridBagConstraints.EAST;
add(new Label("Exception:", Label.RIGHT), c);
c = new GridBagConstraints();
c.gridwidth = GridBagConstraints.REMAINDER;
c.weighty = 1;
c.fill = GridBagConstraints.BOTH;
add(exceptionArea, c);
exceptionArea.setEditable(false);
}
/**
 * Get a connection to the servlet.
 */
private URLConnection getServletConnection()
throws MalformedURLException, IOException {
//System.out.println(getCodeBase());
// Connection zum Servlet �ffnen
URL urlServlet = new URL(getCodeBase(),"echo/EchoServlet");
System.out.println("url"+urlServlet);
URLConnection con = urlServlet.openConnection();
System.out.println("con"+con);
// konfigurieren
con.setDoInput(true);
con.setDoOutput(true);
con.setUseCaches(false);
con.setRequestProperty(
"Content-Type",
"application/x-java-serialized-object");

// und zur�ckliefern
return con;
}
/**
 * Send the inputField data to the servlet and show the result in the outputField.
 */
private void onSendData() {
try {
// get input data for sending
String input = inputField.getText();
System.out.println("connection");
// send data to the servlet
URLConnection con = getServletConnection();
System.out.println("con"+con);
OutputStream outstream = con.getOutputStream();
System.out.println("connn"+con);
ObjectOutputStream oos = new ObjectOutputStream(outstream);
oos.writeObject(input);
oos.flush();
oos.close();
// receive result from servlet
InputStream instr = con.getInputStream();
ObjectInputStream inputFromServlet = new ObjectInputStream(instr);
String result = (String) inputFromServlet.readObject();
System.out.println("result "+result );
inputFromServlet.close();
instr.close();
// show result
outputField.setText(result);
} catch (Exception ex) {
ex.printStackTrace();
exceptionArea.setText(ex.toString());
}
}
}
My  Servlet
import java.io.*;
import javax.servlet.ServletException;
import javax.servlet.http.*;
/**
 * Simple demonstration for an Applet <-> Servlet communication.
 */
public class EchoServlet extends HttpServlet {
/**
 * Get a String-object from the applet and send it back.
 */
public void doPost(
HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
try {
response.setContentType("application/x-java-serialized-object");
// read a String-object from applet
// instead of a String-object, you can transmit any object, which
// is known to the servlet and to the applet
InputStream in = request.getInputStream();
ObjectInputStream inputFromApplet = new ObjectInputStream(in);
String echo = (String) inputFromApplet.readObject();
// echo it to the applet
OutputStream outstr = response.getOutputStream();
ObjectOutputStream oos = new ObjectOutputStream(outstr);
oos.writeObject(echo);
oos.flush();
oos.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}

When i call the servlet through a Browser i get the following Exception...

"Protocal Doesn't support the output"
When i called the servlet throug consloe(by running applet)
I get
File not found exception

Please let me know what is the problem
thankx
priya
[ June 17, 2003: Message edited by: Cindy Glass ]

[Torsten Schippel]

Hi priya,
sorry but your code is working fine. I only get the exception if I run it inside the IDE. in this case the getCodeBase returns an incorrect protocol (file://). Set the URL to a complete address like http://localhost/EchoServlet. Then it works inside the IDE or locally.
HTH
Torsten