当前位置:Gxlcms > PHP教程 > CI加载流程小结

CI加载流程小结

时间:2021-07-01 10:21:17 帮助过:30人阅读

  无聊,决定水一把。

  CI(CodeIgniter)是我最早接触的一个框架,到现在也只是用了其中一点零碎的方法。一直想对其流程做个小结,却总是因各种各样的“理由”挨着。看见别人图表齐上阵,没那耐心,就从代码说起吧,权当做个笔记,纪念一下。

  看在线的用户手册,也知道,将CI下载下来(最新版本2.2.1),解压到机子上,比如www目录,可改个根目录名(原名CodeIgniter-2.2-stable太长),初步目录文件如下,当然这在是windows下面。

  

访问下,如localhost/ci/index.php,就进入CI默认的Welcome页面

  

  如何一步步加载这个页面的?首先访问的是index.php脚本

  1 php
  2 
  3 /*
  4  *---------------------------------------------------------------
  5  * APPLICATION ENVIRONMENT
  6  *---------------------------------------------------------------
  7  *
  8  * You can load different configurations depending on your
  9  * current environment. Setting the environment also influences
 10  * things like logging and error reporting.
 11  *
 12  * This can be set to anything, but default usage is:
 13  *
 14  *     development
 15  *     testing
 16  *     production
 17  *
 18  * NOTE: If you change these, also change the error_reporting() code below
 19  *
 20  */
 21     define('ENVIRONMENT', 'development');
 22 /*
 23  *---------------------------------------------------------------
 24  * ERROR REPORTING
 25  *---------------------------------------------------------------
 26  *
 27  * Different environments will require different levels of error reporting.
 28  * By default development will show errors but testing and live will hide them.
 29  */
 30 
 31 if (defined('ENVIRONMENT'))
 32 {
 33     switch (ENVIRONMENT)
 34     {
 35         case 'development':
 36             error_reporting(E_ALL);
 37         break;
 38 
 39         case 'testing':
 40         case 'production':
 41             error_reporting(0);
 42         break;
 43 
 44         default:
 45             exit('The application environment is not set correctly.');
 46     }
 47 }
 48 
 49 /*
 50  *---------------------------------------------------------------
 51  * SYSTEM FOLDER NAME
 52  *---------------------------------------------------------------
 53  *
 54  * This variable must contain the name of your "system" folder.
 55  * Include the path if the folder is not in the same  directory
 56  * as this file.
 57  *
 58  */
 59     $system_path = 'system';
 60 
 61 /*
 62  *---------------------------------------------------------------
 63  * APPLICATION FOLDER NAME
 64  *---------------------------------------------------------------
 65  *
 66  * If you want this front controller to use a different "application"
 67  * folder then the default one you can set its name here. The folder
 68  * can also be renamed or relocated anywhere on your server.  If
 69  * you do, use a full server path. For more info please see the user guide:
 70  * http://codeigniter.com/user_guide/general/managing_apps.html
 71  *
 72  * NO TRAILING SLASH!
 73  *
 74  */
 75     $application_folder = 'application';
 76 
 77 /*
 78  * --------------------------------------------------------------------
 79  * DEFAULT CONTROLLER
 80  * --------------------------------------------------------------------
 81  *
 82  * Normally you will set your default controller in the routes.php file.
 83  * You can, however, force a custom routing by hard-coding a
 84  * specific controller class/function here.  For most applications, you
 85  * WILL NOT set your routing here, but it's an option for those
 86  * special instances where you might want to override the standard
 87  * routing in a specific front controller that shares a common CI installation.
 88  *
 89  * IMPORTANT:  If you set the routing here, NO OTHER controller will be
 90  * callable. In essence, this preference limits your application to ONE
 91  * specific controller.  Leave the function name blank if you need
 92  * to call functions dynamically via the URI.
 93  *
 94  * Un-comment the $routing array below to use this feature
 95  *
 96  */
 97     // The directory name, relative to the "controllers" folder.  Leave blank
 98     // if your controller is not in a sub-folder within the "controllers" folder
 99     // $routing['directory'] = '';
100 
101     // The controller class file name.  Example:  Mycontroller
102     // $routing['controller'] = '';
103 
104     // The controller function you wish to be called.
105     // $routing['function']    = '';
106 
107 
108 /*
109  * -------------------------------------------------------------------
110  *  CUSTOM CONFIG VALUES
111  * -------------------------------------------------------------------
112  *
113  * The $assign_to_config array below will be passed dynamically to the
114  * config class when initialized. This allows you to set custom config
115  * items or override any default config values found in the config.php file.
116  * This can be handy as it permits you to share one application between
117  * multiple front controller files, with each file containing different
118  * config values.
119  *
120  * Un-comment the $assign_to_config array below to use this feature
121  *
122  */
123     // $assign_to_config['name_of_config_item'] = 'value of config item';
124 
125 
126 
127 // --------------------------------------------------------------------
128 // END OF USER CONFIGURABLE SETTINGS.  DO NOT EDIT BELOW THIS LINE
129 // --------------------------------------------------------------------
130 
131 /*
132  * ---------------------------------------------------------------
133  *  Resolve the system path for increased reliability
134  * ---------------------------------------------------------------
135  */
136 
137     // Set the current directory correctly for CLI requests
138     if (defined('STDIN'))
139     {
140         chdir(dirname(__FILE__));
141     }
142 
143     if (realpath($system_path) !== FALSE)
144     {
145         $system_path = realpath($system_path).'/';
146     }
147 
148     // ensure there's a trailing slash
149     $system_path = rtrim($system_path, '/').'/';
150 
151     // Is the system path correct?
152     if ( ! is_dir($system_path))
153     {
154         exit("Your system folder path does not appear to be set correctly. Please open the following file and correct this: ".pathinfo(__FILE__, PATHINFO_BASENAME));
155     }
156 
157 /*
158  * -------------------------------------------------------------------
159  *  Now that we know the path, set the main path constants
160  * -------------------------------------------------------------------
161  */
162     // The name of THIS file
163     define('SELF', pathinfo(__FILE__, PATHINFO_BASENAME));
164 
165     // The PHP file extension
166     // this global constant is deprecated.
167     define('EXT', '.php');
168 
169     // Path to the system folder
170     define('BASEPATH', str_replace("\\", "/", $system_path));
171 
172     // Path to the front controller (this file)
173     define('FCPATH', str_replace(SELF, '', __FILE__));
174 
175     // Name of the "system folder"
176     define('SYSDIR', trim(strrchr(trim(BASEPATH, '/'), '/'), '/'));
177 
178 
179     // The path to the "application" folder
180     if (is_dir($application_folder))
181     {
182         define('APPPATH', $application_folder.'/');
183     }
184     else
185     {
186         if ( ! is_dir(BASEPATH.$application_folder.'/'))
187         {
188             exit("Your application folder path does not appear to be set correctly. Please open the following file and correct this: ".SELF);
189         }
190 
191         define('APPPATH', BASEPATH.$application_folder.'/');
192     }
193 
194 /*
195  * --------------------------------------------------------------------
196  * LOAD THE BOOTSTRAP FILE
197  * --------------------------------------------------------------------
198  *
199  * And away we go...
200  *
201  */
202 require_once BASEPATH.'core/CodeIgniter.php';
203 
204 /* End of file index.php */
205 /* Location: ./index.php */

