Loader加载类 做要作用 加载file 加载library 加载helper 加载vars 加载config 加载language
以及加载clas 实例化class 、还有自动加载机制（通过配置文件autoload.php实现）
源代码很长的一个类
<?php
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');
// 缓存级别、library helper model view 的path
public function __construct()
{
$this->_ci_ob_level = ob_get_level();
$this->_ci_library_paths = array(APPPATH, BASEPATH);
$this->_ci_helper_paths = array(APPPATH, BASEPATH);
$this->_ci_model_paths = array(APPPATH);
$this->_ci_view_paths = array(APPPATH.'views/' => TRUE);
log_message('debug', "Loader Class Initialized");
}
// 加载实例化的class 加载的文件 加载实例化model 加载实例化的核心类
public function initialize()
{
$this->_ci_classes = array();
$this->_ci_loaded_files = array();
$this->_ci_models = array();
$this->_base_classes =& is_loaded();
$this->_ci_autoloader();
return $this;
}
// 已经实例化的类不会重复实例化
public function is_loaded($class)
{
if (isset($this->_ci_classes[$class]))
{
return $this->_ci_classes[$class];
}
return FALSE;
}
// 加载library 的类
public function library($library = '', $params = NULL, $object_name = NULL)
{
// 数组
if (is_array($library))
{
foreach ($library as $class)
{
$this->library($class, $params);
}
return;
}
if ($library == '' OR isset($this->_base_classes[$library]))
{//library名称为空 或者library 跟核心类的名称冲突
return FALSE;
}
if ( ! is_null($params) && ! is_array($params))
{
$params = NULL;
}
$this->_ci_load_class($library, $params, $object_name);
}
public function model($model, $name = '', $db_conn = FALSE)
{
if (is_array($model))
{
foreach ($model as $babe)
{
$this->model($babe);
}
return;
}
if ($model == '')
{
return;//model名为空
}
$path = '';
if (($last_slash = strrpos($model, '/')) !== FALSE)//last_slash 最后出现 '/' 的位置
{
$path = substr($model, 0, $last_slash + 1);//路径
$model = substr($model, $last_slash + 1);//文件名
}
if ($name == '')
{
$name = $model;//别名为空就不用别名了
}
if (in_array($name, $this->_ci_models, TRUE))
{
return;//model name已经被加载 停止加载操作
}
$CI =& get_instance();
if (isset($CI->$name))
{
// 如果CI类中的属性名称跟现在的model name一样的话 会出现这样的错误报告
// so model name 注意不要与controller成员属性名称发生冲突
show_error('The model name you are loading is the name of a resource that is already being used: '.$name);
}
// 这里注意 模型文件用小写字母命名 这里将名称全转成小写了
$model = strtolower($model);
foreach ($this->_ci_model_paths as $mod_path)//遍历路径
{
if ( ! file_exists($mod_path.'models/'.$path.$model.'.php'))
{
continue;// 当前路径中文件不存在
}
if ($db_conn !== FALSE AND ! class_exists('CI_DB'))
{
if ($db_conn === TRUE)
{
$db_conn = '';
}
// load DB
$CI->load->database($db_conn, FALSE, TRUE);
}
if ( ! class_exists('CI_Model'))
{
load_class('Model', 'core');// 加载CI_Model model基础类
}
//加载文件
require_once($mod_path.'models/'.$path.$model.'.php');
// 文件里面的类名 首字母大写
$model = ucfirst($model);
//实例化 并且赋值给CI的属性
$CI->$name = new $model();
$this->_ci_models[] = $name;//加载model 标志
return;
}
show_error('Unable to locate the model you have specified: '.$model);// couldn't find the model
}
public function database($params = '', $return = FALSE, $active_record = NULL)
{
// Grab the super object
$CI =& get_instance();
// Do we even need to load the database class?
