Zend Framework动作助手(Zend_Controller_Action_Helper)用法详解

本文实例讲述了Zend Framework动作助手(Zend_Controller_Action_Helper)用法。分享给大家供大家参考，具体如下：

通过助手模式，可以把一些经常使用的功能模块做封装，从而在可以在需要的地方灵活使用，主要是在action使用。

Zend Framework中有两种助手，动作助手(Zend_Controller_Action_Helper)和试图助手(Zend_View_Helper)。

动作助手可以向任何Zend_Controller_Action的衍生动作控制器中，即时的加入功能(runtime and/or on-demand functionality)，以使得增加公共的动作控制器功能时，尽量减少衍生动作控制器类的必要。

动作助手在需要调用时加载，可以在请求的时候(bootstrap)或者动作控制器创建的时候(init())实例化。

涉及到的相关文件

在/library/Zend/Controller/Action/中

│  Exception.php│  HelperBroker.php│  Interface.php│├─Helper│  │  Abstract.php│  │  ActionStack.php│  │  AjaxContext.php│  │  AutoCompleteDojo.php│  │  AutoCompleteScriptaculous.php│  │  Cache.php│  │  ContextSwitch.php│  │  FlashMessenger.php│  │  Json.php│  │  Redirector.php│  │  Url.php│  │  ViewRenderer.php│  ││  └─AutoComplete│          Abstract.php│└─HelperBroker       PriorityStack.php

常见的动作助手有：

FlashMessenger 用来处理Flash Messenger会话；Json 用来解码和发送 JSON 响应；Url  用于创建Urls；Redirector 提供另一种实现方式，帮助程序重定向到内部或者外部页面；ViewRenderer 自动的完成在控制器内建立视图对象并渲染视图的过程；AutoComplete 自动响应 AJAX 的自动完成；ContextSwitch 和 AjaxContext 为你的动作提供替代响应格式；Cache  实现cache的相关操作；ActionStack 用于操作动作堆栈。

动手的几种实例化使用方式

1.通过Zend_Controller_Action的 $_helper成员的getHelper()方法。直接调用getHelper()，传入助手的名称即可。

$redirector = $this->_helper->getHelper("Redirector");//$redirector->getName();$redirector->gotoSimple("index2");

2.直接通过访问的_helper助手的属性对应的助手对象。

$redirector = $this->_helper->Redirector;

