本文介紹使用CodeIgniter來開發一個用戶登錄和注冊的小模塊，有詳細的數據庫表和ci代碼。

1、數據庫設計

2、文件列表

控制器：Account.php

模型：Maccount.php

視圖：
account/dashboard.php
account/details.php
account/login.php
account/logout.php
account/note.php
account/register.php

3、登錄

a) 控制器

 /**
      * 接收、驗證登錄表單
      * 表單規則在配置文件:/config/form_validation.php
         'account/login'=>array(                        //登錄表單的規則
             array(
                 'field'=>'username',
                 'label'=>'用戶名',
                 'rules'=>'trim|required|xss_clean|callback_username_check'
             ),
             array(
                 'field'=>'password',
                 'label'=>'密碼',
                 'rules'=>'trim|required|xss_clean|callback_password_check'
             )
         )
      * 錯誤提示信息在文件：/system/language/english/form_validation.php
      */
     function login()
     {
         //設置錯誤定界符
         $this->form_validation->set_error_delimiters('<span class="error">', '</span>');
 
         $this->_username = $this->input->post('username');                //用戶名
         if ($this->form_validation->run() == FALSE)
         {
             $this->load->view('account/login');
         }
         else
         {
             //注冊session,設定登錄狀態
             $this->MAccount->login($this->_username);
             $data['message'] = $this->session->userdata('username').' You are logged in! Now take a look at the '
                                 .anchor('account/dashboard', 'Dashboard');
             $this->load->view('account/note', $data);
         }
         }
 
 //登錄表單驗證時自定義的函數
 /**
      * 提示用戶名是不存在的登錄
      * @param string $username
      * @return bool
      */
     function username_check($username)
     {
         if ($this->MAccount->get_by_username($username))
         {
             return TRUE;
         }
         else
         {
             $this->form_validation->set_message('username_check', '用戶名不存在');
             return FALSE;
         }
     }
     /**
      * 檢查用戶的密碼正確性
      */
     function password_check($password)
     {
         $password = md5($this->salt.$password);
         if ($this->MAccount->password_check($this->_username, $password))
         {
             return TRUE;
         }
         else
         {
             $this->form_validation->set_message('password_check', '用戶名或密碼不正確');
             return FALSE;
         }
     }

b) 模型

 /**
      * 添加用戶session數據,設置用戶在線狀態
      * @param string $username
      */
     function login($username)
     {
         $data = array('username'=>$username, 'logged_in'=>TRUE);
         $this->session->set_userdata($data);                    //添加session數據
         }
     /**
      * 通過用戶名獲得用戶記錄
      * @param string $username
      */
     function get_by_username($username)
     {
         $this->db->where('username', $username);
         $query = $this->db->get('user');
         //return $query->row();                            //不判斷獲得什么直接返回
         if ($query->num_rows() == 1)
         {
             return $query->row();
         }
         else
         {
             return FALSE;
         }
     }
    
     /**
      * 用戶名不存在時,返回false
      * 用戶名存在時，驗證密碼是否正確
      */
     function password_check($username, $password)
     {               
         if($user = $this->get_by_username($username))
         {
             return $user->password == $password ? TRUE : FALSE;
         }
         return FALSE;                                    //當用戶名不存在時
     }

c) 視圖

4、注冊

與表單登錄的操作是相似的

a)控制器

 /**
      * 用戶注冊
      * 表單規則在配置文件:/config/form_validation.php
         'account/register'=>array(                    //用戶注冊表單的規則
             array(
                 'field'=>'username',
                 'label'=>'用戶名',
                 'rules'=>'trim|required|xss_clean|callback_username_exists'
             ),
             array(
                 'field'=>'password',
                 'label'=>'密碼',
                 'rules'=>'trim|required|min_length[4]|max_length[12]
 |matches[password_conf]|xss_clean'
             ),
             array(
                 'field'=>'email',
                 'label'=>'郵箱賬號',
                 'rules'=>'trim|required|xss_clean|valid_email|callback_email_exists'
             )
         )
      * 錯誤提示信息在文件：/system/language/english/form_validation.php
      */
     function register()
     {
         //設置錯誤定界符
         $this->form_validation->set_error_delimiters('<span class="error">', '</span>');
        
         if ($this->form_validation->run() == FALSE)
         {
             $this->load->view('account/register');
         }
         else
         {
             $username = $this->input->post('username');
             $password = md5($this->salt.$this->input->post('password'));
             $email = $this->input->post('email');
             if ($this->MAccount->add_user($username, $password, $email))
             {
                 $data['message'] = "The user account has now been created! You can go "
                             .anchor('account/index', 'here').'.';
             }
             else
             {
                 $data['message'] = "There was a problem when adding your account. You can register "
                             .anchor('account/register', 'here').' again.';
             }
             $this->load->view('account/note', $data);
         }       
         }
 /**
      * ======================================
      * 用于注冊表單驗證的函數
      * 1、username_exists()
      * 2、email_exists()
      * ======================================
      */
     /**
      * 驗證用戶名是否被占用。
      * 存在返回false, 否者返回true.
      * @param string $username
      * @return boolean
      */
     function username_exists($username)
     {
         if ($this->MAccount->get_by_username($username))
         {
             $this->form_validation->set_message('username_exists', '用戶名已被占用');
             return FALSE;
         }
         return TRUE;
     }
     function email_exists($email)
     {
         if ($this->MAccount->email_exists($email))
         {
             $this->form_validation->set_message('email_exists', '郵箱已被占用');
             return FALSE;
         }
         return TRUE;
     }

b)模型

     /**
      * 添加用戶
      */
     function add_user($username, $password, $email)
     {
         $data = array('username'=>$username, 'password'=>$password, 'email'=>$email);
         $this->db->insert('user', $data);
         if ($this->db->affected_rows() > 0)
         {
             $this->login($username);
             return TRUE;
         }
         return FALSE;
         }
 /**
      * 檢查郵箱賬號是否存在.
      * @param string $email
      * @return boolean
      */
     function email_exists($email)
     {
         $this->db->where('email', $email);
         $query = $this->db->get('user');
         return $query->num_rows() ? TRUE : FALSE;
     }

5、退出

 /**
      * 用戶退出
      * 已經登錄則退出，否者轉到details
      */
     function logout()
     {
         if ($this->MAccount->logout() == TRUE)
         {
             $this->load->view('account/logout');
         }
         else
         {
             $this->load->view('account/details');
         }
         }

模型：

/**
      * 注銷用戶
      * @return boolean
      */
     function logout()
     {
         if ($this->logged_in() === TRUE)
         {
             $this->session->sess_destroy();                //銷毀所有session的數據
             return TRUE;
         }
         return FALSE;
     }

6、  遺留問題

a) 沒有使用驗證碼

b) 表單規則驗證時，怎樣使當上一個表單某項（如：姓名）出現問題時，停止對后面表單項的驗證（如密碼等）。比如在登錄時，提示用戶名不存在，就沒必要驗證是否填寫了密碼或者密碼有錯誤