*CI架構裝載器Loader.php源碼分析

http://www.bitscn.com/pdb/php/201411/404680.html

顧名思義，裝載器就是加載元素的，使用CI時，經常加載的有：

$this->load->library()

$this->load->view()

$this->load->model()

$this->load->database()

$this->load->helper()

$this->load->config()

$this->load->add_package_path()

代碼如下:

/**

 * Loader Class

 *

 * 使用者加載views和files，常見的函數有model(),view(),library(),helper()

 * 

 * Controller的好助手，$this->load =& load_class('Loader', 'core');，加載了loader，Controller就無比強大了

 */

class CI_Loader {

 protected $_ci_ob_level;

 protected $_ci_view_paths  = array();

 protected $_ci_library_paths = array();

 protected $_ci_model_paths  = array();

 protected $_ci_helper_paths  = array();

 protected $_base_classes  = array(); // Set by the controller class

 protected $_ci_cached_vars  = array();

 protected $_ci_classes   = array();

 protected $_ci_loaded_files  = array();

 protected $_ci_models   = array();

 protected $_ci_helpers   = array();

 protected $_ci_varmap   = array('unit_test' => 'unit',

           'user_agent' => 'agent');

 public function __construct()

 {       

                //擷取緩沖嵌套級别

  $this->_ci_ob_level  = ob_get_level();

  //library路徑

                $this->_ci_library_paths = array(APPPATH, BASEPATH);

                //helper路徑

  $this->_ci_helper_paths = array(APPPATH, BASEPATH);

                //model路徑

  $this->_ci_model_paths = array(APPPATH);

                //view路徑

  $this->_ci_view_paths = array(APPPATH.'views/' => TRUE);

  log_message('debug', "Loader Class Initialized");

 }

 // --------------------------------------------------------------------

 /**

  * 初始化Loader

  *

  */

 public function initialize()

 {

  $this->_ci_classes = array();

  $this->_ci_loaded_files = array();

  $this->_ci_models = array();

                //将is_loaded（common中記錄加載核心類函數）加載的核心類交給_base_classes

  $this->_base_classes =& is_loaded();

                //加載autoload.php配置中檔案

  $this->_ci_autoloader();

  return $this;

  * 檢測類是否加載

 public function is_loaded($class)

  if (isset($this->_ci_classes[$class]))

  {

   return $this->_ci_classes[$class];

  }

  return FALSE;

  * 加載Class

 public function library($library = '', $params = NULL, $object_name = NULL)

  if (is_array($library))

   foreach ($library as $class)

   {

    $this->library($class, $params);

   }

   return;

                //如果$library為空或者已經加載。。。

  if ($library == '' OR isset($this->_base_classes[$library]))

   return FALSE;

  if ( ! is_null($params) && ! is_array($params))

   $params = NULL;

  $this->_ci_load_class($library, $params, $object_name);

  * 加載和執行個體化model

 public function model($model, $name = '', $db_conn = FALSE)

                //CI支援數組加載多個model

  if (is_array($model))

   foreach ($model as $babe)

    $this->model($babe);

  if ($model == '')

  $path = '';

  // 是否存在子目錄

  if (($last_slash = strrpos($model, '/')) !== FALSE)

   // The path is in front of the last slash

   $path = substr($model, 0, $last_slash + 1);

   // And the model name behind it

   $model = substr($model, $last_slash + 1);

  if ($name == '')

   $name = $model;

  if (in_array($name, $this->_ci_models, TRUE))

  $CI =& get_instance();

  if (isset($CI->$name))

   show_error('The model name you are loading is the name of a resource that is already being used: '.$name);

  $model = strtolower($model); //model檔案名全小寫

  foreach ($this->_ci_model_paths as $mod_path)

   if ( ! file_exists($mod_path.'models/'.$path.$model.'.php'))

    continue;

   if ($db_conn !== FALSE AND ! class_exists('CI_DB'))

    if ($db_conn === TRUE)

    {

     $db_conn = '';

    }

    $CI->load->database($db_conn, FALSE, TRUE);

   if ( ! class_exists('CI_Model'))

    load_class('Model', 'core');

   require_once($mod_path.'models/'.$path.$model.'.php');

   $model = ucfirst($model);

   $CI->$name = new $model();

                        //儲存在Loader::_ci_models中，以後可以用它來判斷某個model是否已經加載過。

   $this->_ci_models[] = $name;

  // couldn't find the model

  show_error('Unable to locate the model you have specified: '.$model);

  * 資料庫Loader

 public function database($params = '', $return = FALSE, $active_record = NULL)

