http://www.bitscn.com/pdb/php/201411/404680.html
顾名思义，装载器就是加载元素的，使用CI时，经常加载的有：
$this->load->library()
$this->load->view()
$this->load->model()
$this->load->database()
$this->load->helper()
$this->load->config()
$this->load->add_package_path()
代码如下:
/**
* Loader Class
*
* 用户加载views和files，常见的函数有model(),view(),library(),helper()
*
* Controller的好助手，$this->load =& load_class('Loader', 'core');，加载了loader，Controller就无比强大了
*/
class CI_Loader {
protected $_ci_ob_level;
protected $_ci_view_paths = array();
protected $_ci_library_paths = array();
protected $_ci_model_paths = array();
protected $_ci_helper_paths = array();
protected $_base_classes = array(); // Set by the controller class
protected $_ci_cached_vars = array();
protected $_ci_classes = array();
protected $_ci_loaded_files = array();
protected $_ci_models = array();
protected $_ci_helpers = array();
protected $_ci_varmap = array('unit_test' => 'unit',
'user_agent' => 'agent');
public function __construct()
{
//获取缓冲嵌套级别
$this->_ci_ob_level = ob_get_level();
//library路径
$this->_ci_library_paths = array(APPPATH, BASEPATH);
//helper路径
$this->_ci_helper_paths = array(APPPATH, BASEPATH);
//model路径
$this->_ci_model_paths = array(APPPATH);
//view路径
$this->_ci_view_paths = array(APPPATH.'views/' => TRUE);
log_message('debug', "Loader Class Initialized");
}
// --------------------------------------------------------------------
/**
* 初始化Loader
*
*/
public function initialize()
{
$this->_ci_classes = array();
$this->_ci_loaded_files = array();
$this->_ci_models = array();
//将is_loaded（common中记录加载核心类函数）加载的核心类交给_base_classes
$this->_base_classes =& is_loaded();
//加载autoload.php配置中文件
$this->_ci_autoloader();
return $this;
}
// --------------------------------------------------------------------
/**
* 检测类是否加载
*/
public function is_loaded($class)
{
if (isset($this->_ci_classes[$class]))
{
return $this->_ci_classes[$class];
}
return FALSE;
}
// --------------------------------------------------------------------
/**
* 加载Class
*/
public function library($library = '', $params = NULL, $object_name = NULL)
{
if (is_array($library))
{
foreach ($library as $class)
{
$this->library($class, $params);
}
return;
}
//如果$library为空或者已经加载。。。
if ($library == '' OR isset($this->_base_classes[$library]))
{
return FALSE;
}
if ( ! is_null($params) && ! is_array($params))
{
$params = NULL;
}
$this->_ci_load_class($library, $params, $object_name);
}
// --------------------------------------------------------------------
/**
* 加载和实例化model
*/
public function model($model, $name = '', $db_conn = FALSE)
{
//CI支持数组加载多个model
if (is_array($model))
{
foreach ($model as $babe)
{
$this->model($babe);
}
return;
}
if ($model == '')
{
return;
}
$path = '';
// 是否存在子目录
if (($last_slash = strrpos($model, '/')) !== FALSE)
{
// The path is in front of the last slash
$path = substr($model, 0, $last_slash + 1);
// And the model name behind it
$model = substr($model, $last_slash + 1);
}
if ($name == '')
{
$name = $model;
}
if (in_array($name, $this->_ci_models, TRUE))
{
return;
}
$CI =& get_instance();
if (isset($CI->$name))
{
show_error('The model name you are loading is the name of a resource that is already being used: '.$name);
}
$model = strtolower($model); //model文件名全小写
foreach ($this->_ci_model_paths as $mod_path)
{
if ( ! file_exists($mod_path.'models/'.$path.$model.'.php'))
{
continue;
}
if ($db_conn !== FALSE AND ! class_exists('CI_DB'))
{
if ($db_conn === TRUE)
{
$db_conn = '';
}
$CI->load->database($db_conn, FALSE, TRUE);
}
if ( ! class_exists('CI_Model'))
{
load_class('Model', 'core');
}
require_once($mod_path.'models/'.$path.$model.'.php');
$model = ucfirst($model);
$CI->$name = new $model();
//保存在Loader::_ci_models中，以后可以用它来判断某个model是否已经加载过。
$this->_ci_models[] = $name;
return;
}
// couldn't find the model
show_error('Unable to locate the model you have specified: '.$model);
}
// --------------------------------------------------------------------
