CodeIgniter框架鉤子機制實現(xiàn)方法【hooks類】
本文實例講述了CodeIgniter框架鉤子機制實現(xiàn)方法。分享給大家供大家參考,具體如下:
記得上一次去到喜啦面試,面試官問我一個問題:codeigniter是如何實現(xiàn)鉤子機制的?
當時答不上來,后來回來之后查了一些資料才明白,所以在這里記錄一下:
codeigniter的鉤子是這樣實現(xiàn)的:首先在框架的核心文件system/core/CodeIniter.php文件的 122行,載入Hooks類,接著在該文件中定義了幾個掛載點,比如pre_system(129行)、post_controller_constructor(295行)等,并在這些掛載點上面執(zhí)行hooks類的_call_hook() 方法。
另附codeigniter的hooks類的源代碼:
<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
/**
* CodeIgniter
*
* An open source application development framework for PHP 5.1.6 or newer
*
* @package CodeIgniter
* @author EllisLab Dev Team
* @copyright Copyright (c) 2008 - 2014, EllisLab, Inc.
* @copyright Copyright (c) 2014 - 2015, British Columbia Institute of Technology (http://bcit.ca/)
* @license http://codeigniter.com/user_guide/license.html
* @link http://codeigniter.com
* @since Version 1.0
* @filesource
*/
// ------------------------------------------------------------------------
/**
* CodeIgniter Hooks Class
*
* Provides a mechanism to extend the base system without hacking.
*
* @package CodeIgniter
* @subpackage Libraries
* @category Libraries
* @author EllisLab Dev Team
* @link http://codeigniter.com/user_guide/libraries/encryption.html
*/
class CI_Hooks {
/**
* Determines wether hooks are enabled
*
* @var bool
*/
var $enabled = FALSE;
/**
* List of all hooks set in config/hooks.php
*
* @var array
*/
var $hooks = array();
/**
* Determines wether hook is in progress, used to prevent infinte loops
*
* @var bool
*/
var $in_progress = FALSE;
/**
* Constructor
*
*/
function __construct()
{
$this->_initialize();
log_message('debug', "Hooks Class Initialized");
}
// --------------------------------------------------------------------
/**
* Initialize the Hooks Preferences
*
* @access private
* @return void
*/
function _initialize()
{
$CFG =& load_class('Config', 'core');
// If hooks are not enabled in the config file
// there is nothing else to do
if ($CFG->item('enable_hooks') == FALSE)
{
return;
}
// Grab the "hooks" definition file.
// If there are no hooks, we're done.
if (defined('ENVIRONMENT') AND is_file(APPPATH.'config/'.ENVIRONMENT.'/hooks.php'))
{
include(APPPATH.'config/'.ENVIRONMENT.'/hooks.php');
}
elseif (is_file(APPPATH.'config/hooks.php'))
{
include(APPPATH.'config/hooks.php');
}
if ( ! isset($hook) OR ! is_array($hook))
{
return;
}
$this->hooks =& $hook;
$this->enabled = TRUE;
}
// --------------------------------------------------------------------
/**
* Call Hook
*
* Calls a particular hook
*
* @access private
* @param string the hook name
* @return mixed
*/
function _call_hook($which = '')
{
if ( ! $this->enabled OR ! isset($this->hooks[$which]))
{
return FALSE;
}
if (isset($this->hooks[$which][0]) AND is_array($this->hooks[$which][0]))
{
foreach ($this->hooks[$which] as $val)
{
$this->_run_hook($val);
}
}
else
{
$this->_run_hook($this->hooks[$which]);
}
return TRUE;
}
// --------------------------------------------------------------------
/**
* Run Hook
*
* Runs a particular hook
*
* @access private
* @param array the hook details
* @return bool
*/
function _run_hook($data)
{
if ( ! is_array($data))
{
return FALSE;
}
// -----------------------------------
// Safety - Prevents run-away loops
// -----------------------------------
// If the script being called happens to have the same
// hook call within it a loop can happen
if ($this->in_progress == TRUE)
{
return;
}
// -----------------------------------
// Set file path
// -----------------------------------
if ( ! isset($data['filepath']) OR ! isset($data['filename']))
{
return FALSE;
}
$filepath = APPPATH.$data['filepath'].'/'.$data['filename'];
if ( ! file_exists($filepath))
{
return FALSE;
}
// -----------------------------------
// Set class/function name
// -----------------------------------
$class = FALSE;
$function = FALSE;
$params = '';
if (isset($data['class']) AND $data['class'] != '')
{
$class = $data['class'];
}
if (isset($data['function']))
{
$function = $data['function'];
}
if (isset($data['params']))
{
$params = $data['params'];
}
if ($class === FALSE AND $function === FALSE)
{
return FALSE;
}
// -----------------------------------
// Set the in_progress flag
// -----------------------------------
$this->in_progress = TRUE;
// -----------------------------------
// Call the requested class and/or function
// -----------------------------------
if ($class !== FALSE)
{
if ( ! class_exists($class))
{
require($filepath);
}
$HOOK = new $class;
$HOOK->$function($params);
}
else
{
if ( ! function_exists($function))
{
require($filepath);
}
$function($params);
}
$this->in_progress = FALSE;
return TRUE;
}
}
// END CI_Hooks class
/* End of file Hooks.php */
/* Location: ./system/core/Hooks.php */
可以看出codeigniter實現(xiàn)鉤子機制的方式不夠優(yōu)雅,其實完全可以使用觀察者模式來實現(xiàn)鉤子機制,將掛載點當做監(jiān)聽的事件。
更多關于CodeIgniter相關內容感興趣的讀者可查看本站專題:《codeigniter入門教程》、《CI(CodeIgniter)框架進階教程》、《php優(yōu)秀開發(fā)框架總結》、《ThinkPHP入門教程》、《ThinkPHP常用方法總結》、《Zend FrameWork框架入門教程》、《php面向對象程序設計入門教程》、《php+mysql數(shù)據(jù)庫操作入門教程》及《php常見數(shù)據(jù)庫操作技巧匯總》
希望本文所述對大家基于CodeIgniter框架的PHP程序設計有所幫助。
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