Zend_Controller_Action_HelperBroker

中文名称译作"助手经纪人",顾名思义，是动作助手的中间人。

在动作的实例化使用的方式的第二种方式就是通过Zend_Controller_Action_HelperBroker的魔术方法__get()来实现的。

助手经纪人用于注册助手对象和助手路径以及获取助手等等功能。

Zend_Controller_Action_HelperBroker的实现以及常用方法列表

<?php/** * @see Zend_Controller_Action_HelperBroker_PriorityStack */require_once "Zend/Controller/Action/HelperBroker/PriorityStack.php";/** * @see Zend_Loader */require_once "Zend/Loader.php";/** * @category  Zend * @package  Zend_Controller * @subpackage Zend_Controller_Action * @copyright Copyright (c) 2005-2011 Zend Technologies USA Inc. (http://www.zend.com) * @license  http://framework.zend.com/license/new-bsd   New BSD License */class Zend_Controller_Action_HelperBroker{  /**   * $_actionController - ActionController reference   *   * @var Zend_Controller_Action   */  protected $_actionController;  /**   * @var Zend_Loader_PluginLoader_Interface   */  protected static $_pluginLoader;  /**   * $_helpers - Helper array   *   * @var Zend_Controller_Action_HelperBroker_PriorityStack   */  protected static $_stack = null;  /**   * Set PluginLoader for use with broker   *   * @param Zend_Loader_PluginLoader_Interface $loader   * @return void   */  public static function setPluginLoader($loader)  {    if ((null !== $loader) && (!$loader instanceof Zend_Loader_PluginLoader_Interface)) {      require_once "Zend/Controller/Action/Exception.php";      throw new Zend_Controller_Action_Exception("Invalid plugin loader provided to HelperBroker");    }    self::$_pluginLoader = $loader;  }  /**   * Retrieve PluginLoader   *   * @return Zend_Loader_PluginLoader   */  public static function getPluginLoader()  {    if (null === self::$_pluginLoader) {      require_once "Zend/Loader/PluginLoader.php";      self::$_pluginLoader = new Zend_Loader_PluginLoader(array(        "Zend_Controller_Action_Helper" => "Zend/Controller/Action/Helper/",      ));    }    return self::$_pluginLoader;  }  /**   * addPrefix() - Add repository of helpers by prefix   *   * @param string $prefix   */  static public function addPrefix($prefix)  {    $prefix = rtrim($prefix, "_");    $path  = str_replace("_", DIRECTORY_SEPARATOR, $prefix);    self::getPluginLoader()->addPrefixPath($prefix, $path);  }  /**   * addPath() - Add path to repositories where Action_Helpers could be found.   *   * @param string $path   * @param string $prefix Optional; defaults to "Zend_Controller_Action_Helper"   * @return void   */  static public function addPath($path, $prefix = "Zend_Controller_Action_Helper")  {    self::getPluginLoader()->addPrefixPath($prefix, $path);  }  /**   * addHelper() - Add helper objects   *   * @param Zend_Controller_Action_Helper_Abstract $helper   * @return void   */  static public function addHelper(Zend_Controller_Action_Helper_Abstract $helper)  {    self::getStack()->push($helper);    return;  }  /**   * resetHelpers()   *   * @return void   */  static public function resetHelpers()  {    self::$_stack = null;    return;  }  /**   * Retrieve or initialize a helper statically   *   * Retrieves a helper object statically, loading on-demand if the helper   * does not already exist in the stack. Always returns a helper, unless   * the helper class cannot be found.   *   * @param string $name   * @return Zend_Controller_Action_Helper_Abstract   */  public static function getStaticHelper($name)  {    $name = self::_normalizeHelperName($name);    $stack = self::getStack();    if (!isset($stack->{$name})) {      self::_loadHelper($name);    }    return $stack->{$name};  }  /**   * getExistingHelper() - get helper by name   *   * Static method to retrieve helper object. Only retrieves helpers already   * initialized with the broker (either via addHelper() or on-demand loading   * via getHelper()).   *   * Throws an exception if the referenced helper does not exist in the   * stack; use {@link hasHelper()} to check if the helper is registered   * prior to retrieving it.   *   * @param string $name   * @return Zend_Controller_Action_Helper_Abstract   * @throws Zend_Controller_Action_Exception   */  public static function getExistingHelper($name)  {    $name = self::_normalizeHelperName($name);    $stack = self::getStack();    if (!isset($stack->{$name})) {      require_once "Zend/Controller/Action/Exception.php";      throw new Zend_Controller_Action_Exception("Action helper "" . $name . "" has not been registered with the helper broker");    }    return $stack->{$name};  }  /**   * Return all registered helpers as helper => object pairs   *   * @return array   */  public static function getExistingHelpers()  {    return self::getStack()->getHelpersByName();  }  /**   * Is a particular helper loaded in the broker?   *   * @param string $name   * @return boolean   */  public static function hasHelper($name)  {    $name = self::_normalizeHelperName($name);    return isset(self::getStack()->{$name});  }  /**   * Remove a particular helper from the broker   *   * @param string $name   * @return boolean   */  public static function removeHelper($name)  {    $name = self::_normalizeHelperName($name);    $stack = self::getStack();    if (isset($stack->{$name})) {      unset($stack->{$name});    }    return false;  }  /**   * Lazy load the priority stack and return it   *   * @return Zend_Controller_Action_HelperBroker_PriorityStack   */  public static function getStack()  {    if (self::$_stack == null) {      self::$_stack = new Zend_Controller_Action_HelperBroker_PriorityStack();    }    return self::$_stack;  }  /**   * Constructor   *   * @param Zend_Controller_Action $actionController   * @return void   */  public function __construct(Zend_Controller_Action $actionController)  {    $this->_actionController = $actionController;    foreach (self::getStack() as $helper) {      $helper->setActionController($actionController);      $helper->init();    }  }  /**   * notifyPreDispatch() - called by action controller dispatch method   *   * @return void   */  public function notifyPreDispatch()  {    foreach (self::getStack() as $helper) {      $helper->preDispatch();    }  }  /**   * notifyPostDispatch() - called by action controller dispatch method   *   * @return void   */  public function notifyPostDispatch()  {    foreach (self::getStack() as $helper) {      $helper->postDispatch();    }  }  /**   * getHelper() - get helper by name   *   * @param string $name   * @return Zend_Controller_Action_Helper_Abstract   */  public function getHelper($name)  {    $name = self::_normalizeHelperName($name);    $stack = self::getStack();    if (!isset($stack->{$name})) {      self::_loadHelper($name);    }    $helper = $stack->{$name};    $initialize = false;    if (null === ($actionController = $helper->getActionController())) {      $initialize = true;    } elseif ($actionController !== $this->_actionController) {      $initialize = true;    }    if ($initialize) {      $helper->setActionController($this->_actionController)          ->init();    }    return $helper;  }  /**   * Method overloading   *   * @param string $method   * @param array $args   * @return mixed   * @throws Zend_Controller_Action_Exception if helper does not have a direct() method   */  public function __call($method, $args)  {    $helper = $this->getHelper($method);    if (!method_exists($helper, "direct")) {      require_once "Zend/Controller/Action/Exception.php";      throw new Zend_Controller_Action_Exception("Helper "" . $method . "" does not support overloading via direct()");    }    return call_user_func_array(array($helper, "direct"), $args);  }  /**   * Retrieve helper by name as object property   *   * @param string $name   * @return Zend_Controller_Action_Helper_Abstract   */  public function __get($name)  {    return $this->getHelper($name);  }  /**   * Normalize helper name for lookups   *   * @param string $name   * @return string   */  protected static function _normalizeHelperName($name)  {    if (strpos($name, "_") !== false) {      $name = str_replace(" ", "", ucwords(str_replace("_", " ", $name)));    }    return ucfirst($name);  }  /**   * Load a helper   *   * @param string $name   * @return void   */  protected static function _loadHelper($name)  {    try {      $class = self::getPluginLoader()->load($name);    } catch (Zend_Loader_PluginLoader_Exception $e) {      require_once "Zend/Controller/Action/Exception.php";      throw new Zend_Controller_Action_Exception("Action Helper by name " . $name . " not found", 0, $e);    }    $helper = new $class();    if (!$helper instanceof Zend_Controller_Action_Helper_Abstract) {      require_once "Zend/Controller/Action/Exception.php";      throw new Zend_Controller_Action_Exception("Helper name " . $name . " -> class " . $class . " is not of type Zend_Controller_Action_Helper_Abstract");    }    self::getStack()->push($helper);  }}

