CI框架中一个类中调用另一个类中已经加载对象测试

controller.php

 <?php
 class CI_Controller {

     private static $instance;

     public function __construct()
     {
         self::$instance =& $this;

         foreach (is_loaded() as $var => $class)
         {
             $this->$var =& load_class($class);
             $obj = $this->$var;
             printf("var: |%s|, class: |%s|, obj: |%s|\n\n", $var, $class, var_export($obj, true));
         }
     }

     public static function &get_instance()
     {
         return self::$instance;
     }

     public function get()
     {
         require 'model.php';
         $model = new CI_Model();
         $str = $model -> invoteClass();
         return $str;
     }
 }
 ?>

model.php

 <?php
 class CI_Model {
     public function __construct()
     {
     }

     /**
      * 这个地方的__get魔术方法使用非常巧妙，值得研究一下
      * 允许model层的类去访问对象$CI所指向的类中已经加载的类
      *
      * __get
      *
      * Allows models to access CI's loaded classes using the same
      * syntax as controllers.
      *
      * @param   string
      * @access private
      */
     public function __get($key)
     {
         $CI = &get_instance();
         printf("inner %s\n\n", __METHOD__);
         return $CI->$key;
     }

     public function invoteClass()
     {
         //$this->appa调用魔术方法__get，魔术方法__get调用类CI_Controller中的成员变量appa
         $obj = $this->appa;
         echo 'inner ' . __METHOD__ . "\n\n";
         printf("obj is: |%s|\n\n", var_export($obj, true));
         printf("obj->getApp: %s\n\n", $obj->getApp());

         $obj = $this->appb;
         echo 'inner ' . __METHOD__ . "\n\n";
         printf("obj is: |%s|\n\n", var_export($obj, true));
         printf("obj->getApp: %s\n\n", $obj->getApp());
     }
 }
 ?>

common.php

 <?php
 if ( ! function_exists('load_class'))
 {
     function &load_class($class)
     {
         static $_classes = array();

         // Does the class exist?  If so, we're done...
         // 如果要加载的类以前已经实例化过，则直接返回它
         if (isset($_classes[$class]))
         {
             return $_classes[$class];
         }

         if (file_exists($class.'.php'))
         {
             require($class.'.php');
         }

         // Keep track of what we just loaded
         //将所有加载过的类保存在静态数组_is_loaded中，
         is_loaded($class);

         //实例化类$name(比如CI_Input)，然后将实例化后的类保存在静态变量$_classes中，避免下次重复实例化
         $_classes[$class] = new $class();
         return $_classes[$class];
     }
 }

 // --------------------------------------------------------------------

 /**
 * Keeps track of which libraries have been loaded.  This function is
 * called by the load_class() function above
 *
 * @access   public
 * @return   array
 */
 if ( ! function_exists('is_loaded'))
 {
     function &is_loaded($class = '')
     {
         static $_is_loaded = array();

         if ($class != '')
         {
             $_is_loaded[strtolower($class)] = $class;
         }

         return $_is_loaded;
     }
 }

 function &get_instance()
 {
     return CI_Controller::get_instance();
 }
 ?>

appa.php

 <?php
 class appA {
     public function __construct() {
     }

     public function getApp() {
         return 'this is appa';
     }
 }

 ?>

appb.php

 <?php
 class appB {
     public function __construct() {
     }

     public function getApp() {
         return 'this is appb';
     }
 }
 ?>

index.php

 <?php
 require 'controller.php';
 require 'common.php';

 load_class('appA');
 load_class('appB');
 $controller = new CI_Controller();
 echo 'inner ' . __FILE__ . "\n\n";
 $controller->get();
 ?>

运行php index.php输出结果如下:

E:\myphp\research\CodeIgniter_2.2.0\ci_study>php index.php
var: |appa|, class: |appA|, obj: |appA::__set_state(array(
))|

var: |appb|, class: |appB|, obj: |appB::__set_state(array(
))|

inner E:\myphp\research\CodeIgniter_2.2.0\ci_study\index.php

inner CI_Model::__get

inner CI_Model::invoteClass

obj is: |appA::__set_state(array(
))|

obj->getApp: this is appa

inner CI_Model::__get

inner CI_Model::invoteClass

obj is: |appB::__set_state(array(
))|

obj->getApp: this is appb

类CI_Model中并没有加载类appA与appB，确可以调用这两个类中的方法并取得数据，这里巧炒的采用了魔术方法__get的功能，并采用了单实例的设计模式实例了上述的调用过程，CI框架此处调用实在是巧炒，非常值得学习借鉴。