/**
* 数据库Loader
*/
public function database($params = '', $return = FALSE, $active_record = NULL)
{
// Grab the super object
$CI =& get_instance();
// 是否需要加载db
if (class_exists('CI_DB') AND $return == FALSE AND $active_record == NULL AND isset($CI->db) AND is_object($CI->db))
{
return FALSE;
}
require_once(BASEPATH.'database/DB.php');
if ($return === TRUE)
{
return DB($params, $active_record);
}
// Initialize the db variable. Needed to prevent
// reference errors with some configurations
$CI->db = '';
// Load the DB class
$CI->db =& DB($params, $active_record);
}
// --------------------------------------------------------------------
/**
* 加载数据库工具类
*/
public function dbutil()
{
if ( ! class_exists('CI_DB'))
{
$this->database();
}
$CI =& get_instance();
// for backwards compatibility, load dbforge so we can extend dbutils off it
// this use is deprecated and strongly discouraged
$CI->load->dbforge();
require_once(BASEPATH.'database/DB_utility.php');
require_once(BASEPATH.'database/drivers/'.$CI->db->dbdriver.'/'.$CI->db->dbdriver.'_utility.php');
$class = 'CI_DB_'.$CI->db->dbdriver.'_utility';
$CI->dbutil = new $class();
}
// --------------------------------------------------------------------
/**
* Load the Database Forge Class
*
* @return string
*/
public function dbforge()
{
if ( ! class_exists('CI_DB'))
{
$this->database();
}
$CI =& get_instance();
require_once(BASEPATH.'database/DB_forge.php');
require_once(BASEPATH.'database/drivers/'.$CI->db->dbdriver.'/'.$CI->db->dbdriver.'_forge.php');
$class = 'CI_DB_'.$CI->db->dbdriver.'_forge';
$CI->dbforge = new $class();
}
// --------------------------------------------------------------------
/**
* 加载视图文件
*/
public function view($view, $vars = array(), $return = FALSE)
{
return $this->_ci_load(array('_ci_view' => $view, '_ci_vars' => $this->_ci_object_to_array($vars), '_ci_return' => $return));
}
// --------------------------------------------------------------------
/**
* 加载普通文件
*/
public function file($path, $return = FALSE)
{
return $this->_ci_load(array('_ci_path' => $path, '_ci_return' => $return));
}
// --------------------------------------------------------------------
/**
* 设置变量
*
* Once variables are set they become available within
* the controller class and its "view" files.
*
*/
public function vars($vars = array(), $val = '')
{
if ($val != '' AND is_string($vars))
{
$vars = array($vars => $val);
}
$vars = $this->_ci_object_to_array($vars);
if (is_array($vars) AND count($vars) > 0)
{
foreach ($vars as $key => $val)
{
$this->_ci_cached_vars[$key] = $val;
}
}
}
// --------------------------------------------------------------------
/**
* 检查并获取变量
*/
public function get_var($key)
{
return isset($this->_ci_cached_vars[$key]) ? $this->_ci_cached_vars[$key] : NULL;
}
// --------------------------------------------------------------------
/**
* 加载helper
*/
public function helper($helpers = array())
{
foreach ($this->_ci_prep_filename($helpers, '_helper') as $helper)
{
if (isset($this->_ci_helpers[$helper]))
{
continue;
}
$ext_helper = APPPATH.'helpers/'.config_item('subclass_prefix').$helper.'.php';
// 如果是扩展helper的话
if (file_exists($ext_helper))
{
$base_helper = BASEPATH.'helpers/'.$helper.'.php';
if ( ! file_exists($base_helper))
{
show_error('Unable to load the requested file: helpers/'.$helper.'.php');
}
include_once($ext_helper);
include_once($base_helper);
$this->_ci_helpers[$helper] = TRUE;
log_message('debug', 'Helper loaded: '.$helper);
continue;
}
// 如果不是扩展helper，helper路径中加载helper
foreach ($this->_ci_helper_paths as $path)
{
if (file_exists($path.'helpers/'.$helper.'.php'))
{
include_once($path.'helpers/'.$helper.'.php');
$this->_ci_helpers[$helper] = TRUE;
log_message('debug', 'Helper loaded: '.$helper);
break;
}
}
// 如果该helper还没加载成功的话，说明加载helper失败
if ( ! isset($this->_ci_helpers[$helper]))
{
show_error('Unable to load the requested file: helpers/'.$helper.'.php');