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);
}
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();
}
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 $class();
}
public function view($view, $vars = array(), $return = FALSE)
{
return $this->_ci_load(array('_ci_view' => $view, '_ci_vars' => $this->_ci_object_to_array($vars), '_ci_return' => $return));
}
public function file($path, $return = FALSE)
{
return $this->_ci_load(array('_ci_path' => $path, '_ci_return' => $return));
}
//添加变量到缓存中 并且这里添加的变量能够被controller的所有function使用(传递到view)
public function vars($vars = array(), $val = '')
{
if ($val != '' AND is_string($vars))
{
// vars is key and val is value and 拼接两者成为数组
$vars = array($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] = $val; //添加到_ci_cached_vars
}
}
}
public function get_var($key)
{
// return _ci_cached_vars
return isset($this->_ci_cached_vars[$key]) ? $this->_ci_cached_vars[$key] : NULL;
}
public function helper($helpers = array())
{
foreach ($this->_ci_prep_filename($helpers, '_helper') as $helper)//遍历helper数组
{
if (isset($this->_ci_helpers[$helper]))
{
// 已经加载 去其他目录查找
continue;
}
// helper扩展的路径
$ext_helper = APPPATH.'helpers/'.config_item('subclass_prefix').$helper.'.php';
if (file_exists($ext_helper))
{
$base_helper = BASEPATH.'helpers/'.$helper.'.php';//基础helper路径
if ( ! file_exists($base_helper))
{//基础helper不存在
show_error('Unable to load the requested file: helpers/'.$helper.'.php');
}
//加载基础helper函数跟扩展helper函数
include_once($ext_helper);
include_once($base_helper);
$this->_ci_helpers[$helper] = TRUE;//标志已经加载过
log_message('debug', 'Helper loaded: '.$helper);
continue;
}
//遍历
foreach ($this->_ci_helper_paths as $path)
{
if (file_exists($path.'helpers/'.$helper.'.php'))
{
//helper文件已经存在就加载
include_once($path.'helpers/'.$helper.'.php');
$this->_ci_helpers[$helper] = TRUE;
log_message('debug', 'Helper loaded: '.$helper);
break;
}
}
if ( ! isset($this->_ci_helpers[$helper]))
{
show_error('Unable to load the requested file: helpers/'.$helper.'.php');
}
}
}
public function helpers($helpers = array())
{
$this->helper($helpers);
}
public function language($file = array(), $lang = '')
{
$CI =& get_instance();
if ( ! is_array($file))
{
$file = array($file);
}
foreach ($file as $langfile)
{
$CI->lang->load($langfile, $lang);
}
}
public function config($file = '', $use_sections = FALSE, $fail_gracefully = FALSE)
{
$CI =& get_instance();
$CI->config->load($file, $use_sections, $fail_gracefully);
}
public function driver($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, $object_name);
}
public function add_package_path($path, $view_cascade=TRUE)
{
// 添加路径
$path = rtrim($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;
// Add config file path
$config =& $this->_ci_get_component('config');
array_unshift($config->_config_paths, $path);
}
public function get_package_paths($include_base = FALSE)
{
return $include_base === TRUE ? $this->_ci_library_paths : $this->_ci_model_paths;
}
public function remove_package_path($path = '', $remove_config_path = TRUE)
{
// 删除指定的路径
$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]);
}
}
// make sure the application default paths are still in the array
$this->_ci_library_paths = array_unique(array_merge($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)));
}
/*
加载文件 最主要的功能是加载view文件
*/
protected function _ci_load($_ci_data)
{
//初始化变量 不存在值就是FALSE
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];
}
$file_exists = FALSE;//文件存在标志
if ($_ci_path != '')
{
$_ci_x = explode('/', $_ci_path);
