login example

1.Loginpage.jsp

<%@ page language="java" contentType="text/html; charset=windows-1256"
    pageEncoding="windows-1256"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">

<html>
<head>
<meta http-equiv="Content-Type"
    content="text/html; charset=windows-1256">
<title>Login Page</title>
</head>

<body>
<form action="LoginServlet">Please enter your username <input
    type="text" name="un" /><br>

Please enter your password <input type="text" name="pw" /> <input
    type="submit" value="submit"></form>
</body>
</html>


2.invalidLogin.jsp

<%@ page language="java" 
      contentType="text/html; charset=windows-1256"
      pageEncoding="windows-1256"
   %>

   <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"    
      "http://www.w3.org/TR/html4/loose.dtd">

   <html>

      <head>
         <meta http-equiv="Content-Type" 
            content="text/html; charset=windows-1256">
         <title>Invalid Login</title>
      </head>

      <body>
         <center>
            Sorry, you are not a registered user! Please sign up first
         </center>
      </body>

   </html>

3.userlogged.jsp


<%@ page language="java" 
         contentType="text/html; charset=windows-1256"
         pageEncoding="windows-1256"
         import="ExamplePackage.UserBean"
   %>

   <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" 
   "http://www.w3.org/TR/html4/loose.dtd">

   <html>

      <head>
         <meta http-equiv="Content-Type" 
            content="text/html; charset=windows-1256">
         <title>   User Logged Successfully   </title>
      </head>

      <body>

         <center>
            <% UserBean currentUser = (UserBean) (session.getAttribute("currentSessionUser"));%>

            Welcome <%= currentUser.getFirstName() + " " + currentUser.getLastName() %>
         </center>

      </body>

   </html>

4.LoginServlet.java

package ExamplePackage;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
 * Servlet implementation class LoginServlet
 */
public class LoginServlet extends HttpServlet {


public void doGet(HttpServletRequest request, HttpServletResponse response) 
                       throws ServletException, java.io.IOException {

try
{       

     UserBean user = new UserBean();
     user.setUserName(request.getParameter("un"));
     user.setPassword(request.getParameter("pw"));

     user = UserDAO.login(user);

     if (user.isValid())
     {

          HttpSession session = request.getSession(true);       
          session.setAttribute("currentSessionUser",user); 
          response.sendRedirect("userLogged.jsp"); //logged-in page             
     }

     else 
          response.sendRedirect("invalidLogin.jsp"); //error page 
} 


catch (Throwable theException)      
{
     System.out.println(theException); 
}
       }
    }



5.userbean.java

package ExamplePackage;

public class UserBean {

      private String username;
      private String password;
      private String firstName;
      private String lastName;
      public boolean valid;


      public String getFirstName() {
         return firstName;
    }

      public void setFirstName(String newFirstName) {
         firstName = newFirstName;
    }


      public String getLastName() {
         return lastName;
            }

      public void setLastName(String newLastName) {
         lastName = newLastName;
            }


      public String getPassword() {
         return password;
    }

      public void setPassword(String newPassword) {
         password = newPassword;
    }


      public String getUsername() {
         return username;
            }

      public void setUserName(String newUsername) {
         username = newUsername;
            }


      public boolean isValid() {
         return valid;
    }

      public void setValid(boolean newValid) {
         valid = newValid;
    }   
}


6.userdao.java

package ExamplePackage;

import java.text.*;
   import java.util.*;
   import java.sql.*;

   public class UserDAO     
   {
      static Connection currentCon = null;
      static ResultSet rs = null;  



      public static UserBean login(UserBean bean) {

         //preparing some objects for connection 
         Statement stmt = null;    

         String username = bean.getUsername();    
         String password = bean.getPassword();   

         String searchQuery =
               "select * from users where username='"
                        + username
                        + "' AND password='"
                        + password
                        + "'";

      // "System.out.println" prints in the console; Normally used to trace the process
      System.out.println("Your user name is " + username);          
      System.out.println("Your password is " + password);
      System.out.println("Query: "+searchQuery);

      try 
      {
         //connect to DB 
         currentCon = ConnectionManager.getConnection();
         stmt=currentCon.createStatement();
         rs = stmt.executeQuery(searchQuery);           
         boolean more = rs.next();

         // if user does not exist set the isValid variable to false
         if (!more) 
         {
            System.out.println("Sorry, you are not a registered user! Please sign up first");
            bean.setValid(false);
         } 

         //if user exists set the isValid variable to true
         else if (more) 
         {
            String firstName = rs.getString("firstname");
            String lastName = rs.getString("lastname");

            System.out.println("Welcome " + firstName);
            bean.setFirstName(firstName);
            bean.setLastName(lastName);
            bean.setValid(true);
         }
      } 

      catch (Exception ex) 
      {
         System.out.println("Log In failed: An Exception has occurred! " + ex);
      } 

      //some exception handling
      finally 
      {
         if (rs != null)    {
            try {
               rs.close();
            } catch (Exception e) {}
               rs = null;
            }

         if (stmt != null) {
            try {
               stmt.close();
            } catch (Exception e) {}
               stmt = null;
            }

         if (currentCon != null) {
            try {
               currentCon.close();
            } catch (Exception e) {
            }

            currentCon = null;
         }
      }

return bean;

      } 
   }


7.connectionmanager.java


package ExamplePackage;

import java.sql.*;
   import java.util.*;


   public class ConnectionManager {

      static Connection con;
      static String url;

      public static Connection getConnection()
      {

         try
         {

            Class.forName("oracle.jdbc.driver.OracleDriver");
            System.out.println(" Defing the URL");

             String url= "jdbc:oracle:thin:@172.24.137.30:1521:ORA10G";
            // assuming "DataSource" is your DataSource name

           // Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");

            try
            {   


                System.out.println(" Defing the username");
                String username= "e469573"; 
                System.out.println(" Defing the password");
                String password= "nkDquOhwj";
                System.out.println(" Defing the connection");
                con = DriverManager.getConnection(url,username,password); 
                System.out.println(" connection done" +con);





            }

            catch (SQLException ex)
            {
               ex.printStackTrace();
            }
         }

         catch(ClassNotFoundException e)
         {
            System.out.println(e);
         }

      return con;
}
   }
View Answers
January 18, 2012 at 11:57 AM
Specify the error.