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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