CodeIgniter 核心代码阅读-程序启动文件CodeIgniter.php

CodeIgniter.php----加载需要的类库，CI框架所有操作都在这里执行

一个简单的页面需要加载的类库如下所示：

    [0] => D:\wamp\www\CodeIgniter_2.1.3\system\core\CodeIgniter.php    [1] => D:\wamp\www\CodeIgniter_2.1.3\system\core\Common.php    [2] => D:\wamp\www\CodeIgniter_2.1.3\system\core\Benchmark.php    [3] => D:\wamp\www\CodeIgniter_2.1.3\system\core\Hooks.php    [4] => D:\wamp\www\CodeIgniter_2.1.3\system\core\Config.php    [5] => D:\wamp\www\CodeIgniter_2.1.3\system\core\Utf8.php    [6] => D:\wamp\www\CodeIgniter_2.1.3\system\core\URI.php    [7] => D:\wamp\www\CodeIgniter_2.1.3\system\core\Router.php    [8] => D:\wamp\www\CodeIgniter_2.1.3\system\core\Output.php    [9] => D:\wamp\www\CodeIgniter_2.1.3\system\core\Security.php    [10] => D:\wamp\www\CodeIgniter_2.1.3\system\core\Input.php    [11] => D:\wamp\www\CodeIgniter_2.1.3\system\core\Lang.php    [12] => D:\wamp\www\CodeIgniter_2.1.3\system\core\Controller.php    [13] => D:\wamp\www\CodeIgniter_2.1.3\system\core\Loader.php    [14] => D:\wamp\www\CodeIgniter_2.1.3\system\core\Model.php    [15] => D:\wamp\www\CodeIgniter_2.1.3\system\database\DB.php    [16] => D:\wamp\www\CodeIgniter_2.1.3\system\database\DB_driver.php    [17] => D:\wamp\www\CodeIgniter_2.1.3\system\database\DB_active_rec.php    [18] => D:\wamp\www\CodeIgniter_2.1.3\system\database\drivers\mysql\mysql_driver.php    [19] => D:\wamp\www\CodeIgniter_2.1.3\application\config\constants.php    [20] => D:\wamp\www\CodeIgniter_2.1.3\application\config\config.php    [21] => D:\wamp\www\CodeIgniter_2.1.3\application\config\routes.php    [22] => D:\wamp\www\CodeIgniter_2.1.3\application\config\mimes.php    [23] => D:\wamp\www\CodeIgniter_2.1.3\application\controllers\news.php    [24] => D:\wamp\www\CodeIgniter_2.1.3\application\config\autoload.php    [25] => D:\wamp\www\CodeIgniter_2.1.3\application\models\news_model.php    [26] => D:\wamp\www\CodeIgniter_2.1.3\application\config\database.php

CodeIgniter核心类库加载顺序：

Common.php->Benchmark.php->Hooks.php->Config.php->Utf8.php->URI.php->Router.php->Output.php->Securit.php->Input.php->Lang.php->Controller.php->Loader.php

