<%-- Instantiate the form validation bean and supply the error message map --%>
<%@ page import="com.mycompany.*" %>
<jsp:useBean id="form" class="com.mycompany.MyForm" scope="request">
<jsp:setProperty name="form" property="errorMessages" value='<%= errorMap %>'/>
</jsp:useBean>
<%
// Ask the browser not to cache the page
response.setHeader("Pragma", "no-cache");
response.setHeader("Cache-Control", "no-cache");
// If process is true and a timestamp is present, attempt to validate and process the form
String timestamp = request.getParameter("timestamp");
if ("true".equals(request.getParameter("process")) && timestamp != null) {
// Check timestamp
if (!timestamp.equals(session.getAttribute("com.mycompany.MyForm.timestamp"))) {
response.sendRedirect("formAlreadyDone.jsp");
return;
}
%>
<jsp:setProperty name="form" property="*" />
<%
if (form.process()) {
// Save a new timestamp in the session
timestamp = ""+System.currentTimeMillis();
session.setAttribute("com.mycompany.MyForm.timestamp", timestamp);
// Go to success page
response.sendRedirect("formDone.jsp");
return;
}
} else {
timestamp = ""+System.currentTimeMillis();
session.setAttribute("com.mycompany.MyForm.timestamp", timestamp);
}
%>
<html>
<head><title>A Simple Form That Prevents Duplicate Submissions</title></head>
<body>
<%-- When submitting the form, resubmit to this page --%>
<form action='<%= request.getRequestURI() %>' method="POST">
<%-- email --%>
<font color=red><%= form.getErrorMessage("email") %></font><br>
Email: <input type="TEXT" name="email" value='<%= form.getEmail() %>'>
<br>
<%-- zipcode --%>
<font color=red><%= form.getErrorMessage("zipcode") %></font><br>
Zipcode: <input type="TEXT" name="zipcode" value='<%= form.getZipcode() %>'>
<br>
<input type="SUBMIT" value="OK">
<input type="HIDDEN" name="process" value="true">
<%-- Save the timestamp in the form --%>
<input type="HIDDEN" name="timestamp" value="<%= timestamp %>">
</form>
</body>
</html>
<%!
// Define error messages
java.util.Map errorMap = new java.util.HashMap();
public void jspInit() {
errorMap.put(MyForm.ERR_EMAIL_ENTER, "Please enter an email address");
errorMap.put(MyForm.ERR_EMAIL_INVALID, "The email address is not valid");
errorMap.put(MyForm.ERR_ZIPCODE_ENTER, "Please enter a zipcode");
errorMap.put(MyForm.ERR_ZIPCODE_INVALID, "The zipcode must be 5 digits");
errorMap.put(MyForm.ERR_ZIPCODE_NUM_ONLY, "The zipcode must contain only digits");
}
%>
