Question

Login Servlet with session tracking

Asked by: l_starter_l

Hi,
Can someone provide me with an example of a servlet with session tracking that obtains the username and password from a database

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Asked On: 2009-10-19 at 18:50:27ID24825605
Tags: servlet
,; java
,; database
Topics: Java Servlets
,; New to Java Programming
,; Java Programming Language
Participating Experts: 1
Points: 500
Comments: 14

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Answers

by: objectsPosted on 2009-10-19 at 18:55:07ID: 25610497

http://www.java2s.com/Code/Java/Servlets/Servletforlogin.htm

by: l_starter_lPosted on 2009-10-19 at 19:26:02ID: 25610628

I need one with db connectivity

by: objectsPosted on 2009-10-19 at 19:30:58ID: 25610649

why? how the authentication is done is really unrelated
Its just a database query

by: l_starter_lPosted on 2009-10-19 at 20:30:32ID: 25610875

Because I have no experience with coding servlets so I need to see an example with database. I am using a Microsoft access database to store username and passwords

by: objectsPosted on 2009-10-19 at 20:45:41ID: 25610935

you just need to add your database code to the allowUser() method, none of the servlet code needs to change

protected boolean allowUser(String account, String password, String pin) {
// access database here, return true if valid login
return true; // trust everyone
}

by: l_starter_lPosted on 2009-10-19 at 20:55:15ID: 25610966

what would the Sql query be?

by: objectsPosted on 2009-10-19 at 21:33:12ID: 25611079

depends on your schema and whether you want to pull user details from database
simplest case would be something like

select count(*) from users where name=? and passwd=?

or:

select * from users where name=? and passwd=?

replace * with the fields you need

by: l_starter_lPosted on 2009-10-20 at 07:09:30ID: 25614279

"where password =? " what does the ? mean

by: objectsPosted on 2009-10-20 at 15:21:44ID: 25619257

Its a placeholder for use with your PreparedStatement

http://java.sun.com/docs/books/tutorial/jdbc/basics/prepared.html

by: l_starter_lPosted on 2009-10-20 at 16:07:04ID: 25619539

How do I make it check the value in the database if it is not valid check the next value

by: objectsPosted on 2009-10-20 at 16:13:28ID: 25619571

you don't need to check the values at all, the query will only return rows that match

by: l_starter_lPosted on 2009-10-20 at 17:30:46ID: 25619908

Can u check my code the session work but it does not check the database.. it just logs in as null

package login;
 
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
 
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.UnavailableException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpSessionBindingEvent;
import javax.servlet.http.HttpSessionBindingListener;
 
 
 
public class loginserv extends HttpServlet
{
 
 
  public void init(ServletConfig config) throws ServletException {
    super.init(config);
    try {
      // load the driver
      Class.forName("sun.jdbc.odbc.JdbcOdbcDriver").newInstance();
    } catch (ClassNotFoundException e) {
      throw new UnavailableException(
          "Login init() ClassNotFoundException: " + e.getMessage());
    } catch (IllegalAccessException e) {
      throw new UnavailableException(
          "Login init() IllegalAccessException: " + e.getMessage());
    } catch (InstantiationException e) {
      throw new UnavailableException(
          "Login init() InstantiationException: " + e.getMessage());
    }
  }
 
  public void doGet(HttpServletRequest request, HttpServletResponse response)
      throws IOException, ServletException {
 
    response.setContentType("text/html");
    PrintWriter out = response.getWriter();
    out.println("<html>");
    out.println("<head>");
    out.println("<title>Login</title>");
    out.println("</head>");
    out.println("<body>");
 