  // Grab the super object

  // 是否需要加載db

  if (class_exists('CI_DB') AND $return == FALSE AND $active_record == NULL AND isset($CI->db) AND is_object($CI->db))

  require_once(BASEPATH.'database/DB.php');

  if ($return === TRUE)

   return DB($params, $active_record);

  // Initialize the db variable.  Needed to prevent

  // reference errors with some configurations

  $CI->db = '';

  // Load the DB class

  $CI->db =& DB($params, $active_record);

  * 加載資料庫工具類

 public function dbutil()

  if ( ! class_exists('CI_DB'))

   $this->database();

  // for backwards compatibility, load dbforge so we can extend dbutils off it

  // this use is deprecated and strongly discouraged

  $CI->load->dbforge();

  require_once(BASEPATH.'database/DB_utility.php');

  require_once(BASEPATH.'database/drivers/'.$CI->db->dbdriver.'/'.$CI->db->dbdriver.'_utility.php');

  $class = 'CI_DB_'.$CI->db->dbdriver.'_utility';

  $CI->dbutil = new $class();

  * Load the Database Forge Class

  * @return string

 public function dbforge()

  require_once(BASEPATH.'database/DB_forge.php');

  require_once(BASEPATH.'database/drivers/'.$CI->db->dbdriver.'/'.$CI->db->dbdriver.'_forge.php');

  $class = 'CI_DB_'.$CI->db->dbdriver.'_forge';

  $CI->dbforge = new $class();

  * 加載視圖檔案

 public function view($view, $vars = array(), $return = FALSE)

  return $this->_ci_load(array('_ci_view' => $view, '_ci_vars' => $this->_ci_object_to_array($vars), '_ci_return' => $return));

  * 加載普通檔案

 public function file($path, $return = FALSE)

  return $this->_ci_load(array('_ci_path' => $path, '_ci_return' => $return));

  * 設定變量

  * Once variables are set they become available within

  * the controller class and its "view" files.

 public function vars($vars = array(), $val = '')

  if ($val != '' AND is_string($vars))

   $vars = array($vars => $val);

  $vars = $this->_ci_object_to_array($vars);

  if (is_array($vars) AND count($vars) > 0)

   foreach ($vars as $key => $val)

    $this->_ci_cached_vars[$key] = $val;

  * 檢查并擷取變量

 public function get_var($key)

  return isset($this->_ci_cached_vars[$key]) ? $this->_ci_cached_vars[$key] : NULL;

  * 加載helper

 public function helper($helpers = array())

  foreach ($this->_ci_prep_filename($helpers, '_helper') as $helper)

   if (isset($this->_ci_helpers[$helper]))

   $ext_helper = APPPATH.'helpers/'.config_item('subclass_prefix').$helper.'.php';

   // 如果是擴充helper的話

   if (file_exists($ext_helper))

    $base_helper = BASEPATH.'helpers/'.$helper.'.php';

    if ( ! file_exists($base_helper))

     show_error('Unable to load the requested file: helpers/'.$helper.'.php');

    include_once($ext_helper);

    include_once($base_helper);

    $this->_ci_helpers[$helper] = TRUE;

    log_message('debug', 'Helper loaded: '.$helper);

   // 如果不是擴充helper，helper路徑中加載helper

   foreach ($this->_ci_helper_paths as $path)

    if (file_exists($path.'helpers/'.$helper.'.php'))

     include_once($path.'helpers/'.$helper.'.php');

     $this->_ci_helpers[$helper] = TRUE;

     log_message('debug', 'Helper loaded: '.$helper);

     break;

   // 如果該helper還沒加載成功的話，說明加載helper失敗

   if ( ! isset($this->_ci_helpers[$helper]))

    show_error('Unable to load the requested file: helpers/'.$helper.'.php');

  * 可以看到helpers調用也是上面的helper,隻是helpers的别名而已

 public function helpers($helpers = array())

  $this->helper($helpers);

  * 加載language檔案

 public function language($file = array(), $lang = '')

  if ( ! is_array($file))

   $file = array($file);

  foreach ($file as $langfile)

   $CI->lang->load($langfile, $lang);

  * 加載配置檔案

 public function config($file = '', $use_sections = FALSE, $fail_gracefully = FALSE)

  $CI->config->load($file, $use_sections, $fail_gracefully);

  * Driver

  * 加載 driver library

 public function driver($library = '', $params = NULL, $object_name = NULL)

  if ( ! class_exists('CI_Driver_Library'))

   // we aren't instantiating an object here, that'll be done by the Library itself

   require BASEPATH.'libraries/Driver.php';

  if ($library == '')

