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')
}

更多关于zend相关内容感兴趣的读者可查看本站专题：《zend framework框架入门教程》、《php优秀开发框架总结》、《yii框架入门及常用技巧总结》、《thinkphp入门教程》、《php面向对象程序设计入门教程》、《php+mysql数据库操作入门教程》及《php常见数据库操作技巧汇总》

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