Setting
up the Java Application Access - Control Panel
Basics.
We will walk you through the individual
account installation procedure, starting with the Control Panel and going from there.
From the domain's Control Panel, Please click on
the JSP Manager Icon. Once you click on the JSP Manager icon, the JSP Manager page will be
displayed. This screen will allow you to do several tasks:
-Enable Java
-Disable Java (If it has been enabled)
-Add Java Applications
-Remove Java Applications
-Add files/directories (For your JSP files and
compiled programs).
Enabling Java
If Java is not enabled, click on the
enable JSP button. Please allow approximately 15 minutes for the server to install it before you
may begin working on your programs. Once the install is complete, you will see that the JSP Manager
displays Java is Currently Enabled.
Once Java has been enabled, a directory called "webapps"
will be created in the www directory. All Java applications should be installed under the "webapps"
directory. The installation of a given application may be done using a secure shell connection to
the server (SSH) or with the use of the Control Panel's JSP Manager (highly recommended).
In this Getting Started example, we will create
an application called "onjava".
To create this application, go to the JSP
Manager, type "onjava" in the field box and then click on the "Add Java Application Access button".
Now that you have added the Java application directory, the following directory structure will have
been created for you automatically:
Begin loading your files. Your "web.xml"
file should be created when you add the "onjava" Java application. It is located in the
/home/$username/www/webapps/onjava/WEB-INF directory.
Please add the contents in
between the <web-app> tags, to the "web.xml" file as shown below:
web.xml code
<?xml version="1.0"
encoding="ISO-8859-1"?>
<!DOCTYPE web-app
PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
"http://java.sun.com/j2ee/dtds/web-app_2_3.dtd">
<web-app>
<servlet>
<servlet-name>login</servlet-name>
<servlet-class>com.onjava.login</servlet-class>
</servlet>
</web-app>
Next, we will create the html interface for the browser and put it into the /home/$username/www/webapps/onjava/
directory.
login.jsp code
<html>
<head>
<title>OnJava Demo</title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
</head>
<body bgcolor="#66CCFF" onLoad="document.loginForm.username.focus()">
<table width="500" border="0" cellspacing="0" cellpadding="0">
<tr>
<td>
<table width="500" border="0" cellspacing="0" cellpadding="0">
<form name="loginForm" method="post" action="servlet/com.onjava.login">
<tr>
<td width="401"><div align="right">User Name: </div></td>
<td width="399"><input type="text" name="username"></td>
</tr>
<tr>
<td width="401"><div align="right">Password: </div></td>
<td width="399"><input type="password" name="password"></td>
</tr>
<tr>
<td width="401"> </td>
<td width="399"><br><input type="Submit" name="Submit"></td>
</tr>
</form>
</table>
</td>
</tr>
</table>
</body>
</html>
You should be able to access the "login.jsp"
page as shown below with your browser.
http://$domainname/webapps/onjava/login.jsp
You will be prompted for a
username and password (any username and password would do for the purpose of this guide), click the
"Submit" button.
Then a "Welcome" page will display on your browser. To create this Welcome page, make a "welcome.jsp"
file, with the contents shown below. This page is to be put in the same directory as the
login.jsp file, /home/$username/www/webapps/onjava/
If a database of usernames and passwords
existed, the database would be searched and a welcome page would return with the correct person's name.
Welcome.jsp code:
<html>
<head>
<title>OnJava Demo</title>
<meta http-equiv="Content-Type"
content="text/html; charset=iso-8859-1">
</head>
<b>Welcome : <%= request.getAttribute("USER")%>
</html>
Now it is time to Add and compile the script:
com
onjava
Next, please create the following "login.java" file, into the /home/$username/www/webapps/onjava/WEB-INF/classes/com/onjava
directory.
login.java code:
package com.onjava;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
public class login extends HttpServlet
{
private String target = "/welcome.jsp";
private String getUser(String
username, String password) {
// Just return a static name
// If this was reality, we would
perform a SQL lookup
return "Alabanza";
}
public void init(ServletConfig config)
throws ServletException {
super.init(config);
}
public void doGet(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException
{
// If it is a get request forward to
doPost()
doPost(request, response);
}
public void doPost(HttpServletRequest
request,
HttpServletResponse response)
throws ServletException, IOException
{
// Get the username from the request
String username =
request.getParameter("username");
// Get the password from the request
String password =
request.getParameter("password");
String user = getUser(username,
password);
// Add the fake user to the request
request.setAttribute("USER", user);
// Forward the request to the target
named
ServletContext context =
getServletContext();
RequestDispatcher dispatcher =
context.getRequestDispatcher(target);
dispatcher.forward(request,
response);
}
public void destroy() {
}
}
After you load the above login.java file into the directory, you should compile from the same directory
that the file is located, the syntax is as follows:
javac login.java
This will create a compiled file called:
login.class
THAT'S IT!
If you can access the above http://$domainname/webapps/onjava/login.jsp and get the welcome page as a
result, then you were successful in this "Getting Started With JSP" guide.
IMPORTANT NOTES: In order to eliminate
the need to restart "Tomcat" when new Java applications are added, Please add your ".war" file or
servlet application, including any compiling of .java code BEFORE using the Control Panel's "JSP
Manager" interface to actually activate the application.
Please know that you may add stand alone JSP pages at any time without the need to use the "JSP
Manager" interface or restart Tomcat. Under these conditions though, the stand alone JSP page must be
placed in the webapps directory.
Also, Moving a Java servlet from a non-JSP server to a JSP server requires rewriting of the servlets.
Servlets require different configurations once they are moved to a JSP server.
