help for making web pages using servlets

Tue Jan 20, 2009 6:23 pm

how to make web pages using servlets and html pages. how to do session tracking, work with cookies, and invoke another pages in it?

can u give me any simple example of codding to understand these things?

Tue Jan 20, 2009 10:12 pm

1. Example on session tracking , is the tracking of use login overall your site , the session is tracked using the HttpSession class , session is used to save data at the server side for a limited time period .

Code:: import java.io.PrintWriter; import java.io.IOException; import java.util.Date; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; public class SessionTracker extends HttpServlet { public void doGet(HttpServletRequest req, HttpServletResponse res)throws ServletException, IOException { res.setContentType("text/html"); PrintWriter out = res.getWriter(); HttpSession session = req.getSession(true); String user = (String) session.getAttribute("username"); String content=" " ; if (user == null) { content="<a herf='http://www.mysite/login/'>Login</a>"; } else { content="Welcome "+user+" , <a herf='http://www.mysite/logout/'>Logout</a> "; } out.println("<html><head><title>Site main page</title></head>"); out.println("<body><h1>Login/Logout session tracking </h1>"); out.println(content);// Show a link for login or logout out.println("</body></html>"); } }

There is functions with the session object that may help you alot ,
- To get session ID

Code:: session.getId();

- Get the max time of session to be expired

Code:: session.getMaxInactiveInterval();

- Get the session created Time

Code:: session.getCreationTime();

2 .Cookies are the instances that are saved at the client side browser to keep information to be used for the next visits .In servlets , the cookies are sent using the request object .We will check if an cookie is already created otherwise we will create one . Here for example i will save the username in a cookie .

Code:: import java.io.*; import javax.servlet.*; import javax.servlet.http.*; public class SettingandReadingCookies extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException { response.setContentType("text/html"); PrintWriter out = response.getWriter(); out.println("<HTML><HEAD><TITLE>WEB_PAGE</TITLE></HEAD><BODY>"); Cookie[] cookies = request.getCookies(); boolean Cookiethere = false; for(int i = 0; i < cookies.length; i++) { Cookie currentCookie = cookies[i]; if (currentCookie.getName().equals("username")) { out.println("username = " + currentCookie.getValue()); Cookiethere = true; } } if (!Cookiethere) { Cookie newcookie = new Cookie("username", "msi_333"); response.addCookie(newcookie); // Add Cookie at client } out.println("This page show your username when reloaded."); out.println("</BODY>"); out.println("</HTML>"); } }

help for making web pages using servlets

help for making web pages using servlets

Re: help for making web pages using servlets