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。