CI框架源码阅读---------钩子类hooks.php

<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');/** * CodeIgniter * * An open source application development framework for PHP 5.1.6 or newer * * @packageCodeIgniter * @authorExpressionEngine Dev Team * @copyrightCopyright (c) 2008 - 2011, EllisLab, Inc. * @licensehttp://codeigniter.com/user_guide/license.html * @linkhttp://codeigniter.com * @sinceVersion 1.0 * @filesource */// ------------------------------------------------------------------------/** * CodeIgniter Hooks Class * * Provides 提供 a mechanism 机制 to extend the base system without hacking. * 用户手册地址：http://codeigniter.org.cn/user_guide/general/hooks.html * @packageCodeIgniter * @subpackageLibraries * @categoryLibraries * @authorExpressionEngine Dev Team * @linkhttp://codeigniter.com/user_guide/libraries/encryption.html */class CI_Hooks {/** * Determines wether hooks are enabled * 决定钩子是否启用 * * @var bool */var $enabled= FALSE;/** * List of all hooks set in config/hooks.php * * @var array */var $hooks= array();/** * Determines wether hook is in progress, used to prevent 防止 infinte 无限 loops * * @var bool */var $in_progress= FALSE;/** * Constructor * */function __construct(){$this->_initialize();log_message('debug', "Hooks Class Initialized");}// --------------------------------------------------------------------/** * Initialize the Hooks Preferences 参数，首选项 * 初始化钩子 * @accessprivate * @returnvoid */function _initialize(){$CFG =& load_class('Config', 'core');// If hooks are not enabled in the config file// there is nothing else to do// 如果配置文件中设置了是不允许hooks，则直接返回退出本函数。if ($CFG->item('enable_hooks') == FALSE){return;}// Grab the "hooks" definition file.// 抓取钩子的定义文件// If there are no hooks, we're done.// 如果没有定义hooks.php没有定义$hook数组我们直接返回if (defined('ENVIRONMENT') AND is_file(APPPATH.'config/'.ENVIRONMENT.'/hooks.php')){    include(APPPATH.'config/'.ENVIRONMENT.'/hooks.php');}elseif (is_file(APPPATH.'config/hooks.php')){include(APPPATH.'config/hooks.php');}if ( ! isset($hook) OR ! is_array($hook)){return;}// 将hooks.php 中的$hook数组引用到$this->hooks// 开启$this->enabled$this->hooks =& $hook;$this->enabled = TRUE;}// --------------------------------------------------------------------/** * Call Hook * 外部其实就是调用这个_call_hook函数进行调用钩子程序。 * 而此方法中再调用_run_hook去执行相应的钩子。 * Calls a particular hook * * @accessprivate * @paramstringthe hook name * @returnmixed */function _call_hook($which = ''){// 判断$this->enabled 是否开启 和 要调用的钩子是否在$htis->hooks中存在。if ( ! $this->enabled OR ! isset($this->hooks[$which])){return FALSE;}// 判断要调用的钩子是否是一个二维数组，如果是就遍历执行。// 如果不是二维数组就直接执行// 这里说明，在一个挂钩点可以执行多个钩子，就是通过定义二维数组来实现的。if (isset($this->hooks[$which][0]) AND is_array($this->hooks[$which][0])){foreach ($this->hooks[$which] as $val){$this->_run_hook($val);}}else{$this->_run_hook($this->hooks[$which]);}return TRUE;}// --------------------------------------------------------------------/** * Run Hook * 运行钩子 * Runs a particular 特别的 hook *  * @accessprivate * @paramarraythe hook details * @returnbool */function _run_hook($data){/* * $data 就是我们在APPPATH/config/hook.php 定义的hook数组         * $hook['pre_controller'] = array(         *        'class'    => 'MyClass',         *        'function' => 'Myfunction',         *        'filename' => 'Myclass.php',         *        'filepath' => 'hooks',         *        'params'   => array('beer', 'wine', 'snacks')         *         ); * * 由于每一个钩子肯定是由数组组成的 * 所以这里就判断$data是不是数组如果不是则返回 *  */if ( ! is_array($data)){return FALSE;}// -----------------------------------// Safety - Prevents run-away loops// -----------------------------------// If the script being called happens to have the same// hook call within it a loop can happen// 如果调用某一个hook，执行某些脚本，而有可能这些脚本里面再会触发其它hook// 如果这个其它hook里面又包含了当前// 的hook，那么就会进入死循环，这个in_progress的存在就是阻止这种情况。if ($this->in_progress == TRUE){return;}// -----------------------------------// 取出data里面的数据，加载  APPPATH.$data['filepath'].$data['filename'];        // Set file path// -----------------------------------if ( ! isset($data['filepath']) OR ! isset($data['filename'])){return FALSE;}$filepath = APPPATH.$data['filepath'].'/'.$data['filename'];if ( ! file_exists($filepath)){return FALSE;}// -----------------------------------// Set class/function name// -----------------------------------$class= FALSE;$function= FALSE;$params= '';// 取出$hooks 中的class function params if (isset($data['class']) AND $data['class'] != ''){$class = $data['class'];}if (isset($data['function'])){$function = $data['function'];}if (isset($data['params'])){$params = $data['params'];}if ($class === FALSE AND $function === FALSE){return FALSE;}// -----------------------------------// Set the in_progress flag// 在开始执行钩子相应的程序之前，先把当前hook的状态设为正在运行中。// -----------------------------------$this->in_progress = TRUE;// -----------------------------------// Call the requested class and/or function// 包含钩子文件并实例化类，调用函数// -----------------------------------if ($class !== FALSE){if ( ! class_exists($class)){require($filepath);}$HOOK = new $class;$HOOK->$function($params);}else{if ( ! function_exists($function)){require($filepath);}$function($params);}// 执行相应程序完毕后，重新把当前hook的状态改为非运行中// 以让它可以再次被触发。$this->in_progress = FALSE;return TRUE;}}// END CI_Hooks class/* End of file Hooks.php *//* Location: ./system/core/Hooks.php */