  // We can save the loader some time since Drivers will *always* be in a subfolder,

  // and typically identically named to the library

  if ( ! strpos($library, '/'))

   $library = ucfirst($library).'/'.$library;

  return $this->library($library, $params, $object_name);

  * 添加 Package 路徑

  * 把package路徑添加到庫，模型，助手，配置路徑

 public function add_package_path($path, $view_cascade=TRUE)

  $path = rtrim($path, '/').'/';

  array_unshift($this->_ci_library_paths, $path);

  array_unshift($this->_ci_model_paths, $path);

  array_unshift($this->_ci_helper_paths, $path);

  $this->_ci_view_paths = array($path.'views/' => $view_cascade) + $this->_ci_view_paths;

  $config =& $this->_ci_get_component('config');

  array_unshift($config->_config_paths, $path);

  * 擷取Package Paths，預設不包含BASEPATH

 public function get_package_paths($include_base = FALSE)

  return $include_base === TRUE ? $this->_ci_library_paths : $this->_ci_model_paths;

  * 剔除Package Path

  * Remove a path from the library, model, and helper path arrays if it exists

  * If no path is provided, the most recently added path is removed.

 public function remove_package_path($path = '', $remove_config_path = TRUE)

  if ($path == '')

   $void = array_shift($this->_ci_library_paths);

   $void = array_shift($this->_ci_model_paths);

   $void = array_shift($this->_ci_helper_paths);

   $void = array_shift($this->_ci_view_paths);

   $void = array_shift($config->_config_paths);

  else

   $path = rtrim($path, '/').'/';

   foreach (array('_ci_library_paths', '_ci_model_paths', '_ci_helper_paths') as $var)

    if (($key = array_search($path, $this->{$var})) !== FALSE)

     unset($this->{$var}[$key]);

   if (isset($this->_ci_view_paths[$path.'views/']))

    unset($this->_ci_view_paths[$path.'views/']);

   if (($key = array_search($path, $config->_config_paths)) !== FALSE)

    unset($config->_config_paths[$key]);

  // 保證應用預設的路徑依然存在

  $this->_ci_library_paths = array_unique(array_merge($this->_ci_library_paths, array(APPPATH, BASEPATH)));

  $this->_ci_helper_paths = array_unique(array_merge($this->_ci_helper_paths, array(APPPATH, BASEPATH)));

  $this->_ci_model_paths = array_unique(array_merge($this->_ci_model_paths, array(APPPATH)));

  $this->_ci_view_paths = array_merge($this->_ci_view_paths, array(APPPATH.'views/' => TRUE));

  $config->_config_paths = array_unique(array_merge($config->_config_paths, array(APPPATH)));

  * Loader

  * This function is used to load views and files.

  * Variables are prefixed with _ci_ to avoid symbol collision with

  * variables made available to view files

  * @param array

  * @return void

 protected function _ci_load($_ci_data)

  // Set the default data variables

  foreach (array('_ci_view', '_ci_vars', '_ci_path', '_ci_return') as $_ci_val)

   $$_ci_val = ( ! isset($_ci_data[$_ci_val])) ? FALSE : $_ci_data[$_ci_val];

  $file_exists = FALSE;

                //如果$_ci_path不為空，則說明目前要加載普通檔案。Loader::file才會有path

  if ($_ci_path != '')

   $_ci_x = explode('/', $_ci_path);

   $_ci_file = end($_ci_x);

   $_ci_ext = pathinfo($_ci_view, PATHINFO_EXTENSION);

   $_ci_file = ($_ci_ext == '') ? $_ci_view.'.php' : $_ci_view;

   foreach ($this->_ci_view_paths as $view_file => $cascade)

    if (file_exists($view_file.$_ci_file))

     $_ci_path = $view_file.$_ci_file;

     $file_exists = TRUE;

    if ( ! $cascade)

                //view檔案不存在則會報錯

  if ( ! $file_exists && ! file_exists($_ci_path))

   show_error('Unable to load the requested file: '.$_ci_file);

  // 把CI的所有屬性都傳遞給loader，view中$this指的是loader

  $_ci_CI =& get_instance();

  foreach (get_object_vars($_ci_CI) as $_ci_key => $_ci_var)

   if ( ! isset($this->$_ci_key))

    $this->$_ci_key =& $_ci_CI->$_ci_key;

  /*

   * Extract and cache variables

   *

   * You can either set variables using the dedicated $this->load_vars()

   * function or via the second parameter of this function. We'll merge

   * the two types and cache them so that views that are embedded within

   * other views can have access to these variables.

