<%
/*
* add.jsp
*
* Adds a new entry to the address book. This is a JSP that serves 2
* functions. First of all, when called with no arguments, it will display a
* table with a few input fields. The user should enter the name, address and
* city of the new address entry to be added. When he/she submits this
* information, it is sent to this page again. If it is successful, then the
* user can continue adding new entries. If it is not, then the old data will
* be displayed, and a warning message will be shown to the user.
*
* Version: $Revision: 1.1 $ $Date: 2005/02/08 10:10:55 $
* Authors: Ernst de Haan (ernst@jollem.com)
*/
%>
<%@ page import="addressbook.ejb.*,java.io.*,java.util.*,javax.naming.*" %>
<%
// Make sure this page will not be cached by the browser
response.addHeader("Pragma", "no-cache");
response.addHeader("Cache-Control", "no-store");
// We will send error messages to System.err, for verbosity. In a real
// application you will probably not want this.
PrintStream errorStream = System.err;
// If we find any fatal error, we will store it in this variable.
String error = null;
// In a moment we will check if the name, address and city were passed to this
// page. If they were not, then these variables will be set to contain the
// empty string ("").
String name = "";
String address = "";
String city = "";
// This variable indicates what function of this page is currently used. If
// this page is called with parameters, then a new address entry should be
// added. In that case this variable is true.
boolean submitting = false;
// We will first attempt to get the reference to the address book from the
// session. The "list.jsp" page sets this attribute in the session.
AddressBook addressBook = (AddressBook) session.getAttribute("AddressBook");
if (addressBook == null) {
error = "No connection with the AddressBook bean established.";
} else {
// Attempt to get all 3 parameters from the session
name = request.getParameter("name");
address = request.getParameter("address");
city = request.getParameter("city");
// If all 3 parameters are specified, then this is probably a submission by
// this very page. Note that if the user left one of the fields blank, then
// the corresponding parameter will be "", not null.
if (name != null && address != null && city != null) {
name = name.trim();
address = address.trim();
city = city.trim();
submitting = true;
}
}
// In the following variable we will store a (non-fatal) warning message. This
// message will be displayed in the page, but so will the submission form.
String warning = null;
if (submitting) {
warning = "";
// If there is an empty name, address and/or city, then this will be noted
// in the warning message.
if ("".equals(name)) {
warning = "No name specified. ";
}
if ("".equals(address)) {
warning += "No address specified. ";
}
if ("".equals(city)) {
warning += "No city specified.";
}
// If we don't have a warning message yet, then we will attempt to create
// the new address entry.
if ("".equals(warning)) {
try {
addressBook.create(name, address, city);
// We will only get here if the previous statement succeeded. If it
// did succeed, then the fields on the page should be empty, and the
// warning message will be set to null, for easy comparison checking
// later on.
name = "";
address = "";
city = "";
// If we got this far, then there was no problem detected.
warning = null;
} catch (Exception e) {
// Set the warning variable to indicate a problem.
warning = "Unable to create new entry, caught: \"" +
e.getClass().getName() + "\", message is: \"" +
e.getMessage() + "\".";
}
}
}
// Decide what the title will be.
String title;
if (error != null) {
title = "Error";
} else {
title = "Addressbook | Add entry";
}
%>
<%= title %>
<%= title %>
<%
// If there was a fatal error, then display the error message
if (error != null) {
%>
<%= error %>
<%
// Otherwise display a table with fields to be filled in.
} else {
// If there was a warning, then display it.
if (warning != null) {
%>
<%
} /* if */
// Display the table with fields. There are two columns. The left column
// contains the names of the fields, while the right column contains the
// fields.
%>
<%
} /* else */
%>