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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: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,$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 h3ly discouraged
$CI->load->dbforge();
require_once(BASEPATH.'database/DB_utility.php');
require_once(BASEPATH.'database/drivers/'.$CI->db->dbdriver.'/'.$CI->db->dbdriver.'_utility.php');
$class = 'CIDB'.$CI->db->dbdriver.'_utility';
$CI->dbutil = new $class();
}
// --------------------------------------------------------------------
/**
- Load the Database Forge Class
-
- @returnstring
*/
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');
$class = 'CIDB'.$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($library = '',$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,$object_name);
}
// --------------------------------------------------------------------
/**
- 添加 Package 路径
-
- 把package路径添加到库，模型，助手，配置路径
*/
public function add_package_path($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.
-
（编辑：安卓应用网）
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