<form action="/login" method="POST">
Username: <input type="text" name="username" />
Password: <input type="password" name="password />
<input type="submit" value="Submit">

  
class LoginServlet extends HttpServlet {

  public void doPost(HttpServletRequest request, HttpServletResponse response) {
        // Get the username and password
       String username = request.getParameter("username";
       String password = request.getParameter("password";
   
       try {
          // Get the users information from the database
          String user =  getUserFromDB(username, password);
          // create a session for your newly logged in user
         HttpSession session = request.getSession();
         session.setAttribute("user", user);
         // send user to logged-in page 
         response.sendRedirect("/main";

      } catch(Exception e) {
         // user failed login
         request.setAtrribute("error", "Invalid username or password";
         RequestDispatcher rd = getServletContext().getRequestDispatcher("/login.jsp";
         rd.forward(request, response);
      } 
      
   }

   private String getUserFromDB(String username, String password) throws Exception {
      // This will load the MySQL driver
      Class.forName("com.mysql.jdbc.Driver";
      // Setup the connection with the DB
      Connection connect = DriverManager.getConnection("jdbc:mysql://localhost/database?user=user&password=pw";
      // Statements allow to issue SQL queries to the database
      Statement statement = connect.createStatement();
      ResultSet resultSet = statement.executeQuery("select name from User where username='"+username+"' and password = '"+password+"');
     
     // ResultSet is initially before the first data set
     resultSet.next();

     String user = resultSet.getString("name";
     
      // You need to close the database connections
      if (resultSet != null) {
        resultSet.close();
      }

      if (statement != null) {
        statement.close();
      }

      if (connect != null) {
        connect.close();
      }
     return name;
  }

}

Nov1ce: I think the first question to ask is are you coding for Java Web or Desktop?

danvery2k6: 1. create a table in your database called user or any name of your choice.
2. create two fields of type varchar called username and password with username as the primary key.
3. create a class called UserLogin with username and password as instance variables.
4.create a constructor that initialises these variables.
5. create method login that returns a boolean value and that takes two arguments: user and pass and fetches a row from the database where username = user
6. pass the result and the arguments of the method login to another method verifyUser that returns a boolean eg verifyUser(user, pass, dbUser, dbPass). this method should verify if the database values equal the passed arguments to method login.
hope this helps. still confused? post confusion here
#teamJava

/*
 * For this code snippet to be useful to you. you must first of all do the 
 * follwing
 * 1. Create a table in your database called user or any name.
 * 
 * 2. create fields username(varchar) and password(varchar). set your primary
 * key to username.
 * 
 * 3.connect your database to your application (I'd like to presume you already
 * know how to do that.
 * 
 * 4. And bingo!!!!!!!!! you are ready to work with this piece of code. everything
 * works dandy fine.
 * 
 * 5. Post your confusions here and we will help you sort them out. We presume
 * this is a begginer level tutorial.
 * /////////////////////////////////////////////////////////////////////////
 * Note that the main method is not posted here.
 * make sure mysql-connector/j is included in your project file or you will not
 * able to connect to your database.
 */
package com.court.info.sys;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;

/**
 *
 * @author HP USER
 */
public class Login {
    //the class DBConnect contains the code to connect to your database.
    // My crude attemt at enforcing software reusability.
    DBConnect connection = new DBConnect();//connection class.
    
    /*
     * you need to call this method in your client code. 
     * If it returns true. access can be granted.
     * If it returns false, access shoul not be granted.
   **/
    public boolean userLogin(String user, String pass){
        boolean message = false;
        if((user != null)&&(pass != null)){
            try{
                Connection connect = connection.getConnection();
                String sql = "SELECT username, password FROM user WHERE username"
                        + "= '"+user+"'";
                Statement statement = connect.createStatement();
                ResultSet result = statement.executeQuery(sql);
                while(result.next()){
                    String username = result.getString("username";
                    String password = result.getString("password";
                    message = verifyUser(username, password, user, pass);
                }
            }catch(Exception ex){
               System.err.println(ex.getMessage());
            }
        }
        return message;
    }
    public boolean verifyUser(String dbUser, String dbPass,String user, String pass){
       return (dbUser.equals(user)&&(dbPass.equals(pass)));
    }
    
    
}

xtianh:

my confusion cmes in at stage 5 down could u pls explain in mre details. Thanks fr ur effort