CodeIgniter框架源码学习之配置类－－Config.php

文件位置：./system/core/Config.php

1.成员属性$config 所有已加载配置的值的列表

2.成员属性$is_loaded 所有加载配置文件的列表

3.成员属性$_config_paths 当需要加载配置文件的时候搜索路径的列表

4.__construct() 构造方法程序会首先自动执行这个方法

它所做的内容主要有两个  a)获取配置赋值给成员属性$config

b)设置配置中的base_url

5.load($file = '', $use_sections = FALSE, $fail_gracefully = FALSE)

加载配置文件

$file 是你自定义的配置文件的文件名，这个文件名没有 .php 的扩展名. 

$use_sections  如果你需要加载多个自定义配置文件，一般情况下它们会被合并成一个数组。然而，如果在不同的配置文件中存在同名的索引，那么会发生冲突。为了避免这个问题，你可以把第二个参数设置为 TRUE ，这可以使每个配置文件的内容存储在一个单独的数组中，数组的索引就是配置文件的文件名。

$fail_gracefully允许屏蔽当配置文件不存在时产生的错误信息:

(0)过滤并设置$file 变量

(1)初始化$founf 为FALSE 用于判断文件是否存在

(2)初始化$loaded为FALSE 用于判断文件是否被加载

(3)检测文件路径如果有环境变量添加环境变量

(4)进入foreach遍历文件路径，并查找文件是否被加载和存在

(5)如果文件不存在跳出foreach循环

(6)加载文件

(7)判断$config是否存在，这个$config 应该是加载的文件中定义的

(8)判断$use_sections 如果为真则将使每个配置文件的内容存储在一个单独的数组中，数组的索引就是配置文件的文件名。

  如果为假则所有配置文件会被合并成一个数组

(9)将文件添加进is_loaded数组中，并销毁$config

(10)$loaded 设置为true log记录 跳出循环

(11)如果loaded为false并且$fail_gracefully不等于true 显示错误日志

6.item() 获取一个配置项

$item 配置项的名字

$index  如果配置是一个数组的时候，这一项是数组索引名字

(1)判断index是否为空

(2)如果index为空，判断$this->config[$item]是否存在，如果不存在返回，存在，赋值给$pref

(3)如果index不为空，判断$this->config[$index]是否存在，判断$this->config[$index][$item]是否存在，将$this->config[$index][$item]赋值给$pref

(4)返回$pref

7.slash_item() 获取一个配置项并添加/

$item 配置项的名字

(1)判断配置项是否存在不存在返回false

(2)判断配置项是否为空如果是空返回''

(3)在配置值的后面添加/并返回。

8.site_url() 该函数得到你网站的 URL，其中包含了你在 config 文件中设置的 "index" 的值。

$uri uri字符串就是访问路径所带的参数

(1) 如果$uri = '' 返回由base_url和index_page组成的url

(2) 判断$this->item('enable_query_strings')真假，并返回不同形式的地址。(这一项是在application/config/config.php文件中配置的。用来区分传参方式，如果为false就是默认的传参方式example.com/who/what/where/。如果为true就是 example.com/index.php?c=controller&m=function这样的传参方式。)

9.base_url() 该函数返回站点的根 URL，可以在这个函数后拼接一个 URL 路径，用以生成 CSS 或图片文件的 URL。

10._uri_string() 构建uri串让site_url()，base_url()两个函数使用。

11.system_url() 该函数得到 system 文件夹的 URL。

12.set_item()  设置一个配置项

贴上代码：

<?php
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP
 *
 * This content is released under the MIT License (MIT)
 *
 * Copyright (c) 2014 - 2017, British Columbia Institute of Technology
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * @package	CodeIgniter
 * @author	EllisLab Dev Team
 * @copyright	Copyright (c) 2008 - 2014, EllisLab, Inc. (https://ellislab.com/)
 * @copyright	Copyright (c) 2014 - 2017, British Columbia Institute of Technology (http://bcit.ca/)
 * @license	http://opensource.org/licenses/MIT	MIT License
 * @link	https://codeigniter.com
 * @since	Version 1.0.0
 * @filesource
 */
defined('BASEPATH') OR exit('No direct script access allowed');