助手经纪人的常见用法：

一、注册一个助手

1.

Zend_Controller_Action_HelperBroker::addHelper($helper);

2.通过addPrefix()方法带有一个类前缀参数，用来加入自定义助手类的路径。要求前缀遵循Zend Framework的类命名惯例。

// Add helpers prefixed with My_Action_Helpers in My/Action/Helpers/Zend_Controller_Action_HelperBroker::addPrefix("My_Action_Helpers");

3.使用addPath()方法第一个参数为一个目录，第二个为类前缀(默认为"Zend_Controller_Action_Helper")。

用来将自己的类前缀映射到指定的目录。

// Add helpers prefixed with Helper in Plugins/Helpers/Zend_Controller_Action_HelperBroker::addPath("./Plugins/Helpers",                       "Helper");

二、判读助手是否存在

使用hasHelper($name)方法来判定助手经纪人中是否存在某助手，$name是助手的短名称（去掉前缀的）：

// Check if "redirector" helper is registered with the broker:if (Zend_Controller_Action_HelperBroker::hasHelper("redirector")) {  echo "Redirector helper registered";}

从助手经纪人中获取助手有两个静态方法：getExistingHelper() 和 getStaticHelper() 。getExistingHelper()将获取助手仅当它以前调用过或者显性地通过助手经纪人注册过，否则就抛出一个异常。getStaticHelper() 的做法和getExistingHelper()一样，但如果还没有注册助手堆栈，它将尝试初始化助手，为获取你要配置的的助手，getStaticHelper()是一个好的选择。

两个方法都带一个参数，$name，它是助手的短名称（去掉前缀）。

// Check if "redirector" helper is registered with the broker, and fetch:if (Zend_Controller_Action_HelperBroker::hasHelper("redirector")) {  $redirector =    Zend_Controller_Action_HelperBroker::getExistingHelper("redirector");}// Or, simply retrieve it, not worrying about whether or not it was// previously registered:$redirector =  Zend_Controller_Action_HelperBroker::getStaticHelper("redirector");}

三、removeHelper($name)删除助手经纪人中的某个助手，$name是助手的短名称。

// Conditionally remove the "redirector" helper from the broker:if (Zend_Controller_Action_HelperBroker::hasHelper("redirector")) {  Zend_Controller_Action_HelperBroker::removeHelper("redirector")}

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