Programming for beginners: Example Of Cookie

main.jsp

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
   
     <title>Filter Example</title>
    </head>
    <body>
        <form method="post" action="/servlet/Login">
            Enter user Name<input type="text" name="userName" /><br />
            Enter Password<input type="password" name="password" />
            <input type="submit" value ="login">
        </form>
    </body>
</html>

login.java

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.Cookie;

@WebServlet(urlPatterns = {"/Login"})
public class Login extends HttpServlet {
    @Override
    public void doPost(HttpServletRequest req, HttpServletResponse res)throws ServletException, IOException{
        String userName = req.getParameter("userName");
        String password = req.getParameter("password");
        
        if(userName.equals("krishna") && password.equals("krishna")){
            Cookie name = new Cookie("userName", userName);
            res.addCookie(name);
            res.sendRedirect("http://localhost:8080/servlet/Welcome");
        }
        else{
            Cookie name = new Cookie("userName", "username/password is not valid");
            res.addCookie(name);
            res.sendRedirect("http://localhost:8080/servlet/Error");
        }

    }   
}

Welcome.java

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.Cookie;

@WebServlet(urlPatterns = {"/Welcome"})
public class Welcome extends HttpServlet {
  @Override
  public void doPost(HttpServletRequest req, HttpServletResponse res)throws IOException, ServletException{
      try(PrintWriter out = res.getWriter()){
         Cookie[] cookie = req.getCookies();
         
         for(Cookie c : cookie){
             String name = c.getName();
             if(name.equals("userName"))
             out.println("Welcome " + c.getValue());
         }
      }
  }
  
  public void doGet(HttpServletRequest req, HttpServletResponse res)throws IOException, ServletException{
      doPost(req, res);
  }
}

Error.java

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet(urlPatterns = {"/Error"})
public class Error extends HttpServlet {
  @Override
  public void doPost(HttpServletRequest req, HttpServletResponse res)throws IOException, ServletException{
      try(PrintWriter out = res.getWriter()){
         Cookie[] cookie = req.getCookies();
         
         for(Cookie c : cookie){
             String name = c.getName();
             if(name.equals("userName"))
             out.println(c.getValue());
         }
      }
  }
  
  public void doGet(HttpServletRequest req, HttpServletResponse res)throws IOException, ServletException{
      doPost(req, res);
  }
}

Program redirect to the welcome page, if the user name and password is 'krishna', else redirect to error page.

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Programming for beginners

Tuesday, 2 September 2014

Example Of Cookie

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