    HttpSession session = request.getSession();
    SessionConnection sessionConnection = (SessionConnection) session
        .getAttribute("sessionconnection");
    Connection connection = null;
    if (sessionConnection != null) {
      connection = sessionConnection.getConnection();
    }
    if (connection == null) {
      String userName = request.getParameter("username");
         String password = request.getParameter("password");
      if (userName == null || password == null) {
        // prompt the user for her username and password
       out.println("<form method=\"get\" action=\"loginserv\">");
        out.println("Please specify the following to log in:<p>");
        out.println("Username: <input type=\"text\" "
            + "name=\"username\" size=\"30\"><p>");
        out.println("Password: <input type=\"password\" "
            + "name=\"password\" size=\"30\"><p>");
        out.println("<input type=\"submit\" value=\"Login\">");
        out.println("</form>");
      } else {
        // create the connection
        try {
          connection = DriverManager.getConnection(
              "jdbc:odbc:project","","");
        } catch (SQLException e) {
          out.println("Login doGet() " + e.getMessage());
        }
        if (connection != null) {
          // store the connection
          sessionConnection = new SessionConnection();
          sessionConnection.setConnection(connection);
          session
              .setAttribute("sessionconnection",
                  sessionConnection);
         response.sendRedirect("loginserv");
          return;
        }
      }
    } else {
      String logout = request.getParameter("logout");
      if (logout == null) {
        // test the connection
        Statement statement = null;
        ResultSet resultSet = null;
//        String userName1 = null;
       String userName = request.getParameter("username");
        String password = request.getParameter("password");
        String strSQL = "select * from USER_INFO where username = '" + userName + "' and " +"password = '" + password + "'";
         try {
          statement = connection.createStatement();
          resultSet = statement.executeQuery(strSQL );
          if (resultSet.next())
            userName = resultSet.getString(1);
        } catch (SQLException e) {
          out.println("Login doGet() SQLException: " + e.getMessage()
              + "<p>");
        } finally {
          if (resultSet != null)
            try {
              resultSet.close();
            } catch (SQLException ignore) {
            }
          if (statement != null)
            try {
              statement.close();
            } catch (SQLException ignore) {
            }
        }
        out.println("Hello " + userName + "!<p>");
        out.println("Your session ID is " + session.getId() + "<p>");
        out
            .println("It was created on "
                + new java.util.Date(session.getCreationTime())
                + "<p>");
        out.println("It was last accessed on "
            + new java.util.Date(session.getLastAccessedTime())
            + "<p>");
        out.println("<form method=\"get\" action=\"loginserv\">");
        out.println("<input type=\"submit\" name=\"logout\" "
            + "value=\"Logout\">");
        out.println("</form>");
      } else {
        // close the connection and remove it from the session
        try {
          connection.close();
        } catch (SQLException ignore) {
        }
        session.removeAttribute("sessionconnection");
        out.println("You have been logged out.");
      }
    }
    out.println("</body>");
    out.println("</html>");
  }
 
  public void doPost(HttpServletRequest request, HttpServletResponse response)
      throws IOException, ServletException {
    doGet(request, response);
  }
}
 
class SessionConnection implements HttpSessionBindingListener {
 
  Connection connection;
 
  public SessionConnection() {
    connection = null;
  }
 
  public SessionConnection(Connection connection) {
    this.connection = connection;
  }
 
  public Connection getConnection() {
    return connection;
  }
 
  public void setConnection(Connection connection) {
    this.connection = connection;
  }
 
  public void valueBound(HttpSessionBindingEvent event) {
    if (connection != null) {
      System.out.println("Binding a valid connection");
    } else {
      System.out.println("Binding a null connection");
    }
  }
 
  public void valueUnbound(HttpSessionBindingEvent event) {
    if (connection != null) {
      System.out
          .println("Closing the bound connection as the session expires");
      try {
        connection.close();
      } catch (SQLException ignore) {
      }
    }
  }
}

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by: objectsPosted on 2009-10-20 at 18:33:17ID: 25620165

you don't appear to actually store the fact that the user logged in in the session
see the link I posted earlier for an example of how to do that.

by: l_starter_lPosted on 2009-10-22 at 21:38:07ID: 25641391

I wrote this...this code work however it only check the last entry in the database if I try to login with any other it doesn't work

package login;
 
 
import java.io.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;
 
public class LoginAuthentication extends HttpServlet{
 
  private ServletConfig config;
 
  public void init(ServletConfig config)
    throws ServletException{
     this.config=config;
     }
  public void doPost(HttpServletRequest request, HttpServletResponse response)
              throws ServletException,IOException{
 
    PrintWriter out = response.getWriter();
    String connectionURL = "jdbc:odbc:project";
    Connection connection=null;
    ResultSet rs;
    String userName=new String("");
    String passwrd=new String("");
    response.setContentType("text/html");
    try {
       // Load the database driver
      Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
      // Get a Connection to the database
      connection = DriverManager.getConnection(connectionURL, "", "");
      //Add the data into the database
      String sql = "select user,password from USER_INFO";
      Statement s = connection.createStatement();
      s.executeQuery (sql);
      rs = s.getResultSet();
      while (rs.next ()){
        userName=rs.getString("user");
        passwrd=rs.getString("password");
      }
      rs.close ();
      s.close ();
      }catch(Exception e){
      System.out.println("Exception is ;"+e);
      }
      if(userName.equals(request.getParameter("user"))
             && passwrd.equals(request.getParameter("pass"))){
        out.println("WELCOME "+userName);
      }
      else{
        out.println("Please enter correct username and password");
        out.println("<a href='AuthenticLogin.jsp'><br>Login again</a>");
      }
        try {
            connection.close();
        } catch (SQLException ex) {
            System.out.println("Exception is ;"+ex);
        }
  }
}

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Login Servlet with session tracking

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