View Code

  21行:首先定义一个ENVIRONMENT常量为development,即开发环境。

  31-47行:switch语句,由于当前环境是development,所以是设置报告所有级别的错误。

  49-59行:$system_path变量定义CI的默认的系统脚本目录是 system,61-75行定义当前默认的供我们主要开发用的目录为 application。

  77-105行:全部注释掉了,这里是我们可以强制设置系统加载时默认的目录名($routing['directory'])、控制器名($routing['directory'])和方法名($routing['directory']),虽然一般这些是设置在application\config\routes.php中(下图),访问的Welcome页面也是通过这个默认控制器Welcome类进行的,这里只是作为一个选择性的方式,其实没必要弄

  

  108-129行:全部注释掉,用于自定义配置变量(CUSTOM CONFIG VALUES),前一篇说过,任何后端project中,总有些配置信息,只是各个项目或框架加载方式不同,这个$assign_to_config数组就存放我们的自定义配置信息,如$assign_to_config['home'] = 'localhost'; ,之所以注释掉,又是因为这只是一个可选的操作,CI的用户自定义配置信息,一般放在application\config目录下边,以自动加载信息(autoload.php),普通配置信息(config.php)、常量(constants.php)、数据库(database.php)等分开文件存储,所以一般不会在这里的去配置一个要用到的变量,$assign_to_config默认是没有定义的。

  

