Servlet App Event Listeners
Pages: 1, 2, 3, 4, 5, 6, 7
Listing 5: The code for the servlet
that takes the HTML form information and does the actual manipulation
of the ServletContext
object. (ServletContextAttrib.java)
package com.servlets;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class ServletContextAttrib extends HttpServlet
{
public void service(HttpServletRequest request,
HttpServletResponse response)
throws IOException, ServletException
{
response.setContentType("text/html");
ServletOutputStream out = response.getOutputStream();
out.print("<?xml version='1.0' encoding='UTF-8'?>");
out.print("<!DOCTYPE html");
out.print("PUBLIC '-//W3C//DTD XHTML 1.0 Strict//EN'");
out.print("'DTD/xhtml1-strict.dtd'>");
out.print("<html>");
out.print("<head>");
out.print("<title>ServletContext Attributes</title>");
out.print("</head>");
out.print("<body>");
ServletContext context = getServletContext();
String action = request.getParameter("action");
String name = request.getParameter("name");
String value = request.getParameter("value");
if (action == null) {}
else {
if (action.equals("add"))
{
String test = (String) context.getAttribute(name);
if (test == null)
{
context.setAttribute(name, value);
out.print("Added Item To ServletContext object");
} else {
context.setAttribute(name, value);
out.print("Replaced Item in ServletContext");
}
}
else if (action.equals("remove"))
{
String test = (String) context.getAttribute(name);
if (test == null) {
out.print("Item does not exist");
} else {
context.removeAttribute(name);
out.print("Removed Item From ServletContext");
}
}
else
{
String test = (String) context.getAttribute(name);
if (test == null)
{
context.setAttribute(name, value);
out.print("Added Item To ServletContext object");
} else {
context.setAttribute(name, value);
out.print("Replaced Item in ServletContext");
}
}
}
out.print("<center> <br /> <br />");
out.print("<a href='./servletcontextattrib.html'>");
out.print("Back To Home Page");
out.print("</a>");
out.print("</center>");
out.print("</body>");
out.print("</html>");
}
}
