CI框架源码阅读----程序入口文件
最近在学习CI框架，自己在按照代码执行顺序阅读源码。做了一些笔记。与其自己珍藏不如拿出来和大家分享
本人并非大牛，是一名处于成长初期的phper，难免有错误的地方。还希望大家能给予指正。
我的CI版本是2.1.3
csdn好像不能上传文件，我就讲代码放在笔记下面了。
如果觉得能对您有一些可以经常来看，我会不定期更新。知道读完CI源码
程序入口：
1、 应用程序环境设置development testing production 可以设置这三种环境
2、 对不同的环境应用不同的错误级别
3、 设置系统文件夹名
4、 设置应用程序文件夹名
5、 设置默认控制器（这里被注释掉了，如果想设置直接开启）
6、 设置自定义配置
7、 增强system path的可靠性
a) 设置当前目录保证正确的请求
b) 保证目录后面有/
c) 判断当前系统路径是否存在
8、 开始设置主路径常量
SELF 当前文件的路径
EXT 文件扩展名
BASEPATH 系统路径
FCPATH 前端控制器路径
SYSDIR 系统文件夹路径
APPPATH 应用程序文件夹路径
9、调用BASEPATH.'core/CodeIgniter.php'文件进入系统引导程序
<?php/* *--------------------------- * APPLICATION ENVIRONMENT *--------------------------- * * You can load different configurations depending on your * current environment. Setting the environment also influences * things like logging and error reporting. * * This can be set to anything, but default usage is: * * development * testing * production * * NOTE: If you change these, also change the error_reporting() code below * */define('ENVIRONMENT', 'development');/* *--------------------------- * ERROR REPORTING *--------------------------- * * Different environments will require different levels of error reporting. * By default development will show errors but testing and live will hide them. */if (defined('ENVIRONMENT')){switch (ENVIRONMENT){case 'development':error_reporting(E_ALL);break;case 'testing':case 'production':error_reporting(0);break;default:exit('The application environment is not set correctly.');}}/* *--------------------------- * SYSTEM FOLDER NAME *--------------------------- * * This variable must contain the name of your "system" folder. * Include the path if the folder is not in the same directory * as this file. * */$system_path = 'system';/* *--------------------------- * APPLICATION FOLDER NAME *--------------------------- * * If you want this front controller to use a different "application" * folder then the default one you can set its name here. The folder * can also be renamed or relocated anywhere on your server. If * you do, use a full server path. For more info please see the user guide: * http://codeigniter.com/user_guide/general/managing_apps.html * * NO TRAILING SLASH! * */$application_folder = 'application';/* * -------------------------------- * DEFAULT CONTROLLER * -------------------------------- * * Normally you will set your default controller in the routes.php file. * You can, however, force a custom routing by hard-coding a specific * controller class/function here. For most applications, you * WILL NOT set your routing here, but it's an option for those 那些 * special 特殊 instances where you might 可能 want to override the standard 标准 * routing in a specific 明确的 front 前面 controller that shares a common CI installation. * * IMPORTANT: 重要的 If you set the routing here, NO OTHER controller will be * callable. 可赎回的 In essence,本质 this preference 偏好、倾向、优先权 limits 范围、限制 * your application to ONE specific controller. * Leave 许可、离开、留下 the function name blank空白，消失 if you need * to call functions dynamically 动态的 via 通过 the URI. * * Un-comment the $routing array below 在下面 to use this feature 特色，特写，起重要作用 * */// The directory name, relative 相关的 to the "controllers" folder. Leave blank// if your controller is not in a sub-folder 代替-文件夹 within 在。。。之内 // the "controllers" folder// $routing['directory'] = '';// The controller class file name. Example: Mycontroller// $routing['controller'] = '';// The controller function you wish 希望 to be called.// $routing['function']= '';/* * ------------------------------- * CUSTOM 习惯、定制的、自定义的 CONFIG VALUES * ------------------------------- * * The $assign_to_config array below will be passed 通过 dynamically to the * config class when initialized.初始化 This allows you to set custom config * items or override any default config values found in the config.php file. * This can be handy 方便的 as it permits 许可 you to share one application between * multiple front controller files, with each 每各 file containing 包含 different * config values. * * Un-comment the $assign_to_config array below to use this feature * */// $assign_to_config['name_of_config_item'] = 'value of config item';// --------------------------------// END OF USER CONFIGURABLE 可配置的 SETTINGS. DO NOT EDIT BELOW THIS LINE// end of 最终 user configurable settings . do not edit below this line// --------------------------------/* * --------------------------- * Resolve 决定 the system path for increased 增强的、增加 reliability 可靠性 * --------------------------- */// Set the current directory correctly 正确的 for CLI requests 请求if (defined('STDIN')){chdir(dirname(__FILE__));}if (realpath($system_path) !== FALSE){$system_path = realpath($system_path).'/';}// ensure 保证 there's a trailing 后面的 slash 斜杠$system_path = rtrim($system_path, '/').'/';// Is the system path correct?if ( ! is_dir($system_path)){exit("Your system folder path does not appear to be set correctly. Please open the following file and correct this: ".pathinfo(__FILE__, PATHINFO_BASENAME));}/* * ------------------------------- * Now that we know the path, set the main path constants 常量 * ------------------------------- */// The name of THIS filedefine('SELF', pathinfo(__FILE__, PATHINFO_BASENAME));// The PHP file extension 扩展// this global constant is deprecated.不赞成 弃用define('EXT', '.php');// Path to the system folderdefine('BASEPATH', str_replace("\\", "/", $system_path));// Path to the front controller （front controller）前端控制器 (this file)define('FCPATH', str_replace(SELF, '', __FILE__));// Name of the "system folder"define('SYSDIR', trim(strrchr(trim(BASEPATH, '/'), '/'), '/'));// The path to the "application" folderif (is_dir($application_folder)){define('APPPATH', $application_folder.'/');}else{if ( ! is_dir(BASEPATH.$application_folder.'/')){exit("Your application folder path does not appear to be set correctly. Please open the following file and correct this: ".SELF);}define('APPPATH', BASEPATH.$application_folder.'/');}/* * -------------------------------- * LOAD THE BOOTSTRAP 引导程序 FILE * -------------------------------- * * And away we go... 和我们走 * */require_once BASEPATH.'core/CodeIgniter.php';/* End of file index.php *//* Location: ./index.php */