package com.oreilly.jent.servlets;
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*
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* includes the title, author, publisher, and ISBN. For example:
*
* "Java Enterprise in a Nutshell, Third Edition,
* by Jim Farley and William Crawford
* with Prakash Malani, John G. Norman, and Justin Gehtland.
* Copyright 2006 O'Reilly Media, Inc., 0-596-10142-2."
*
* If you feel your use of code examples falls outside fair use or the
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import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
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>");
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;
}
}
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