$_ci_file = end($_ci_x);//文件名
}
else
{
$_ci_ext = pathinfo($_ci_view, PATHINFO_EXTENSION);
$_ci_file = ($_ci_ext == '') ? $_ci_view.'.php' : $_ci_view;//默认扩展名.php
foreach ($this->_ci_view_paths as $view_file => $cascade) //遍历view path
{
if (file_exists($view_file.$_ci_file))
{
// 找到文件 设置 _ci_path 标志文件存在
$_ci_path = $view_file.$_ci_file;
$file_exists = TRUE;
break;
}
if ( ! $cascade)
{
break;
}
}
}
if ( ! $file_exists && ! file_exists($_ci_path))
{//没找到或者路径不存在
show_error('Unable to load the requested file: '.$_ci_file);
}
$_ci_CI =& get_instance();
foreach (get_object_vars($_ci_CI) as $_ci_key => $_ci_var)
{
/*
将CI类里面的对象绑定到本类
也就是说 在 CI_Controller中调用class 可直接 $this->input->get('key')
现在在CI_Loader里面同样能这样调用
*/
if ( ! isset($this->$_ci_key))
{
$this->$_ci_key =& $_ci_CI->$_ci_key;
}
}
if (is_array($_ci_vars))
{//合并_ci_vars 到 _ci_cached_vars
$this->_ci_cached_vars = array_merge($this->_ci_cached_vars, $_ci_vars);
}
extract($this->_ci_cached_vars);
// 激活缓冲区
ob_start();
if ((bool) @ini_get('short_open_tag') === FALSE AND config_item('rewrite_short_tags') == TRUE)
{//替换 <?= 为 <?php echo
echo eval('?>'.preg_replace("/;*\s*\?>/", "; ?>", str_replace('<?=', '<?php echo ', file_get_contents($_ci_path))));
}
else
{
// include() vs include_once() allows for multiple views with the same name
include($_ci_path);
}
log_message('debug', 'File loaded: '.$_ci_path);
if ($_ci_return === TRUE)
{
// 返回缓冲区内容
// return buffer content
$buffer = ob_get_contents();
@ob_end_clean();
return $buffer;
}
if (ob_get_level() > $this->_ci_ob_level + 1)
{
ob_end_flush();
}
else
{
// 合并多个缓冲区的内容
$_ci_CI->output->append_output(ob_get_contents());
@ob_end_clean();
}
}
/*
加载类
*/
protected function _ci_load_class($class, $params = NULL, $object_name = NULL)
{
$class = str_replace('.php', '', trim($class, '/'));
$subdir = '';
if (($last_slash = strrpos($class, '/')) !== FALSE)
{
$subdir = substr($class, 0, $last_slash + 1);//文件夹路径
$class = substr($class, $last_slash + 1);//类文件名（没有后缀）
}
//两边查找 一遍首字母大写 一遍全小写
foreach (array(ucfirst($class), strtolower($class)) as $class)
{
//library的扩展class 文件路径
$subclass = APPPATH.'libraries/'.$subdir.config_item('subclass_prefix').$class.'.php';
//扩展library class存在 找到基础类(被扩展的类)
if (file_exists($subclass))
{
$baseclass = BASEPATH.'libraries/'.ucfirst($class).'.php';
if ( ! file_exists($baseclass))
{//基础类不存在
log_message('error', "Unable to load the requested class: ".$class);
show_error("Unable to load the requested class: ".$class);
}
// subclass文件已经加载过 类的别名不空 并且名字不与CI成员属性发生冲突 实例化类并返回
if (in_array($subclass, $this->_ci_loaded_files))
{
if ( ! is_null($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', $class." class already loaded. Second attempt ignored.");
return;
}
// 加载基础类跟扩展类两个文件
include_once($baseclass);
include_once($subclass);
$this->_ci_loaded_files[] = $subclass;//标记已经加载
// 实例化class
return $this->_ci_init_class($class, config_item('subclass_prefix'), $params, $object_name);
}
$is_duplicate = FALSE;
//遍历library路径
foreach ($this->_ci_library_paths as $path)
{
$filepath = $path.'libraries/'.$subdir.$class.'.php';
if ( ! file_exists($filepath))
{
continue;//不存在继续找
}
//已加载过文件没什么问题就实例化
if (in_array($filepath, $this->_ci_loaded_files))
{
if ( ! is_null($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', $class." class already loaded. Second attempt ignored.");
return;
}
// 加载文件 标记已经加载 实例化class
include_once($filepath);
$this->_ci_loaded_files[] = $filepath;
return $this->_ci_init_class($class, '', $params, $object_name);
}
}
// 一次猜测尝试
if ($subdir == '')
{
$path = strtolower($class).'/'.$class;