}
}
}
// --------------------------------------------------------------------
/**
* 可以看到helpers调用也是上面的helper,只是helpers的别名而已
*/
public function helpers($helpers = array())
{
$this->helper($helpers);
}
// --------------------------------------------------------------------
/**
* 加载language文件
*/
public function language($file = array(), $lang = '')
{
$CI =& get_instance();
if ( ! is_array($file))
{
$file = array($file);
}
foreach ($file as $langfile)
{
$CI->lang->load($langfile, $lang);
}
}
// --------------------------------------------------------------------
/**
* 加载配置文件
*/
public function config($file = '', $use_sections = FALSE, $fail_gracefully = FALSE)
{
$CI =& get_instance();
$CI->config->load($file, $use_sections, $fail_gracefully);
}
// --------------------------------------------------------------------
/**
* Driver
*
* 加载 driver library
*/
public function driver($library = '', $params = NULL, $object_name = NULL)
{
if ( ! class_exists('CI_Driver_Library'))
{
// we aren't instantiating an object here, that'll be done by the Library itself
require BASEPATH.'libraries/Driver.php';
}
if ($library == '')
{
return FALSE;
}
// We can save the loader some time since Drivers will *always* be in a subfolder,
// and typically identically named to the library
if ( ! strpos($library, '/'))
{
$library = ucfirst($library).'/'.$library;
}
return $this->library($library, $params, $object_name);
}
// --------------------------------------------------------------------
/**
* 添加 Package 路径
*
* 把package路径添加到库，模型，助手，配置路径
*/
public function add_package_path($path, $view_cascade=TRUE)
{
$path = rtrim($path, '/').'/';
array_unshift($this->_ci_library_paths, $path);
array_unshift($this->_ci_model_paths, $path);
array_unshift($this->_ci_helper_paths, $path);
$this->_ci_view_paths = array($path.'views/' => $view_cascade) + $this->_ci_view_paths;
$config =& $this->_ci_get_component('config');
array_unshift($config->_config_paths, $path);
}
// --------------------------------------------------------------------
/**
* 获取Package Paths，默认不包含BASEPATH
*/
public function get_package_paths($include_base = FALSE)
{
return $include_base === TRUE ? $this->_ci_library_paths : $this->_ci_model_paths;
}
// --------------------------------------------------------------------
/**
* 剔除Package Path
*
* Remove a path from the library, model, and helper path arrays if it exists
* If no path is provided, the most recently added path is removed.
*
*/
public function remove_package_path($path = '', $remove_config_path = TRUE)
{
$config =& $this->_ci_get_component('config');
if ($path == '')
{
$void = array_shift($this->_ci_library_paths);
$void = array_shift($this->_ci_model_paths);
$void = array_shift($this->_ci_helper_paths);
$void = array_shift($this->_ci_view_paths);
$void = array_shift($config->_config_paths);
}
else
{
$path = rtrim($path, '/').'/';
foreach (array('_ci_library_paths', '_ci_model_paths', '_ci_helper_paths') as $var)
{
if (($key = array_search($path, $this->{$var})) !== FALSE)
{
unset($this->{$var}[$key]);
}
}
if (isset($this->_ci_view_paths[$path.'views/']))
{
unset($this->_ci_view_paths[$path.'views/']);
}
if (($key = array_search($path, $config->_config_paths)) !== FALSE)
{
unset($config->_config_paths[$key]);
}
}
// 保证应用默认的路径依然存在
$this->_ci_library_paths = array_unique(array_merge($this->_ci_library_paths, array(APPPATH, BASEPATH)));
$this->_ci_helper_paths = array_unique(array_merge($this->_ci_helper_paths, array(APPPATH, BASEPATH)));
$this->_ci_model_paths = array_unique(array_merge($this->_ci_model_paths, array(APPPATH)));
$this->_ci_view_paths = array_merge($this->_ci_view_paths, array(APPPATH.'views/' => TRUE));
$config->_config_paths = array_unique(array_merge($config->_config_paths, array(APPPATH)));
}
// --------------------------------------------------------------------
/**
* Loader
*
* This function is used to load views and files.