   从131行到index.php文件末尾主要是对一些路径变量的定义。

  137-141行:是为CLI(Command-Interface Line)的调用方式准备的,是直接在Mac/Linux系统上通过终端命令运行脚本,这个在CI中文官网(http://codeigniter.org.cn/user_guide/general/cli.html)也有介绍,如果定义了名为STDIN的常量,则将执行目录改为当前文件所在目录,当然前面没有出现过STDIN这个常量的定义,这里就不会执行了。

  

  143-155行:确定框架存放系统脚本的目录变量$system_path,也就是前面图中的system目录,这里会检测它的有效性,无效的话程序就挂在这里了。

  157-192行:定义若干主要目录常量,分别是SELF:当前脚本的文件名、EXT:脚本扩展名、BASEPATH:system目录的路径、FCPATH:当前脚本所在的目录、SYSDIR:system目录的目录名,不改动的话就是system。

  179-194行:定义APPPATH常量,确定application所在的目录,就是以后我们主要开发的地方,使用is_dir检测,稍微注意的是is_dir可以检测相对目录,所以实际运行的是if里边的代码,APPPATH得到的是相对路径。

  最后打印看看这些变(常)量的值都是啥,有的与存放目录相关:

  

  202行:加载BASEPATH.'core/CodeIgniter.php'脚本,就是system目录下的核心类文件目录下的文件,进入到CI的核心类目录下的文件了。

=====================================================================================================

