CodeIgniter源码分析（二） 入口文件index.php

 1 <?php
 2
 3 /* 设定环境 */
 4 define(‘ENVIRONMENT‘, ‘development‘);
 5
 6 if (defined(‘ENVIRONMENT‘))
 7 {
 8     switch (ENVIRONMENT)
 9     {
10         case ‘development‘:
11             error_reporting(E_ALL);
12         break;
13
14         case ‘testing‘:
15         case ‘production‘:
16             error_reporting(0);
17         break;
18
19         default:
20             exit(‘The application environment is not set correctly.‘);
21     }
22 }
23
24 /* 系统文件夹名 */
25 $system_path = ‘system‘;
26
27 /* 应用文件夹名 */
28 $application_folder = ‘application‘;
29
30 // 把当前的目录改变为指定的目录
31 if (defined(‘STDIN‘))
32 {
33     chdir(dirname(__FILE__));
34 }
35
36 if (realpath($system_path) !== FALSE)        //返回绝对路径
37 {
38     $system_path = realpath($system_path).‘/‘;
39 }
40
41 // 系统路径
42 $system_path = rtrim($system_path, ‘/‘).‘/‘;
43
44
45 if ( ! is_dir($system_path))
46 {
47     exit("系统文件路径设置错误");
48 }
49     //当前文件的名字
50     define(‘SELF‘, pathinfo(__FILE__, PATHINFO_BASENAME));
51
52     //文件扩展名
53     define(‘EXT‘, ‘.php‘);
54
55     // Path to the system folder
56     define(‘BASEPATH‘, str_replace("\\", "/", $system_path));
57
58     // Path to the front controller (this file)
59     define(‘FCPATH‘, str_replace(SELF, ‘‘, __FILE__));
60
61     // Name of the "system folder"
62     define(‘SYSDIR‘, trim(strrchr(trim(BASEPATH, ‘/‘), ‘/‘), ‘/‘));
63
64     // The path to the "application" folder
65     if (is_dir($application_folder))
66     {
67         define(‘APPPATH‘, $application_folder.‘/‘);
68     }
69     else
70     {
71         if ( ! is_dir(BASEPATH.$application_folder.‘/‘))
72         {
73             exit("应用文件夹设置错误");
74         }
75
76         define(‘APPPATH‘, BASEPATH.$application_folder.‘/‘);
77     }
78
79 /*
80  * --------------------------------------------------------------------
81  * LOAD THE BOOTSTRAP FILE
82  * --------------------------------------------------------------------
83  *
84  * And away we go...
85  *
86  */
87 require_once BASEPATH.‘core/CodeIgniter.php‘;
88
89 /* End of file index.php */
90 /* Location: ./index.php */

该文件主要是设置项目运行环境

设置系统系统目录

设置部分常量：SELF、EXT、BASEPATH...