* Variables are prefixed with _ci_ to avoid symbol collision with
* variables made available to view files
*
* @param array
* @return void
*/
protected function _ci_load($_ci_data)
{
// Set the default data variables
foreach (array('_ci_view', '_ci_vars', '_ci_path', '_ci_return') as $_ci_val)
{
$$_ci_val = ( ! isset($_ci_data[$_ci_val])) ? FALSE : $_ci_data[$_ci_val];
}
$file_exists = FALSE;
//如果$_ci_path不为空，则说明当前要加载普通文件。Loader::file才会有path
if ($_ci_path != '')
{
$_ci_x = explode('/', $_ci_path);
$_ci_file = end($_ci_x);
}
else
{
$_ci_ext = pathinfo($_ci_view, PATHINFO_EXTENSION);
$_ci_file = ($_ci_ext == '') ? $_ci_view.'.php' : $_ci_view;
foreach ($this->_ci_view_paths as $view_file => $cascade)
{
if (file_exists($view_file.$_ci_file))
{
$_ci_path = $view_file.$_ci_file;
$file_exists = TRUE;
break;
}
if ( ! $cascade)
{
break;
}
}
}
//view文件不存在则会报错
if ( ! $file_exists && ! file_exists($_ci_path))
{
show_error('Unable to load the requested file: '.$_ci_file);
}
// 把CI的所有属性都传递给loader，view中$this指的是loader
$_ci_CI =& get_instance();
foreach (get_object_vars($_ci_CI) as $_ci_key => $_ci_var)
{
if ( ! isset($this->$_ci_key))
{
$this->$_ci_key =& $_ci_CI->$_ci_key;
}
}
/*
* Extract and cache variables
*
* You can either set variables using the dedicated $this->load_vars()
* function or via the second parameter of this function. We'll merge
* the two types and cache them so that views that are embedded within
* other views can have access to these variables.
*/
if (is_array($_ci_vars))
{
$this->_ci_cached_vars = array_merge($this->_ci_cached_vars, $_ci_vars);
}
extract($this->_ci_cached_vars);
/*
* 将视图内容放到缓存区
*
*/
ob_start();
// 支持短标签
if ((bool) @ini_get('short_open_tag') === FALSE AND config_item('rewrite_short_tags') == TRUE)
{
echo eval('?>'.preg_replace("/;*s*?>/", "; ?>", str_replace('<?=', '<?php echo ', file_get_contents($_ci_path))));
}
else
{
include($_ci_path); // include() vs include_once() allows for multiple views with the same name
}
log_message('debug', 'File loaded: '.$_ci_path);
// 是否直接返回view数据
if ($_ci_return === TRUE)
{
$buffer = ob_get_contents();
@ob_end_clean();
return $buffer;
}
//当前这个视图文件是被另一个视图文件通过$this->view()方法引入，即视图文件嵌入视图文件
if (ob_get_level() > $this->_ci_ob_level + 1)
{
ob_end_flush();
}
else
{ ////把缓冲区的内容交给Output组件并清空关闭缓冲区。
$_ci_CI->output->append_output(ob_get_contents());
@ob_end_clean();
}
}
// --------------------------------------------------------------------
/**
* 加载类
*/
protected function _ci_load_class($class, $params = NULL, $object_name = NULL)
{
// 去掉.php和两端的/获取的$class就是类名或目录名+类名
$class = str_replace('.php', '', trim($class, '/'));
// CI允许dir/filename方式
$subdir = '';
if (($last_slash = strrpos($class, '/')) !== FALSE)
{
// 目录
$subdir = substr($class, 0, $last_slash + 1);
// 文件名
$class = substr($class, $last_slash + 1);
}
// 允许加载的类名首字母大写或全小写
foreach (array(ucfirst($class), strtolower($class)) as $class)
{
$subclass = APPPATH.'libraries/'.$subdir.config_item('subclass_prefix').$class.'.php';
// 是否是扩展类
if (file_exists($subclass))
{
$baseclass = BASEPATH.'libraries/'.ucfirst($class).'.php';
if ( ! file_exists($baseclass))
{
log_message('error', "Unable to load the requested class: ".$class);
show_error("Unable to load the requested class: ".$class);
}
// Safety: Was the class already loaded by a previous call?