   */

  if (is_array($_ci_vars))

   $this->_ci_cached_vars = array_merge($this->_ci_cached_vars, $_ci_vars);

  extract($this->_ci_cached_vars);

   * 将視圖内容放到緩存區

  ob_start();

  // 支援短标簽

  if ((bool) @ini_get('short_open_tag') === FALSE AND config_item('rewrite_short_tags') == TRUE)

   echo eval('?>'.preg_replace("/;*\s*\?>/", "; ?>", str_replace('<?=', '<?php echo ', file_get_contents($_ci_path))));

   include($_ci_path); // include() vs include_once() allows for multiple views with the same name

  log_message('debug', 'File loaded: '.$_ci_path);

  // 是否直接傳回view資料

  if ($_ci_return === TRUE)

   $buffer = ob_get_contents();

   @ob_end_clean();

   return $buffer;

  //目前這個視圖檔案是被另一個視圖檔案通過$this->view()方法引入，即視圖檔案嵌入視圖檔案

  if (ob_get_level() > $this->_ci_ob_level + 1)

   ob_end_flush();

  {       ////把緩沖區的内容交給Output元件并清空關閉緩沖區。

   $_ci_CI->output->append_output(ob_get_contents());

  * 加載類

 protected function _ci_load_class($class, $params = NULL, $object_name = NULL)

  // 去掉.php和兩端的/擷取的$class就是類名或目錄名+類名

  $class = str_replace('.php', '', trim($class, '/'));

  // CI允許dir/filename方式

  $subdir = '';

  if (($last_slash = strrpos($class, '/')) !== FALSE)

   // 目錄

   $subdir = substr($class, 0, $last_slash + 1);

   // 檔案名

   $class = substr($class, $last_slash + 1);

  // 允許加載的類名首字母大寫或全小寫

  foreach (array(ucfirst($class), strtolower($class)) as $class)

   $subclass = APPPATH.'libraries/'.$subdir.config_item('subclass_prefix').$class.'.php';

   // 是否是擴充類

   if (file_exists($subclass))

    $baseclass = BASEPATH.'libraries/'.ucfirst($class).'.php';

    if ( ! file_exists($baseclass))

     log_message('error', "Unable to load the requested class: ".$class);

     show_error("Unable to load the requested class: ".$class);

    // Safety:  Was the class already loaded by a previous call?

    if (in_array($subclass, $this->_ci_loaded_files))

     // Before we deem this to be a duplicate request, let's see

     // if a custom object name is being supplied.  If so, we'll

     // return a new instance of the object

     if ( ! is_null($object_name))

     {

      $CI =& get_instance();

      if ( ! isset($CI->$object_name))

      {

       return $this->_ci_init_class($class, config_item('subclass_prefix'), $params, $object_name);

      }

     }

     $is_duplicate = TRUE;

     log_message('debug', $class." class already loaded. Second attempt ignored.");

     return;

    include_once($baseclass);

    include_once($subclass);

    $this->_ci_loaded_files[] = $subclass;

                                //執行個體化類

    return $this->_ci_init_class($class, config_item('subclass_prefix'), $params, $object_name);

   // 如果不是擴充，和上面類似

   $is_duplicate = FALSE;

   foreach ($this->_ci_library_paths as $path)

    $filepath = $path.'libraries/'.$subdir.$class.'.php';

    // Does the file exist?  No?  Bummer...

    if ( ! file_exists($filepath))

     continue;

    if (in_array($filepath, $this->_ci_loaded_files))

       return $this->_ci_init_class($class, '', $params, $object_name);

    include_once($filepath);

    $this->_ci_loaded_files[] = $filepath;

    return $this->_ci_init_class($class, '', $params, $object_name);

  } // END FOREACH

  // 如果還沒有找到該class，最後的嘗試是該class會不會在同名的子目錄下

  if ($subdir == '')

   $path = strtolower($class).'/'.$class;

   return $this->_ci_load_class($path, $params);

  // 加載失敗，報錯

  if ($is_duplicate == FALSE)

   log_message('error', "Unable to load the requested class: ".$class);

   show_error("Unable to load the requested class: ".$class);

  * 執行個體化已經加載的類

 protected function _ci_init_class($class, $prefix = '', $config = FALSE, $object_name = NULL)

  // 是否有類的配置資訊

  if ($config === NULL)

   // Fetch the config paths containing any package paths

   $config_component = $this->_ci_get_component('config');

   if (is_array($config_component->_config_paths))

