import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
/* This class acts as a simple reservation system (which doesn't
actually reserve anything) in order to demo how form data can be
processed and a response page can be generated.
*/
// We extend the HttpServlet class, which contains all of the methods
// necessary to respond to either POST or GET methods of sending
// form data.
public class ReservationServlet extends HttpServlet {
// Since our web page form that will submit the data does so using
// the POST method, we implement doPost (we would implement doGet
// if the GET method were used). This is passed objects containing
// request data sent from the form, and response data which will be
// sent back to the browser. Note that it should always throw a
// ServletException as well (this is a non-runtime exception).
public void doPost(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
// The response object is like a file in the sense that we can
// create a PrintWriter object to send String data into the
// object (this string will be the web page that will be sent
// back to the browser). Once we have created a PrintWriter that
// is connected to the response, we can use println to send the
// data into it.
PrintWriter out = response.getWriter();
// The request object contains data about the requester other than
// just the form data. Commonly used data includes the hostname
// and host address of the requestor, among others.
String remoteHost = request.getRemoteHost();
String remoteAddr = request.getRemoteAddr();
// Each piece of form data sent is in "name=value" form, where the
// name is that given in the HTML of the form, and the value is
// whatever the user entered. Each of these can be retrieved using
// the getParameter method.
// For text elements, the value is whatever the user typed into the box
String name = request.getParameter("name");
String course = request.getParameter("course");
String password = request.getParameter("password");
// For checkboxes, the value is either "on" if the checkbox was checked,
// or null if it was not checked. CHecking for null is the simplest
// way to get the value.
String office = request.getParameter("Office");
String studio = request.getParameter("Studio");
String java = request.getParameter("Java");
String adobe = request.getParameter("Adobe");
// For radio buttons and single option lists, the value is
// that attached to the button selected,
// or null if none are selected (you should check for this!)
String room = request.getParameter("room");
if (room == null) {
out.println("Request could not be processed -- room missing!");
return;
}
String time = request.getParameter("time");
String why = request.getParameter("why");
// If a multiple-option list is used, the request object contains
// an array of values corresponding to all options selected, or
// null if none were selected.
String dayString = "";
String[] days = request.getParameterValues("days");
if (days == null) {
out.println("Request could not be processed -- days missing!");
return;
}
int dayLength = days.length;
if (dayLength == 1) dayString = days[0];
else if (dayLength == 2) dayString = days[0] + " and " + days[1];
else {
for (int i = 0; i < dayLength - 1; i++)
dayString = dayString + days[i] + ", ";
dayString = dayString + " and " + days[dayLength - 1];
}
// To send a response page to the browser, we write strings corresponing
// to a page in HTML to the response object.
out.println("Response to reservation");
out.println("Thank you, " + name);
out.println(" on " + remoteHost + " at " + remoteAddr + "
");
out.println("This is to acknowledge that you have reserved room " + room);
out.println(" at " + time + " on " + dayString + "
");
out.println("The following software will be available: ");
if (office != null) out.println("
Microsoft Office");
if (studio != null) out.println("
Visual Studio");
if (java != null) out.println("
Java SDK");
if (adobe != null) out.println("
Adobe Acrobat");
out.println("
");
out.println("Other comments: " + why + "
");
out.println("");
}
}