if (in_array($subclass, $this->_ci_loaded_files))
{
// Before we deem this to be a duplicate request, let's see
// if a custom object name is being supplied. If so, we'll
// return a new instance of the object
if ( ! is_null($object_name))
{
$CI =& get_instance();
if ( ! isset($CI->$object_name))
{
return $this->_ci_init_class($class, config_item('subclass_prefix'), $params, $object_name);
}
}
$is_duplicate = TRUE;
log_message('debug', $class." class already loaded. Second attempt ignored.");
return;
}
include_once($baseclass);
include_once($subclass);
$this->_ci_loaded_files[] = $subclass;
//实例化类
return $this->_ci_init_class($class, config_item('subclass_prefix'), $params, $object_name);
}
// 如果不是扩展，和上面类似
$is_duplicate = FALSE;
foreach ($this->_ci_library_paths as $path)
{
$filepath = $path.'libraries/'.$subdir.$class.'.php';
// Does the file exist? No? Bummer...
if ( ! file_exists($filepath))
{
continue;
}
// Safety: Was the class already loaded by a previous call?
if (in_array($filepath, $this->_ci_loaded_files))
{
// Before we deem this to be a duplicate request, let's see
// if a custom object name is being supplied. If so, we'll
// return a new instance of the object
if ( ! is_null($object_name))
{
$CI =& get_instance();
if ( ! isset($CI->$object_name))
{
return $this->_ci_init_class($class, '', $params, $object_name);
}
}
$is_duplicate = TRUE;
log_message('debug', $class." class already loaded. Second attempt ignored.");
return;
}
include_once($filepath);
$this->_ci_loaded_files[] = $filepath;
return $this->_ci_init_class($class, '', $params, $object_name);
}
} // END FOREACH
// 如果还没有找到该class，最后的尝试是该class会不会在同名的子目录下
if ($subdir == '')
{
$path = strtolower($class).'/'.$class;
return $this->_ci_load_class($path, $params);
}
// 加载失败，报错
if ($is_duplicate == FALSE)
{
log_message('error', "Unable to load the requested class: ".$class);
show_error("Unable to load the requested class: ".$class);
}
}
// --------------------------------------------------------------------
/**
* 实例化已经加载的类
*/
protected function _ci_init_class($class, $prefix = '', $config = FALSE, $object_name = NULL)
{
// 是否有类的配置信息
if ($config === NULL)
{
// Fetch the config paths containing any package paths
$config_component = $this->_ci_get_component('config');
if (is_array($config_component->_config_paths))
{
// Break on the first found file, thus package files
// are not overridden by default paths
foreach ($config_component->_config_paths as $path)
{
// We test for both uppercase and lowercase, for servers that
// are case-sensitive with regard to file names. Check for environment
// first, global next
if (defined('ENVIRONMENT') AND file_exists($path .'config/'.ENVIRONMENT.'/'.strtolower($class).'.php'))
{
include($path .'config/'.ENVIRONMENT.'/'.strtolower($class).'.php');
break;
}
elseif (defined('ENVIRONMENT') AND file_exists($path .'config/'.ENVIRONMENT.'/'.ucfirst(strtolower($class)).'.php'))
{
include($path .'config/'.ENVIRONMENT.'/'.ucfirst(strtolower($class)).'.php');
break;
}
elseif (file_exists($path .'config/'.strtolower($class).'.php'))
{
include($path .'config/'.strtolower($class).'.php');
break;
}
elseif (file_exists($path .'config/'.ucfirst(strtolower($class)).'.php'))
{
include($path .'config/'.ucfirst(strtolower($class)).'.php');
break;
}
}
}
}
if ($prefix == '')
{ //system下library
if (class_exists('CI_'.$class))
{
$name = 'CI_'.$class;
}
elseif (class_exists(config_item('subclass_prefix').$class))
{ //扩展library
$name = config_item('subclass_prefix').$class;
}
else
{
$name = $class;
}
}
else
{
$name = $prefix.$class;
}
// Is the class name valid?