  1 if ( ! defined('BASEPATH')) exit('No direct script access allowed');
  2 /**
  3  * CodeIgniter
  4  *
  5  * An open source application development framework for PHP 5.1.6 or newer
  6  *
  7  * @package        CodeIgniter
  8  * @author        EllisLab Dev Team
  9  * @copyright        Copyright (c) 2008 - 2014, EllisLab, Inc.
 10  * @copyright        Copyright (c) 2014 - 2015, British Columbia Institute of Technology (http://bcit.ca/)
 11  * @license        http://codeigniter.com/user_guide/license.html
 12  * @link        http://codeigniter.com
 13  * @since        Version 1.0
 14  * @filesource
 15  */
 16 
 17 // ------------------------------------------------------------------------
 18 
 19 /**
 20  * System Initialization File
 21  *
 22  * Loads the base classes and executes the request.
 23  *
 24  * @package        CodeIgniter
 25  * @subpackage    codeigniter
 26  * @category    Front-controller
 27  * @author        EllisLab Dev Team
 28  * @link        http://codeigniter.com/user_guide/
 29  */
 30 
 31 /**
 32  * CodeIgniter Version
 33  *
 34  * @var string
 35  *
 36  */
 37     define('CI_VERSION', '2.2.1');
 38 
 39 /**
 40  * CodeIgniter Branch (Core = TRUE, Reactor = FALSE)
 41  *
 42  * @var boolean
 43  *
 44  */
 45     define('CI_CORE', FALSE);
 46 
 47 /*
 48  * ------------------------------------------------------
 49  *  Load the global functions
 50  * ------------------------------------------------------
 51  */
 52     require(BASEPATH.'core/Common.php');
 53 
 54 /*
 55  * ------------------------------------------------------
 56  *  Load the framework constants
 57  * ------------------------------------------------------
 58  */
 59     if (defined('ENVIRONMENT') AND file_exists(APPPATH.'config/'.ENVIRONMENT.'/constants.php'))
 60     {
 61         require(APPPATH.'config/'.ENVIRONMENT.'/constants.php');
 62     }
 63     else
 64     {
 65         require(APPPATH.'config/constants.php');
 66     }
 67 
 68 /*
 69  * ------------------------------------------------------
 70  *  Define a custom error handler so we can log PHP errors
 71  * ------------------------------------------------------
 72  */
 73     set_error_handler('_exception_handler');
 74 
 75     if ( ! is_php('5.3'))
 76     {
 77         @set_magic_quotes_runtime(0); // Kill magic quotes
 78     }
 79 
 80 /*
 81  * ------------------------------------------------------
 82  *  Set the subclass_prefix
 83  * ------------------------------------------------------
 84  *
 85  * Normally the "subclass_prefix" is set in the config file.
 86  * The subclass prefix allows CI to know if a core class is
 87  * being extended via a library in the local application
 88  * "libraries" folder. Since CI allows config items to be
 89  * overriden via data set in the main index. php file,
 90  * before proceeding we need to know if a subclass_prefix
 91  * override exists.  If so, we will set this value now,
 92  * before any classes are loaded
 93  * Note: Since the config file data is cached it doesn't
 94  * hurt to load it here.
 95  */
 96     if (isset($assign_to_config['subclass_prefix']) AND $assign_to_config['subclass_prefix'] != '')
 97     {
 98         get_config(array('subclass_prefix' => $assign_to_config['subclass_prefix']));
 99     }
100 
101 /*
102  * ------------------------------------------------------
103  *  Set a liberal script execution time limit
104  * ------------------------------------------------------
105  */
106     if (function_exists("set_time_limit") == TRUE AND @ini_get("safe_mode") == 0)
107     {
108         @set_time_limit(300);
109     }
110 
111 /*
112  * ------------------------------------------------------
113  *  Start the timer... tick tock tick tock...
114  * ------------------------------------------------------
115  */
116     $BM =& load_class('Benchmark', 'core');
117     $BM->mark('total_execution_time_start');
118     $BM->mark('loading_time:_base_classes_start');
119 
120 /*
121  * ------------------------------------------------------
122  *  Instantiate the hooks class
123  * ------------------------------------------------------
124  */
125     $EXT =& load_class('Hooks', 'core');
126 
127 /*
128  * ------------------------------------------------------
129  *  Is there a "pre_system" hook?
130  * ------------------------------------------------------
131  */
132     $EXT->_call_hook('pre_system');
133 
134 /*
135  * ------------------------------------------------------
136  *  Instantiate the config class
137  * ------------------------------------------------------
138  */
139     $CFG =& load_class('Config', 'core');
140 
141     // Do we have any manually set config items in the index.php file?
142     if (isset($assign_to_config))
143     {
144         $CFG->_assign_to_config($assign_to_config);
145     }
146 
147 /*
148  * ------------------------------------------------------
149  *  Instantiate the UTF-8 class
150  * ------------------------------------------------------
151  *
152  * Note: Order here is rather important as the UTF-8
153  * class needs to be used very early on, but it cannot
154  * properly determine if UTf-8 can be supported until
155  * after the Config class is instantiated.
156  *
157  */
158 
159     $UNI =& load_class('Utf8', 'core');
160 
161 /*
162  * ------------------------------------------------------
163  *  Instantiate the URI class
164  * ------------------------------------------------------
165  */
166     $URI =& load_class('URI', 'core');
167 
168 /*
169  * ------------------------------------------------------
170  *  Instantiate the routing class and set the routing
171  * ------------------------------------------------------
172  */
173     $RTR =& load_class('Router', 'core');
174     $RTR->_set_routing();
175 
176     // Set any routing overrides that may exist in the main index file
177     if (isset($routing))
178     {
179         $RTR->_set_overrides($routing);
180     }
181 
182 /*
183  * ------------------------------------------------------
184  *  Instantiate the output class
185  * ------------------------------------------------------
186  */
187     $OUT =& load_class('Output', 'core');
188 
189 /*
190  * ------------------------------------------------------
191  *    Is there a valid cache file?  If so, we're done...
192  * ------------------------------------------------------
193  */
194     if ($EXT->_call_hook('cache_override') === FALSE)
195     {
196         if ($OUT->_display_cache($CFG, $URI) == TRUE)
197         {
198             exit;
199         }
200     }
201 
202 /*
203  * -----------------------------------------------------
204  * Load the security class for xss and csrf support
205  * -----------------------------------------------------
206  */
207     $SEC =& load_class('Security', 'core');
208 
209 /*
210  * ------------------------------------------------------
211  *  Load the Input class and sanitize globals
