import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class ChatDispatch extends HttpServlet {
public void doGet(HttpServletRequest req, HttpServletResponse res)
throws IOException, ServletException {
res.setContentType("text/html");
if (!req.getParameterNames().hasMoreElements()) {
// There were no request parameters. Print a welcome page.
printWelcomePage(req, res);
}
else {
// There was at least one request parameter.
// Print a page containing the applet.
printAppletPage(req, res);
}
}
// The welcome page greets the reader and has a form where the user
// can choose an applet-servlet communication method.
private void printWelcomePage(HttpServletRequest req,
HttpServletResponse res)
throws IOException {
PrintWriter out = res.getWriter();
String me = req.getServletPath();
out.println("");
out.println("");
out.println("Welcome to an Absurdly Simple Chat");
out.println("");
out.println();
out.println("");
out.println("Welcome to an Absurdly Simple Chat
");
out.println();
out.println("Would you like to communicate via:");
out.println("");
out.println(" - http");
out.println("
- socket");
out.println("
- rmi");
out.println("
");
out.println("");
}
// The applet page displays the chat applet.
private void printAppletPage(HttpServletRequest req,
HttpServletResponse res)
throws IOException {
PrintWriter out = res.getWriter();
out.println("");
out.println("An Absurdly Simple Chat");
out.println("");
out.println("An Absurdly Simple Chat
");
String method = req.getParameter("method");
String user = req.getRemoteUser();
String applet = null;
if ("http".equals(method)) {
applet = "HttpChatApplet";
}
else if ("socket".equals(method)) {
applet = "SocketChatApplet";
}
else if ("rmi".equals(method)) {
applet = "RMIChatApplet";
}
else {
// No method given, or an invalid method given.
// Explain to the user what we expect.
out.println("Sorry, this servlet requires a method " +
"parameter with one of these values: " +
"http, socket, rmi");
return;
}
// Print the HTML code to generate the applet.
// Choose the applet code based on the method parameter.
// Provide a user parameter if we know the remote user.
out.println("");
out.println("");
}
}