/**
 * Config Class
 *
 * This class contains functions that enable config files to be managed
 *
 * @package		CodeIgniter
 * @subpackage	Libraries
 * @category	Libraries
 * @author		EllisLab Dev Team
 * @link		https://codeigniter.com/user_guide/libraries/config.html
 */
class CI_Config {

	/**
	 * List of all loaded config values
	 *
	 * @var	array
	 */
	public $config = array();

	/**
	 * List of all loaded config files
	 *
	 * @var	array
	 */
	public $is_loaded =	array();

	/**
	 * List of paths to search when trying to load a config file.
	 *
	 * @used-by	CI_Loader
	 * @var		array
	 */
	public $_config_paths =	array(APPPATH);

	// --------------------------------------------------------------------

	/**
	 * Class constructor
	 *
	 * Sets the $config data from the primary config.php file as a class variable.
	 *
	 * @return	void
	 */
	public function __construct()
	{
		$this->config =& get_config();

		// Set the base_url automatically if none was provided
		if (empty($this->config['base_url']))
		{
			if (isset($_SERVER['SERVER_ADDR']))
			{
				if (strpos($_SERVER['SERVER_ADDR'], ':') !== FALSE)
				{
					$server_addr = '['.$_SERVER['SERVER_ADDR'].']';
				}
				else
				{
					$server_addr = $_SERVER['SERVER_ADDR'];
				}

				$base_url = (is_https() ? 'https' : 'http').'://'.$server_addr
					.substr($_SERVER['SCRIPT_NAME'], 0, strpos($_SERVER['SCRIPT_NAME'], basename($_SERVER['SCRIPT_FILENAME'])));
			}
			else
			{
				$base_url = 'http://localhost/';
			}

			$this->set_item('base_url', $base_url);
		}

		log_message('info', 'Config Class Initialized');
	}

	// --------------------------------------------------------------------

	/**
	 * Load Config File
	 *
	 * @param	string	$file			Configuration file name
	 * @param	bool	$use_sections		Whether configuration values should be loaded into their own section
	 * @param	bool	$fail_gracefully	Whether to just return FALSE or display an error message
	 * @return	bool	TRUE if the file was loaded correctly or FALSE on failure
	 */
	public function load($file = '', $use_sections = FALSE, $fail_gracefully = FALSE)
	{
		$file = ($file === '') ? 'config' : str_replace('.php', '', $file);
		$loaded = FALSE;

		foreach ($this->_config_paths as $path)
		{
			foreach (array($file, ENVIRONMENT.DIRECTORY_SEPARATOR.$file) as $location)
			{
				$file_path = $path.'config/'.$location.'.php';
				if (in_array($file_path, $this->is_loaded, TRUE))
				{
					return TRUE;
				}

				if ( ! file_exists($file_path))
				{
					continue;
				}

				include($file_path);

				if ( ! isset($config) OR ! is_array($config))
				{
					if ($fail_gracefully === TRUE)
					{
						return FALSE;
					}

					show_error('Your '.$file_path.' file does not appear to contain a valid configuration array.');
				}

				if ($use_sections === TRUE)
				{
					$this->config[$file] = isset($this->config[$file])
						? array_merge($this->config[$file], $config)
						: $config;
				}
				else
				{
					$this->config = array_merge($this->config, $config);
				}

				$this->is_loaded[] = $file_path;
				$config = NULL;
				$loaded = TRUE;
				log_message('debug', 'Config file loaded: '.$file_path);
			}
		}

		if ($loaded === TRUE)
		{
			return TRUE;
		}
		elseif ($fail_gracefully === TRUE)
		{
			return FALSE;
		}

		show_error('The configuration file '.$file.'.php does not exist.');
	}

	// --------------------------------------------------------------------

	/**
	 * Fetch a config file item
	 *
	 * @param	string	$item	Config item name
	 * @param	string	$index	Index name
	 * @return	string|null	The configuration item or NULL if the item doesn't exist
	 */
	public function item($item, $index = '')
	{
		if ($index == '')
		{
			return isset($this->config[$item]) ? $this->config[$item] : NULL;
		}

		return isset($this->config[$index], $this->config[$index][$item]) ? $this->config[$index][$item] : NULL;
	}