212  * ------------------------------------------------------
213  */
214     $IN    =& load_class('Input', 'core');
215 
216 /*
217  * ------------------------------------------------------
218  *  Load the Language class
219  * ------------------------------------------------------
220  */
221     $LANG =& load_class('Lang', 'core');
222 
223 /*
224  * ------------------------------------------------------
225  *  Load the app controller and local controller
226  * ------------------------------------------------------
227  *
228  */
229     // Load the base controller class
230     require BASEPATH.'core/Controller.php';
231 
232     function &get_instance()
233     {
234         return CI_Controller::get_instance();
235     }
236 
237 
238     if (file_exists(APPPATH.'core/'.$CFG->config['subclass_prefix'].'Controller.php'))
239     {
240         require APPPATH.'core/'.$CFG->config['subclass_prefix'].'Controller.php';
241     }
242 
243     // Load the local application controller
244     // Note: The Router class automatically validates the controller path using the router->_validate_request().
245     // If this include fails it means that the default controller in the Routes.php file is not resolving to something valid.
246     if ( ! file_exists(APPPATH.'controllers/'.$RTR->fetch_directory().$RTR->fetch_class().'.php'))
247     {
248         show_error('Unable to load your default controller. Please make sure the controller specified in your Routes.php file is valid.');
249     }
250 
251     include(APPPATH.'controllers/'.$RTR->fetch_directory().$RTR->fetch_class().'.php');
252 
253     // Set a mark point for benchmarking
254     $BM->mark('loading_time:_base_classes_end');
255 
256 /*
257  * ------------------------------------------------------
258  *  Security check
259  * ------------------------------------------------------
260  *
261  *  None of the functions in the app controller or the
262  *  loader class can be called via the URI, nor can
263  *  controller functions that begin with an underscore
264  */
265     $class  = $RTR->fetch_class();
266     $method = $RTR->fetch_method();
267 
268     if ( ! class_exists($class)
269         OR strncmp($method, '_', 1) == 0
270         OR in_array(strtolower($method), array_map('strtolower', get_class_methods('CI_Controller')))
271         )
272     {
273         if ( ! empty($RTR->routes['404_override']))
274         {
275             $x = explode('/', $RTR->routes['404_override']);
276             $class = $x[0];
277             $method = (isset($x[1]) ? $x[1] : 'index');
278             if ( ! class_exists($class))
279             {
280                 if ( ! file_exists(APPPATH.'controllers/'.$class.'.php'))
281                 {
282                     show_404("{$class}/{$method}");
283                 }
284 
285                 include_once(APPPATH.'controllers/'.$class.'.php');
286             }
287         }
288         else
289         {
290             show_404("{$class}/{$method}");
291         }
292     }
293 
294 /*
295  * ------------------------------------------------------
296  *  Is there a "pre_controller" hook?
297  * ------------------------------------------------------
298  */
299     $EXT->_call_hook('pre_controller');
300 
301 /*
302  * ------------------------------------------------------
303  *  Instantiate the requested controller
304  * ------------------------------------------------------
305  */
306     // Mark a start point so we can benchmark the controller
307     $BM->mark('controller_execution_time_( '.$class.' / '.$method.' )_start');
308 
309     $CI = new $class();
310 
311 /*
312  * ------------------------------------------------------
313  *  Is there a "post_controller_constructor" hook?
314  * ------------------------------------------------------
315  */
316     $EXT->_call_hook('post_controller_constructor');
317 
318 /*
319  * ------------------------------------------------------
320  *  Call the requested method
321  * ------------------------------------------------------
322  */
323     // Is there a "remap" function? If so, we call it instead
324     if (method_exists($CI, '_remap'))
325     {
326         $CI->_remap($method, array_slice($URI->rsegments, 2));
327     }
328     else
329     {
330         // is_callable() returns TRUE on some versions of PHP 5 for private and protected
331         // methods, so we'll use this workaround for consistent behavior
332         if ( ! in_array(strtolower($method), array_map('strtolower', get_class_methods($CI))))
333         {
334             // Check and see if we are using a 404 override and use it.
335             if ( ! empty($RTR->routes['404_override']))
336             {
337                 $x = explode('/', $RTR->routes['404_override']);
338                 $class = $x[0];
339                 $method = (isset($x[1]) ? $x[1] : 'index');
340                 if ( ! class_exists($class))
341                 {
342                     if ( ! file_exists(APPPATH.'controllers/'.$class.'.php'))
343                     {
344                         show_404("{$class}/{$method}");
345                     }
346 
347                     include_once(APPPATH.'controllers/'.$class.'.php');
348                     unset($CI);
349                     $CI = new $class();
350                 }
351             }
352             else
353             {
354                 show_404("{$class}/{$method}");
355             }
356         }
357 
358         // Call the requested method.
359         // Any URI segments present (besides the class/function) will be passed to the method for convenience
360         call_user_func_array(array(&$CI, $method), array_slice($URI->rsegments, 2));
361     }
362 
363 
364     // Mark a benchmark end point
365     $BM->mark('controller_execution_time_( '.$class.' / '.$method.' )_end');
366 
367 /*
368  * ------------------------------------------------------
369  *  Is there a "post_controller" hook?
370  * ------------------------------------------------------
371  */
372     $EXT->_call_hook('post_controller');
373 
374 /*
375  * ------------------------------------------------------
376  *  Send the final rendered output to the browser
377  * ------------------------------------------------------
378  */
379     if ($EXT->_call_hook('display_override') === FALSE)
380     {
381         $OUT->_display();
382     }
383 
384 /*
385  * ------------------------------------------------------
386  *  Is there a "post_system" hook?
387  * ------------------------------------------------------
388  */
389     $EXT->_call_hook('post_system');
390 
391 /*
392  * ------------------------------------------------------
393  *  Close the DB connection if one exists
394  * ------------------------------------------------------
395  */
396     if (class_exists('CI_DB') AND isset($CI->db))
397     {
398         $CI->db->close();
399     }
400 
401 
402 /* End of file CodeIgniter.php */
403 /* Location: ./system/core/CodeIgniter.php */