if ( ! class_exists($name))
{
log_message('error', "Non-existent class: ".$name);
show_error("Non-existent class: ".$class);
}
// Set the variable name we will assign the class to
// Was a custom class name supplied? If so we'll use it
$class = strtolower($class);
if (is_null($object_name))
{
$classvar = ( ! isset($this->_ci_varmap[$class])) ? $class : $this->_ci_varmap[$class];
}
else
{
$classvar = $object_name;
}
// Save the class name and object name
$this->_ci_classes[$class] = $classvar;
// 将初始化的类的实例给CI超级句柄
$CI =& get_instance();
if ($config !== NULL)
{
$CI->$classvar = new $name($config);
}
else
{
$CI->$classvar = new $name;
}
}
// --------------------------------------------------------------------
/**
* 自动加载器
*
* autoload.php配置的自动加载文件有：
* | 1. Packages
| 2. Libraries
| 3. Helper files
| 4. Custom config files
| 5. Language files
| 6. Models
*/
private function _ci_autoloader()
{
if (defined('ENVIRONMENT') AND file_exists(APPPATH.'config/'.ENVIRONMENT.'/autoload.php'))
{
include(APPPATH.'config/'.ENVIRONMENT.'/autoload.php');
}
else
{
include(APPPATH.'config/autoload.php');
}
if ( ! isset($autoload))
{
return FALSE;
}
// 自动加载packages,也就是将package_path加入到library，model，helper，config
if (isset($autoload['packages']))
{
foreach ($autoload['packages'] as $package_path)
{
$this->add_package_path($package_path);
}
}
// 加载config文件
if (count($autoload['config']) > 0)
{
$CI =& get_instance();
foreach ($autoload['config'] as $key => $val)
{
$CI->config->load($val);
}
}
// 加载helper和language
foreach (array('helper', 'language') as $type)
{
if (isset($autoload[$type]) AND count($autoload[$type]) > 0)
{
$this->$type($autoload[$type]);
}
}
// 这个好像是为了兼容以前版本的
if ( ! isset($autoload['libraries']) AND isset($autoload['core']))
{
$autoload['libraries'] = $autoload['core'];
}
// 加载libraries
if (isset($autoload['libraries']) AND count($autoload['libraries']) > 0)
{
// 加载db
if (in_array('database', $autoload['libraries']))
{
$this->database();
$autoload['libraries'] = array_diff($autoload['libraries'], array('database'));
}
// 加载所有其他libraries
foreach ($autoload['libraries'] as $item)
{
$this->library($item);
}
}
// Autoload models
if (isset($autoload['model']))
{
$this->model($autoload['model']);
}
}
// --------------------------------------------------------------------
/**
* 返回由对象属性组成的关联数组
*/
protected function _ci_object_to_array($object)
{
return (is_object($object)) ? get_object_vars($object) : $object;
}
// --------------------------------------------------------------------
/**
* 获取CI某个组件的实例
*/
protected function &_ci_get_component($component)
{
$CI =& get_instance();
return $CI->$component;
}
// --------------------------------------------------------------------
/**
* 处理文件名，这个函数主要是返回正确文件名
*/
protected function _ci_prep_filename($filename, $extension)
{
if ( ! is_array($filename))
{
return array(strtolower(str_replace('.php', '', str_replace($extension, '', $filename)).$extension));
}
else
{
foreach ($filename as $key => $val)
{
$filename[$key] = strtolower(str_replace('.php', '', str_replace($extension, '', $val)).$extension);
}
return $filename;
}
}
}