zendframework源码浅析之Zend_Loader

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内容摘要

PHP的autoload自动加载机制
Zend_Loader的源码分析

PHP的autoload自动加载机制

PHP的autoload大致包括两种方法：__autoload和spl方法。

1.1 __autoload方法

1.1.1函数名称：

__autoload

1.1.2功能：

尝试加载未定义的类

1.1.3函数原型：

void__autoload ( string $class )

1.1.4实例：

<?php// we've writen this code where we needfunction __autoload($classname) {    $filename = "./". $classname .".php";    include_once($filename);}// we've called a class ***$obj = new myClass();?>

1.2 spl_autoload 方法

1.2.1函数名称：

spl_autoload

1.2.2功能：

__autoload()函数的默认实现。本函数提供了__autoload()的一个默认实现。如果不使用任何参数调用 autoload_register() 函数，则以后在进行 __autoload() 调用时会自动使用此函数。

1.2.3函数原型：

voidspl_autoload ( string $class_name [,string $file_extensions ] )

1.2.4实例：

<?phpclass Loader{           /**     * Controller Directory Path     *     * @var Array     * @access protected     */    protected $_controllerDirectoryPath = array();       /**     * Model Directory Path     *     * @var Array     * @access protected     */    protected $_modelDirectoryPath = array();       /**     * Library Directory Path     *     * @var Array     * @access protected     */    protected $_libraryDirectoryPath = array();          /**     * Constructor     * Constant contain my full path to Model, View, Controllers and Lobrary-     * Direcories.     *     * @Constant MPATH,VPATH,CPATH,LPATH     */        public function __construct()    {        $this->modelDirectoryPath      = MPATH;        $this->viewDirectoryPath        = VPATH;        $this->controllerDirectoryPath = CPATH;        $this->libraryDirectoryPath     = LPATH;               spl_autoload_register(array($this,'load_controller'));        spl_autoload_register(array($this,'load_model'));        spl_autoload_register(array($this,'load_library'));          log_message('debug',"Loader Class Initialized");    }    /**     *-----------------------------------------------------     * Load Library     *-----------------------------------------------------     * Method for load library.     * This method return class object.     *     * @library String     * @param String     * @access public     */       public function load_library($library, $param = null)    {        if (is_string($library)) {            return $this->initialize_class($library);        }        if (is_array($library)) {            foreach ($library as $key) {                return $this->initialize_class($library);            }        }                   }    /**     *-----------------------------------------------------     * Initialize Class     *-----------------------------------------------------     * Method for initialise class     * This method return new object.     * This method can initialize more class using (array)     *     * @library String|Array     * @param String     * @access public     */       public function initialize_class($library)    {        try {            if (is_array($library)) {                foreach($library as $class) {                    $arrayObject =  new $class;                }                           return $this;            }            if (is_string($library)) {                $stringObject = new $library;            }else {                throw new ISException('Class name must be string.');            }            if (null == $library) {                throw new ISException('You must enter the name of the class.');            }        } catch(Exception $exception) {            echo $exception;        }    }          /**     * Autoload Controller class     *     * @param  string $class     * @return object     */        public function load_controller($controller)    {        if ($controller) {            set_include_path($this->controllerDirectoryPath);            spl_autoload_extensions('.php');            spl_autoload($class);        }    }            /**     * Autoload Model class     *     * @param  string $class     * @return object     */        public function load_models($model)    {        if ($model) {            set_include_path($this->modelDirectoryPath);            spl_autoload_extensions('.php');            spl_autoload($class);        }    }            /**     * Autoload Library class     *     * @param  string $class     * @return object     */        public function load_library($library)    {        if ($library) {            set_include_path($this->libraryDirectoryPath);            spl_autoload_extensions('.php');            spl_autoload($class);        }    }      }?>

</pre><p>2.Zend_Loader的源码分析</p><p>    2.1 Zend_Loder的结构</p><p>         <img src="http://img.blog.csdn.net/20150702104548408?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQvcXFfMjk0Nzk4OTc=/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center" alt="" /></p><p>    2.2 剖析</p><p>           Zend/Loader/Autoloader.php      </p><p>           2.2.1 当PHP遇到不认识的类时，尝试自动加载这个类。通过spl_autoload_register方法，告诉PHP，用什么来加载我们的类。</p><p>           __construct方法    ：<pre name="code" class="php">     protected function __construct()     {           spl_autoload_register(array(__CLASS__, 'autoload'));           $this->_internalAutoloader = array($this, '_autoload');     }

autoload方法：

    public static function autoload($class)    {        $self = self::getInstance();        foreach ($self->getClassAutoloaders($class) as $autoloader) {            if ($autoloader instanceof Zend_Loader_Autoloader_Interface) {                if ($autoloader->autoload($class)) {                    return true;                }            } elseif (is_array($autoloader)) {                if (call_user_func($autoloader, $class)) {                    return true;                }            } elseif (is_string($autoloader) || is_callable($autoloader)) {                if ($autoloader($class)) {                    return true;                }            }        }        return false;    }

_autoload方法：

    protected function _autoload($class)    {        $callback = $this->getDefaultAutoloader();        try {            if ($this->suppressNotFoundWarnings()) {                @call_user_func($callback, $class);            } else {                call_user_func($callback, $class);            }            return $class;        } catch (Zend_Exception $e) {            return false;        }    }

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