View Code

  在CodeIgniter中,可以看到开头的英文描述,该脚本时系统初始化文件,主要作用是装载基类和执行请求。

  31-45行:定义了CI_VERSION常量,描述当前框架版本,CI_CORE常量,目前我也不清楚没探究过,注释是CI的分支,啥意思?

  52行:加载系统核心目录下的Common.php文件,Load the global functions,记得前一篇中说到,一般一个项目会将很多公共方法放在一个脚本中加载进来,通常取名Utilities.php,也可是Common.php,这里的Common.php也是这个意思,如它的解释是“加载全局函数”,即这里的函数都是后边直接拿来用的。在这个脚本中有两个重要的方法(目前来说)一个是get_config,单独拿出来如下

 1 php
 2 /**
 3 * Loads the main config.php file
 4 *
 5 * This function lets us grab the config file even if the Config class
 6 * hasn't been instantiated yet
 7 *
 8 * @access    private
 9 * @return    array
10 */
11 if ( ! function_exists('get_config'))
12 {
13     function &get_config($replace = array())
14     {
15         static $_config;
16 
17         if (isset($_config))
18         {
19             return $_config[0];
20         }
21 
22         // Is the config file in the environment folder?
23         if ( ! defined('ENVIRONMENT') OR ! file_exists($file_path = APPPATH.'config/'.ENVIRONMENT.'/config.php'))
24         {
25             $file_path = APPPATH.'config/config.php';
26         }
27 
28         // Fetch the config file
29         if ( ! file_exists($file_path))
30         {
31             exit('The configuration file does not exist.');
32         }
33 
34         require($file_path);
35 
36         // Does the $config array exist in the file?
37         if ( ! isset($config) OR ! is_array($config))
38         {
39             exit('Your config file does not appear to be formatted correctly.');
40         }
41 
42         // Are any values being dynamically replaced?
43         if (count($replace) > 0)
44         {
45             foreach ($replace as $key => $val)
46             {
47                 if (isset($config[$key]))
48                 {
49                     $config[$key] = $val;
50                 }
51             }
52         }
53 
54         $_config[0] =& $config;
55         return $_config[0];
56     }
57 }

View Code

  注释说它加载主要的config.php文件,它使得我们能抓取到配置文件,即便配置类还未被实例化。在CI中,有专门的核心配置类CI_Config来加载配置信息,而这里的get_config方法也能获得主要配置信息,注意是主要配置信息,在application/config目录下有很多其他的配置信息文件(前面在自定义配置变量时也说过CI将配置信息分为了很多文件),其中有一个config.php文件就是get_config能获取到的,这个文件存放的就是基本信息,如果你还想获取其他的配置信息,貌似就要用配置类了。所以如果想添加节本配置信息就在这个里边。

  如果是第一次调用get_config方法,先声明静态变量$_config,如果已定义则直接返回它的索引为0的子数组。然后查看APPPATH/config/ENVIRONMENT/config.php文件是否存在(前面打印已知ENVIRONMENT常量值,未改动就是development,原始的框架中没有这个目录,所以这里加载的是application/config/config.php(只加载了这一个,其他的配置文件没有),可以打开看看config.php中定义了一个$config数组,一些基本定义如基础链接、链接后缀、编码、语言、缓存、日志、钩子等等。如果传入一个关联数组,它会将键-值(临时)加入$_config中。总之,get_config方法主要得到的是config.php中定义的数组变量。

  与get_config相关的config_item方法则是得到这个数组变量中的某一项。

  另一个比较重要的方法是load_class:

 1 php
 2 /**
 3 * Class registry
 4 *
 5 * This function acts as a singleton.  If the requested class does not
 6 * exist it is instantiated and set to a static variable.  If it has
 7 * previously been instantiated the variable is returned.
 8 *
 9 * @access    public
10 * @param    string    the class name being requested
11 * @param    string    the directory where the class should be found
12 * @param    string    the class name prefix
13 * @return    object
14 */
15 if ( ! function_exists('load_class'))
16 {
17     function &load_class($class, $directory = 'libraries', $prefix = 'CI_')
18     {
19         static $_classes = array();
20 
21         // Does the class exist?  If so, we're done...
22         if (isset($_classes[$class]))
23         {
24             return $_classes[$class];
25         }
26 
27         $name = FALSE;
28 
29         // Look for the class first in the local application/libraries folder
30         // then in the native system/libraries folder
31         foreach (array(APPPATH, BASEPATH) as $path)
32         {
33             if (file_exists($path.$directory.'/'.$class.'.php'))
34             {
35                 $name = $prefix.$class;
36 
37                 if (class_exists($name) === FALSE)
38                 {
39                     require($path.$directory.'/'.$class.'.php');
40                 }
41 
42                 break;
43             }
44         }
45 
46         // Is the request a class extension?  If so we load it too
47         if (file_exists(APPPATH.$directory.'/'.config_item('subclass_prefix').$class.'.php'))
48         {
49             $name = config_item('subclass_prefix').$class;
50 
51             if (class_exists($name) === FALSE)
52             {
53                 require(APPPATH.$directory.'/'.config_item('subclass_prefix').$class.'.php');
54             }
55         }
56 
57         // Did we find the class?
58         if ($name === FALSE)
59         {
60             // Note: We use exit() rather then show_error() in order to avoid a
61             // self-referencing loop with the Excptions class
62             exit('Unable to locate the specified class: '.$class.'.php');
63         }
64 
65         // Keep track of what we just loaded
66         is_loaded($class);
67 
68         $_classes[$class] = new $name();
69         return $_classes[$class];
70     }
71 }

View Code

  先看它的注释:这个方法作为一个单例,如果被请求的类没有出现过,则该类会被实例化为一个static variable,如果先前被实例化过则直接返回它。它的三个参数分别是请求的类名、所在目录,类名前缀。可以看到,目录默认是libraries,在application和system中均有它,它就是存放我们自定义的类库或者CI自带的类库的地方,就是自定义工具和CI提供的工具,如日历类、加密类、Ftp类、日志类、Session会话类、Email邮件收发类、JavaScript类、ZIP压缩类等等。或许你已经注意到这里返回的是引用而非值,就像它将加载的类作为静态变量一样,这些细节地方最终提高了整个系统的访问速度。

  大致流程:先定义一个静态数组,若数组中已有该类直接返回。先后扫描APPPATH和BASEPATH(前面已知这俩常量值)文件夹下的$directory(默认值是libraries)目录下的$class.php文件是否存在,存在则加上CI的标准类前缀CI_(第三个参数的默认值),在检查类存在与否,存在则require该文件(从这里可知,class_exists()在判断类是否存在时并不需要先加载该类文件),一旦文件出现则加载它,并break跳出。注意扫描顺序,先APPPATH后BASEPATH,假如只传第一个参数类名,则优先在我们自己开发的application目录libraries中寻找,然后才去system目录的libraries下边。

  由于我们可以对CI的核心类进行扩展(继承它们),所以在扫描完APPPATH和BASEPATH的核心类(名称以CI_为前缀)目录后,还要扫描APPPATH的libraries下边是否有自定义的扩展类(默认以MY_为前缀),有的话也要加载它们,然后实例化一个对应对象(有扩展类是扩展类)存入$_classes静态数组并返回该对象。

  对Common.php有大致了解后回到CodeIgniter.php脚本。

  54-66行:加载APPPATH.'config/constants.php'脚本,constants.php如同名字一样放的是framework constants,集中定义了一些常量,所以我们在添加常量时就可以放到这里边来定义。

  

  68-78行:首先定义了一个自定义错误处理方法_exception_handler。判断php版本,非5.3关闭magic_quotes引用,这个配置在5.3版本已弃用,提高安全性。

  80-99行:这里就是将前面说过的$assign_to_config自定义配置信息数组临时加到$_config数组中,通过get_config方法实现,前面说过$assign_to_config默认是没有定义的,这里的if语句也不会运行。

  101-109行:设置自定义脚本最大执行时间为300秒(略长,跑日志的话得更长)

  111-118行:加载核心类Benchmark,设置两个标记点。Benchmark基准测试类,就是测试某个开始标记到结束标记之间占用的内存大小、执行时间等信息,测试嘛,当然它要结合CI中一个叫分析器的东西使用。