return $this->_ci_load_class($path, $params);
}
if ($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class
*/
protected function _ci_init_class($class, $prefix = '', $config = FALSE, $object_name = NULL)
{
if ($config === NULL)
{
// 实例化class的时候config作为实例化参数 为空用config class 加载对应class的配置文件 用参数实例化
$config_component = $this->_ci_get_component('config');
if (is_array($config_component->_config_paths))
{
foreach ($config_component->_config_paths as $path)
{
if (defined('ENVIRONMENT') AND file_exists($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 == '')
{
// 加前缀 扩展前缀 不加前缀分别检测class是否存在
if (class_exists('CI_'.$class))
{
$name = 'CI_'.$class;
}
elseif (class_exists(config_item('subclass_prefix').$class))
{
$name = config_item('subclass_prefix').$class;
}
else
{
$name = $class;
}
}
else
{
$name = $prefix.$class;
}
if ( ! class_exists($name))
{
// 请求实例化的class不存在
log_message('error', "Non-existent class: ".$name);
show_error("Non-existent class: ".$class);
}
// class的名字都转变成了小写
$class = strtolower($class);
// 类的别名
if (is_null($object_name))
{
$classvar = ( ! isset($this->_ci_varmap[$class])) ? $class : $this->_ci_varmap[$class];
}
else
{
$classvar = $object_name;
}
$this->_ci_classes[$class] = $classvar;//标记加载过
// 实例化
$CI =& get_instance();
if ($config !== NULL)
{
$CI->$classvar = new $name($config);
}
else
{
$CI->$classvar = new $name;
}
}
// 通过config里面的autoload实现自动加载
private function _ci_autoloader()
{
if (defined('ENVIRONMENT') AND file_exists(APPPATH.'config/'.ENVIRONMENT.'/autoload.php'))
{
include(APPPATH.'config/'.ENVIRONMENT.'/autoload.php');
}
else
{
include(APPPATH.'config/autoload.php');
}
if ( ! isset($autoload))
{
return FALSE;
}
if (isset($autoload['packages']))
{
foreach ($autoload['packages'] as $package_path)
{
$this->add_package_path($package_path);
}
}
if (count($autoload['config']) > 0)
{
$CI =& get_instance();
foreach ($autoload['config'] as $key => $val)
{
$CI->config->load($val);
}
}
foreach (array('helper', 'language') as $type)
{
if (isset($autoload[$type]) AND count($autoload[$type]) > 0)
{
$this->$type($autoload[$type]);
}
}
if ( ! isset($autoload['libraries']) AND isset($autoload['core']))
{
// 出现名称冲突 优先加载core
$autoload['libraries'] = $autoload['core'];
}
if (isset($autoload['libraries']) AND count($autoload['libraries']) > 0)
{
if (in_array('database', $autoload['libraries']))
{
$this->database();
$autoload['libraries'] = array_diff($autoload['libraries'], array('database'));
}
foreach ($autoload['libraries'] as $item)
{
$this->library($item);
}
}
if (isset($autoload['model']))
{
$this->model($autoload['model']);
}
}
// string get_object_vars() 字符串的形式返回对象变量
protected function _ci_object_to_array($object)
{
return (is_object($object)) ? get_object_vars($object) : $object;
}
protected function &_ci_get_component($component)
{
$CI =& get_instance();
return $CI->$component;
}
/*
1、str_replace('_helper','',filename) myHelper_helper.php-->myHelper.php
2、str_replace('.php','',filename) myHelper.php-->myHelper
3、array(myhelper_helper);
整个过程是把helper函数的文件名称初始化成 name_helper
*/
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;
}
}
}
/*
is_loaded
library
model
view
file
helper
language
config
vars
get_var
add_package_path
get_package_paths
remove_package_path
_ci_load 加载文件 主要用于view
_ci_load_class 加载class 主要用于library
_ci_init_class 实例化class 主要被_ci_load_class 调用
_ci_autoloader 自动加载
*/Code Tips ：
后面的4个函数写法很值得借鉴 还有就是package的设计思路值得学习
特别是library的加载 通过检测_ci_load_file 检测文件是否已经加载 已经加载的class只需要实例化就ok
_ci_init_class 里面的通过配置文件实例化class的设计方式值得借鉴