/*
* This example is from the book "Java Enterprise in a Nutshell".
* Copyright (c) 1999 by O'Reilly & Associates.
* You may distribute this source code for non-commercial purposes only.
* You may study, modify, and use this example for any purpose, as long as
* this notice is retained. Note that this example is provided "as is",
* WITHOUT WARRANTY of any kind either expressed or implied.
*/
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
import java.io.*;
public class AtmServlet extends HttpServlet {
Account act;
public void init(ServletConfig conf) throws ServletException {
super.init(conf);
act = new Account();
act.balance = 0;
}
public void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
resp.setContentType("text/html");
PrintWriter out = resp.getWriter();
out.println("<HTML><BODY>");
out.println("<H2>First Bank of Java ATM</H2>");
out.println("Current Balance: <B>" + act.balance + "</B><BR>");
out.println("<FORM METHOD=POST ACTION=/servlet/AtmServlet>");
out.println("Amount: <INPUT TYPE=TEXT NAME=AMOUNT SIZE=3><BR>");
out.println("<INPUT TYPE=SUBMIT NAME=DEPOSIT VALUE=\"Deposit\">");
out.println("<INPUT TYPE=SUBMIT NAME=WITHDRAW VALUE=\"Withdraw\">");
out.println("</FORM>");
out.println("</BODY></HTML>");
}
public void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
int amt=0;
try {
amt = Integer.parseInt(req.getParameter("AMOUNT"));
}
catch (NullPointerException e) {
// No Amount Parameter passed
}
catch (NumberFormatException e) {
// Amount Parameter was not a number
}
synchronized(act) {
if((req.getParameter("WITHDRAW") != null) && (amt < act.balance))
act.balance = act.balance - amt;
if((req.getParameter("DEPOSIT") != null) && (amt > 0))
act.balance = act.balance + amt;
} // end synchronized block
doGet(req, resp); // Show ATM screen
}
public void destroy() {
// This is where we would save the balance to a file
}
class Account {
public int balance;
}
}
|
