本文实例讲述了CodeIgniter框架钩子机制实现方法。分享给大家供大家参考,具体如下:
记得上一次去到喜啦面试,面试官问我一个问题:codeigniter是如何实现钩子机制的?
当时答不上来,后来回来之后查了一些资料才明白,所以在这里记录一下:
codeigniter的钩子是这样实现的:首先在框架的核心文件stem/core/CodeIniter.PHP文件的 122行,载入Hooks类,接着在该文件中定义了几个挂载点,比如pre_system
(129行)、post_controller_constructor
(295行)等,并在这些挂载点上面执行hooks类的_call_hook()
方法。
另附codeigniter的hooks类的源代码:
/**
- 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()
{
$CFG =& load_class('Config','core');
// If hooks are not enabled in the con<a href="/tag/fig/" target="_blank" class="keywords">fig</a> file
// there is <a href="/tag/nothing/" target="_blank" class="keywords">nothing</a> else to do
if ($CFG->item('enable_hooks') == FALSE)
{
return;
}
// Grab the "hooks" de<a href="/tag/Finitio/" target="_blank" class="keywords">Finitio</a>n file.
// If there are no hooks,we're done.
if (defined('ENVIRONMENT') AND is_file(APPPATH.'con<a href="/tag/fig/" target="_blank" class="keywords">fig</a>/'.ENVIRONMENT.'/hooks.<a href="/tag/PHP/" target="_blank" class="keywords">PHP</a>'))
{
include(APPPATH.'con<a href="/tag/fig/" target="_blank" class="keywords">fig</a>/'.ENVIRONMENT.'/hooks.<a href="/tag/PHP/" target="_blank" class="keywords">PHP</a>');
}
elseif (is_file(APPPATH.'con<a href="/tag/fig/" target="_blank" class="keywords">fig</a>/hooks.<a href="/tag/PHP/" target="_blank" class="keywords">PHP</a>'))
{
include(APPPATH.'con<a href="/tag/fig/" target="_blank" class="keywords">fig</a>/hooks.<a href="/tag/PHP/" target="_blank" class="keywords">PHP</a>');
}
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;
$p<a href="/tag/ara/" target="_blank" class="keywords">ara</a>ms = '';
if (isset($data['class']) AND $data['class'] != '')
{
$class = $data['class'];
}
if (isset($data['function']))
{
$function = $data['function'];
}
if (isset($data['p<a href="/tag/ara/" target="_blank" class="keywords">ara</a>ms']))
{
$p<a href="/tag/ara/" target="_blank" class="keywords">ara</a>ms = $data['p<a href="/tag/ara/" target="_blank" class="keywords">ara</a>ms'];
}
if ($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($p<a href="/tag/ara/" target="_blank" class="keywords">ara</a>ms);
}
else
{
if ( ! function_exists($function))
{
require($filepath);
}
$function($p<a href="/tag/ara/" target="_blank" class="keywords">ara</a>ms);
}
$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实现钩子机制的方式不够优雅,其实完全可以使用观察者模式来实现钩子机制,将挂载点当做监听的事件。
更多关于CodeIgniter相关内容感兴趣的读者可查看本站专题:《》、《》、《》、《》、《》、《》、《》、《》及《PHP常见数据库操作技巧汇总》
希望本文所述对大家基于CodeIgniter框架的PHP程序设计有所帮助。
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