CodeIgniter.php源码：

<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');//ci版本号define('CI_VERSION', '2.1.3');//ci分支define('CI_CORE', FALSE);//加载全局函数require(BASEPATH.'core/Common.php');//加载框架定义的常量，可在APPPATH.'config/constants.php'文件中定义常量if (defined('ENVIRONMENT') AND file_exists(APPPATH.'config/'.ENVIRONMENT.'/constants.php')){require(APPPATH.'config/'.ENVIRONMENT.'/constants.php');}else{require(APPPATH.'config/constants.php');}//定义错误处理句柄set_error_handler('_exception_handler');//关闭魔术引号，本特性已自 PHP 5.3.0 起废弃并将自 PHP 5.4.0 起移除。if ( ! is_php('5.3')){@set_magic_quotes_runtime(0); // Kill magic quotes}//设置类前缀名if (isset($assign_to_config['subclass_prefix']) AND $assign_to_config['subclass_prefix'] != ''){get_config(array('subclass_prefix' => $assign_to_config['subclass_prefix']));}//设置PHP脚本的最大执行时间if (function_exists("set_time_limit") == TRUE AND @ini_get("safe_mode") == 0){@set_time_limit(300);}//实例化计时类$BM =& load_class('Benchmark', 'core');$BM->mark('total_execution_time_start');$BM->mark('loading_time:_base_classes_start');//实例化钩子类$EXT =& load_class('Hooks', 'core');//钩子--仅仅在benchmark 和 hooks 类 加载完毕的时候. 没有执行路由或者其它的过程.$EXT->_call_hook('pre_system');//实例化config类$CFG =& load_class('Config', 'core');// Do we have any manually set config items in the index.php file?if (isset($assign_to_config)){$CFG->_assign_to_config($assign_to_config);}//实例化UTF-8类$UNI =& load_class('Utf8', 'core');//实例化URI类$URI =& load_class('URI', 'core');//实例化Router类,并设置路由$RTR =& load_class('Router', 'core');$RTR->_set_routing();// Set any routing overrides that may exist in the main index fileif (isset($routing)){$RTR->_set_overrides($routing);}//实例化Output类$OUT =& load_class('Output', 'core');//是否已经缓存了文件if ($EXT->_call_hook('cache_override') === FALSE){       if ($OUT->_display_cache($CFG, $URI) == TRUE)       {           exit;       }}//实例化Security类$SEC =& load_class('Security', 'core');//实例化Input类$IN =& load_class('Input', 'core');//实例化Lang类$LANG =& load_class('Lang', 'core');//加载CI_Controller类require BASEPATH.'core/Controller.php';function &get_instance(){return CI_Controller::get_instance();}//加载应用程序Controller类if (file_exists(APPPATH.'core/'.$CFG->config['subclass_prefix'].'Controller.php')){require APPPATH.'core/'.$CFG->config['subclass_prefix'].'Controller.php';}if ( ! file_exists(APPPATH.'controllers/'.$RTR->fetch_directory().$RTR->fetch_class().'.php')){show_error('Unable to load your default controller. Please make sure the controller specified in your Routes.php file is valid.');}include(APPPATH.'controllers/'.$RTR->fetch_directory().$RTR->fetch_class().'.php');// Set a mark point for benchmarking$BM->mark('loading_time:_base_classes_end');//安全检查如果控制器不存在或者方法名不存在，则显示404//控制器类名$class  = $RTR->fetch_class();//控制器方法名$method = $RTR->fetch_method();if ( ! class_exists($class)OR strncmp($method, '_', 1) == 0OR in_array(strtolower($method), array_map('strtolower', get_class_methods('CI_Controller')))){if ( ! empty($RTR->routes['404_override'])){$x = explode('/', $RTR->routes['404_override']);$class = $x[0];$method = (isset($x[1]) ? $x[1] : 'index');if ( ! class_exists($class)){if ( ! file_exists(APPPATH.'controllers/'.$class.'.php')){show_404("{$class}/{$method}");}include_once(APPPATH.'controllers/'.$class.'.php');}}else{show_404("{$class}/{$method}");}}//钩子--在调用任何控制器之前调用.此时所用的基础类,路由选择和安全性检查都已完成.$EXT->_call_hook('pre_controller');//实例化请求的控制器// Mark a start point so we can benchmark the controller$BM->mark('controller_execution_time_( '.$class.' / '.$method.' )_start');$CI = new $class();//钩子--在控制器实例化之后,任何方法调用之前调用.$EXT->_call_hook('post_controller_constructor');//执行请求的方法//如果控制器中定义了_remap方法，则执行remap方法if (method_exists($CI, '_remap')){$CI->_remap($method, array_slice($URI->rsegments, 2));}else{// is_callable() returns TRUE on some versions of PHP 5 for private and protected// methods, so we'll use this workaround for consistent behaviorif ( ! in_array(strtolower($method), array_map('strtolower', get_class_methods($CI)))){// Check and see if we are using a 404 override and use it.if ( ! empty($RTR->routes['404_override'])){$x = explode('/', $RTR->routes['404_override']);$class = $x[0];$method = (isset($x[1]) ? $x[1] : 'index');if ( ! class_exists($class)){if ( ! file_exists(APPPATH.'controllers/'.$class.'.php')){show_404("{$class}/{$method}");}include_once(APPPATH.'controllers/'.$class.'.php');unset($CI);$CI = new $class();}}else{show_404("{$class}/{$method}");}}// Call the requested method.// Any URI segments present (besides the class/function) will be passed to the method for conveniencecall_user_func_array(array(&$CI, $method), array_slice($URI->rsegments, 2));}// Mark a benchmark end point$BM->mark('controller_execution_time_( '.$class.' / '.$method.' )_end');//钩子--在控制器完全运行之后调用.$EXT->_call_hook('post_controller');//输出显示内容if ($EXT->_call_hook('display_override') === FALSE){$OUT->_display();}//钩子--在最终渲染页面发送到浏览器之后,浏览器接收完最终数据的系统执行末尾调用$EXT->_call_hook('post_system');//关闭数据路连接if (class_exists('CI_DB') AND isset($CI->db)){$CI->db->close();}