  120-132行:加载核心类Hooks,钩子,设置了一个系统开始执行的钩子(实际未执行,因为application/config/config.php关于它的配置信息默认设置为false,即不启用钩子)。它就就相当于一个触发器,在某个东西要执行前开始执行某些代码,比如控制器加载前、加载后等,一旦控制器加载就运行指定的代码。在这里,它尝试调用一个pre_system(系统执行前)的扩展,默认不执行。

  134-145行:加载核心类Config,配置类,它用来加载其他需需要的配置信息,并且它再次加载$assign_to_config数组中配置信息如果该数组定义了的话。

  147-159行:加载核心类Utf8,编码类。

  161-166行:加载核心类URI,路由。

  168-180行:加载核心类Router,路径处理类,_set_routing方法设置好访问路径。如果路径配置数组$routing(前面提到默认是注释掉的)定义了的话,将覆盖默认的路由配置。如果你输入了不存在的脚本路径,在这一步就停住,开始报404了,当然还得Router里边的方法处理。

  Router类里面,URI作为它的一个成员存在,实际处理方法在URI类中,熟悉点的都知道CI的访问方式默认是段(segment)的形式,据说更有利于搜索引擎。一个简单的访问方式是这样的localhost/ci/index.php/Controller/Function/Arguments,它们将访问的形式解析为需要的控制器,调用的方法,以及提供的参数列表,当然也可启用传统的查询字符串形式。具体方法略复杂。

  187行:加载核心类Output。

  189-200行:通过Hooks类和Output类检测有无缓存,有的话直接输出缓存页面,跳出脚本了。这也是在CI的介绍中应用程序流程图部分,当路径处理完后,若有缓存直接输出的原因。

  

  207行:加载核心类Security。

  214行:加载核心类Input。

  221行:加载核心类Lang,语言处理。

  229-235行:加载核心类Controller,它是所有控制器的基类,而get_instance全局方法也能得到它的实例,Controller的牛逼之处在于,它将前面所有通过load_calss载入的libraries(默认)目录(APPPATH和BASEPATH)中的工具库全部实例化为对象,并作为它的属性成员。所以这里的get_instance方法得到的实例也被CI称为超对象(好像是这个名字),因为通过这个对象就可以获取所有通过前面加载的对象实例。

  238-242行:加载自定义的,对上一步的核心类CI_Controller的扩展类的文件,默认就是MY_Controller,当然前提是如果你扩展了的的话。

  243-251行:通过核心类Router的实例,提取当前访问的控制器所在的目录和类名,不存在则报错,存在则加载它,这里就加载了默认的welcome控制器文件。当然如果你自己定义了控制器类文件并访问,也是在这里被include进来的(通过Router类提取子目录$RTR->fetch_directory(),若存在,提取类名$RTR->fetch_class()来找),大概在246行的if语句块,就是检查这个类文件是否存在。

  252行:设置一个基准测试结束标记,标记加载基本核心类结束(这些测试默认不会执行)。

  256-292行:安全检查。先通过Router类取得类名和要执行的方法名,if条件检查3项内容。1. 上面的243-251行是找到了控制器对应的脚本,并且加载了它,但是假如这只是一个名字匹配的空脚本呢?里边什么都没写就不行了,于是要检查类的定义是否存在(class_exists),2. 以下划线_开头的方法名不能执行,直接报错,当然这是CI自己的的规则,也就是说无论你的类定义的以_开头的方法即使是公有访问属性也不行(除了一个_remap),3. 当类中的方法根控制器核心类中的方法同名时也不行。定义方法名时有个印象就行了。进入if中就很可能会404了。

  298行:Hooks类尝试调用一个pre_controller(控制器执行前)的扩展,默认没有。

  301-309行:基准测试类设置一个起点标记,目的在于测试控制器执行的时长(默认不显示测试信息),并且实例化前面加载的控制器类,默认的就是Welcome。

  315行:Hooks尝试执行post_controller_constructor(所调用的控制器类构造完成后)的扩展,默认没有。

  317-364行:开始调用指定的控制器类的指定方法(当然这里是默认控制器Welcome的默认方法index)。看看这个流程,首先一个if判断,如果你的控制器类中有方法_remap,只调用它了,所以前面说以下划线开头的方法除了_remap,这也是CI的一个类的方法的规则,有了这个重映射方法,只调它。默认的Welcome

人气教程排行