	// --------------------------------------------------------------------

	/**
	 * Fetch a config file item with slash appended (if not empty)
	 *
	 * @param	string		$item	Config item name
	 * @return	string|null	The configuration item or NULL if the item doesn't exist
	 */
	public function slash_item($item)
	{
		if ( ! isset($this->config[$item]))
		{
			return NULL;
		}
		elseif (trim($this->config[$item]) === '')
		{
			return '';
		}

		return rtrim($this->config[$item], '/').'/';
	}

	// --------------------------------------------------------------------

	/**
	 * Site URL
	 *
	 * Returns base_url . index_page [. uri_string]
	 *
	 * @uses	CI_Config::_uri_string()
	 *
	 * @param	string|string[]	$uri	URI string or an array of segments
	 * @param	string	$protocol
	 * @return	string
	 */
	public function site_url($uri = '', $protocol = NULL)
	{
		$base_url = $this->slash_item('base_url');

		if (isset($protocol))
		{
			// For protocol-relative links
			if ($protocol === '')
			{
				$base_url = substr($base_url, strpos($base_url, '//'));
			}
			else
			{
				$base_url = $protocol.substr($base_url, strpos($base_url, '://'));
			}
		}

		if (empty($uri))
		{
			return $base_url.$this->item('index_page');
		}

		$uri = $this->_uri_string($uri);

		if ($this->item('enable_query_strings') === FALSE)
		{
			$suffix = isset($this->config['url_suffix']) ? $this->config['url_suffix'] : '';

			if ($suffix !== '')
			{
				if (($offset = strpos($uri, '?')) !== FALSE)
				{
					$uri = substr($uri, 0, $offset).$suffix.substr($uri, $offset);
				}
				else
				{
					$uri .= $suffix;
				}
			}

			return $base_url.$this->slash_item('index_page').$uri;
		}
		elseif (strpos($uri, '?') === FALSE)
		{
			$uri = '?'.$uri;
		}

		return $base_url.$this->item('index_page').$uri;
	}

	// -------------------------------------------------------------

	/**
	 * Base URL
	 *
	 * Returns base_url [. uri_string]
	 *
	 * @uses	CI_Config::_uri_string()
	 *
	 * @param	string|string[]	$uri	URI string or an array of segments
	 * @param	string	$protocol
	 * @return	string
	 */
	public function base_url($uri = '', $protocol = NULL)
	{
		$base_url = $this->slash_item('base_url');

		if (isset($protocol))
		{
			// For protocol-relative links
			if ($protocol === '')
			{
				$base_url = substr($base_url, strpos($base_url, '//'));
			}
			else
			{
				$base_url = $protocol.substr($base_url, strpos($base_url, '://'));
			}
		}

		return $base_url.$this->_uri_string($uri);
	}

	// -------------------------------------------------------------

	/**
	 * Build URI string
	 *
	 * @used-by	CI_Config::site_url()
	 * @used-by	CI_Config::base_url()
	 *
	 * @param	string|string[]	$uri	URI string or an array of segments
	 * @return	string
	 */
	protected function _uri_string($uri)
	{
		if ($this->item('enable_query_strings') === FALSE)
		{
			is_array($uri) && $uri = implode('/', $uri);
			return ltrim($uri, '/');
		}
		elseif (is_array($uri))
		{
			return http_build_query($uri);
		}

		return $uri;
	}

	// --------------------------------------------------------------------

	/**
	 * System URL
	 *
	 * @deprecated	3.0.0	Encourages insecure practices
	 * @return	string
	 */
	public function system_url()
	{
		$x = explode('/', preg_replace('|/*(.+?)/*$|', '\\1', BASEPATH));
		return $this->slash_item('base_url').end($x).'/';
	}

	// --------------------------------------------------------------------

	/**
	 * Set a config file item
	 *
	 * @param	string	$item	Config item key
	 * @param	string	$value	Config item value
	 * @return	void
	 */
	public function set_item($item, $value)
	{
		$this->config[$item] = $value;
	}

}