    // Break on the first found file, thus package files

    // are not overridden by default paths

    foreach ($config_component->_config_paths as $path)

     // We test for both uppercase and lowercase, for servers that

     // are case-sensitive with regard to file names. Check for environment

     // first, global next

     if (defined('ENVIRONMENT') AND file_exists($path .'config/'.ENVIRONMENT.'/'.strtolower($class).'.php'))

      include($path .'config/'.ENVIRONMENT.'/'.strtolower($class).'.php');

      break;

     elseif (defined('ENVIRONMENT') AND file_exists($path .'config/'.ENVIRONMENT.'/'.ucfirst(strtolower($class)).'.php'))

      include($path .'config/'.ENVIRONMENT.'/'.ucfirst(strtolower($class)).'.php');

     elseif (file_exists($path .'config/'.strtolower($class).'.php'))

      include($path .'config/'.strtolower($class).'.php');

     elseif (file_exists($path .'config/'.ucfirst(strtolower($class)).'.php'))

      include($path .'config/'.ucfirst(strtolower($class)).'.php');

  if ($prefix == '')

  {       //system下library

   if (class_exists('CI_'.$class))

    $name = 'CI_'.$class;

   elseif (class_exists(config_item('subclass_prefix').$class))

   {       //擴充library

    $name = config_item('subclass_prefix').$class;

   else

    $name = $class;

   $name = $prefix.$class;

  // Is the class name valid?

  if ( ! class_exists($name))

   log_message('error', "Non-existent class: ".$name);

   show_error("Non-existent class: ".$class);

  // Set the variable name we will assign the class to

  // Was a custom class name supplied?  If so we'll use it

  $class = strtolower($class);

  if (is_null($object_name))

   $classvar = ( ! isset($this->_ci_varmap[$class])) ? $class : $this->_ci_varmap[$class];

   $classvar = $object_name;

  // Save the class name and object name

  $this->_ci_classes[$class] = $classvar;

  // 将初始化的類的執行個體給CI超級句柄

  if ($config !== NULL)

   $CI->$classvar = new $name($config);

   $CI->$classvar = new $name;

  * 自動加載器

         * 

         * autoload.php配置的自動加載檔案有：

         *  | 1. Packages

            | 2. Libraries

            | 3. Helper files

            | 4. Custom config files

            | 5. Language files

            | 6. Models

 private function _ci_autoloader()

  if (defined('ENVIRONMENT') AND file_exists(APPPATH.'config/'.ENVIRONMENT.'/autoload.php'))

   include(APPPATH.'config/'.ENVIRONMENT.'/autoload.php');

   include(APPPATH.'config/autoload.php');

  if ( ! isset($autoload))

  // 自動加載packages,也就是将package_path加入到library，model，helper，config

  if (isset($autoload['packages']))

   foreach ($autoload['packages'] as $package_path)

    $this->add_package_path($package_path);

  // 加載config檔案

  if (count($autoload['config']) > 0)

   $CI =& get_instance();

   foreach ($autoload['config'] as $key => $val)

    $CI->config->load($val);

  // 加載helper和language

  foreach (array('helper', 'language') as $type)

   if (isset($autoload[$type]) AND count($autoload[$type]) > 0)

    $this->$type($autoload[$type]);

  // 這個好像是為了相容以前版本的

  if ( ! isset($autoload['libraries']) AND isset($autoload['core']))

   $autoload['libraries'] = $autoload['core'];

  // 加載libraries

  if (isset($autoload['libraries']) AND count($autoload['libraries']) > 0)

   // 加載db

   if (in_array('database', $autoload['libraries']))

    $this->database();

    $autoload['libraries'] = array_diff($autoload['libraries'], array('database'));

   // 加載所有其他libraries

   foreach ($autoload['libraries'] as $item)

    $this->library($item);

  // Autoload models

  if (isset($autoload['model']))

   $this->model($autoload['model']);

  * 傳回由對象屬性組成的關聯數組

 protected function _ci_object_to_array($object)

  return (is_object($object)) ? get_object_vars($object) : $object;

  * 擷取CI某個元件的執行個體

 protected function &_ci_get_component($component)

  return $CI->$component;

  * 處理檔案名，這個函數主要是傳回正确檔案名

 protected function _ci_prep_filename($filename, $extension)

  if ( ! is_array($filename))

   return array(strtolower(str_replace('.php', '', str_replace($extension, '', $filename)).$extension));

   foreach ($filename as $key => $val)

    $filename[$key] = strtolower(str_replace('.php', '', str_replace($extension, '', $val)).$extension);

   return $filename;

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