在策略模式中设置策略

Question

我可能做错了，因为我无法确定在执行战略模式时使用哪种策略的可靠方法。我不太喜欢“静态”地写，也许还有另外一种方法。

背景：，我已经完成了两个(2)实现(soap + http)来传送提供者，以便为用户输入的任何前端检索跟踪和跟踪信息。它们都遵循一个接口，这样我就知道哪些函数是可用的，哪些函数应该可用(PHP :3)。我缩短了下面的类名，因为这是Magento，类名非常长。

流：客户在表单中输入跟踪号码并提交。请求发送给控制器，控制器初始化Service类的一个实例，通过。$ service ->setOutput(' tracking/service_gls ') --注意tracking/service_gls只是直接映射到服务类(Magento )，$ $service->getDeliveryInformation($number)被调用(我们知道这是因为接口而存在的)，整个$service对象返回到视图并显示数据。

我的挑战：，我使用一个开关大小写来设置tracking/service_gls和tracking/service_服务，然后调用getDeliveryInformation()。这是正确的做法吗？我觉得如果有人想要连接另一个运输供应商，这是有点太静态和难以维护。他们必须输入控制器并手动将另一个条目添加到开关情况中，在类中的200行的某个函数中。

控制器的外观示例：

public function getDeliveryInformationAction()
{
    $id = $this->getRequest()->getParam('id', false);
    if ($id && $this->getRequest()->isAjax())
    {
        // SO note: service parameter is just two radio buttons with values "gls", "otherservice"
        $serviceType = $this->getRequest()->getParam('service', false);

        try
        {
            // SO note: same as doing new Class()
            $service = Mage::getModel('tracking/service');

            switch ($serviceType)
            {
                case 'gls':
                $service->setOutput('tracking/service_gls');
                break;

                case 'other':
                $service->setOutput('tracking/service_other');
                break;
            }

            $shipment = $service->getDeliveryInformation($id);

            $output = // .. create block that contains the view, $output will contain the shipment data; this is returned to the ajax request.
        }
        catch (Exception_RequestError $e)
        {
            ..
        }

        // finally
        $this->getResponse()->setHeader('content-type', 'text/html', true);
        $this->getResponse()->setBody($output);
    }
}

代码已经被缩短了一点，因为有更多的功能，但并不重要。

接口两个运输提供程序模型正在实现

interface Output
{
    /* Requests delivery information for the specified tracking number */
    public function getDeliveryInformation($number);

    /**
    * Returns acceptor name
    * @return string
    */
    public function getAcceptorName();
}

服务类处理来自运输模型的请求数据

class Service
{
    protected $output;


    /**
     * Sets the output model to use
     * @param string $outputType
     */
    public function setOutput($outputModel)
    {
        // SO note: same as doing new Class()
        // Magento people note: getModel() works fine tho.. ;-)
        $modelInstance = Mage::app()->getConfig()->getModelInstance($outputModel);
        $this->output = $modelInstance;
    }

    /**
     * Returns delivery information for the specified tracking number
     * @param string $number
     * @return instance of output class
     */
    public function getDeliveryInformation($number)
    {
        // SO note: This makes the shipping class request
        // information and set data internally on the object
        $this->output->getDeliveryInformation($number);
        return $this->output;
    }
}

传送类的示例；在本例中有两个

class Service_Gls implements Output
{
    const SERVICE_NAME = 'GLS';
    const SERVICE_URL = 'http://www.gls-group.eu/276-I-PORTAL-WEBSERVICE/services/Tracking/wsdl/Tracking.wsdl';

    protected $locale = 'da_DK';


    /* Class constructor */
    public function __construct() { }

    /**
     * Requests delivery information for the specified tracking number
     * @param mixed $number
     */
    public function getDeliveryInformation($number)
    {
        $this->_getDeliveryInformation($number);
    }

    /**
     * Requests and sets information for the specified tracking number
     * @param mixed $number
     */
    private function _getDeliveryInformation($number)
    {
        // SO note: Extending from Varien_Object has magic __get, __set .. hence why there is no getData() function in this class.
        if (!count($this->getData()))
        {
            $client = new SoapClient($url);
            $client->GetTuDetail($reference));

            .. set data
        }
    }

    /**
     * Returns acceptor name
     * @return string
     */
    public function getAcceptorName()
    {
        $signature = $this->getSignature();
        return (isset($signature)) ? $this->getSignature() : false;
    }

    /**
     * Returns the name of the current service
     * @return string
     */
    public function __toString()
    {
        return self::SERVICE_NAME;
    }
}

控制器

class AjaxController extends Mage_Core_Controller_Front_Action
{
    public function getDeliveryInformationAction()
    {
        $id = $this->getRequest()->getParam('id', false);
        if ($id && $this->getRequest()->isAjax())
        {
            // SO note: service parameter is just two radio buttons with values "gls", "otherservice"
            $serviceType = $this->getRequest()->getParam('service', false);
            try
            {
                $service = Mage::getModel('tracking/service');

                switch ($serviceType)
                {
                    case 'gls':
                    $service->setOutput('tracking/service_gls');
                    break;

                    case 'other':
                    $service->setOutput('tracking/service_other');
                    break;
                }

                $shipment = $service->getDeliveryInformation($id);

                $output = // .. create block that contains the view, $output will contain the shipment data; this is returned to the ajax request.
            }
            catch (Exception_RequestError $e)
            {
                ..
            }

            // finally
            $this->getResponse()->setHeader('content-type', 'text/html', true);
            $this->getResponse()->setBody($output);
        }
    }
}

Answer 1

您可以使用开关或某种字符串连接来返回所需的策略类。

使用策略模式，在运行时选择正确的策略通常是通过StrategyContext模式：patterns/strategy/php完成的。这允许您隔离算法来选择正确的策略，这样它就不会“在类中200行的某个函数中”。

至于设置运行时策略的算法，我个人喜欢类常量，而不是字符串操作等等。既然游戏的目的是找到一个类名来实例化，为什么不只是一个类常量来返回类名呢？

class OutputStrategyContext{
    const SERVICE = 'tracking/service_gls';
    const OTHER = 'tracking/service_other';

    private $strategy;

    public function __construct($serviceType)
    {
        $strategy = constant('self::' . strtoupper($serviceType));
        $modelInstance = Mage::app()->getConfig()->getModelInstance($strategy);
        $this->strategy = $modelInstance;
    }

    public function getStrategy()
    {
        return $this->strategy;
    }
}

轻量级和易于维护的策略类列表位于一个地方。

当然，您可以使整个事物是静态的，或者使用另一个设计模式，比如抽象的工厂方法来区分相同的东西。真的要看你了。

无论如何，在控制器中，它是一个单线线。

class AjaxController extends Mage_Core_Controller_Front_Action
{
    public function getDeliveryInformationAction()
    {
        $id = $this->getRequest()->getParam('id', false);
        if ($id && $this->getRequest()->isAjax())
        {
            // SO note: service parameter is just two radio buttons with values "gls", "otherservice"
            $serviceType = $this->getRequest()->getParam('service', false);
            try
            {
                $service = Mage::getModel('tracking/service');
                $outputModel = new OutputStrategyContext($serviceType)->getStrategy();
                $service->setOutput($outputModel);

                $shipment = $service->getDeliveryInformation($id);

                $output = // .. create block that contains the view, $output will contain the shipment data; this is returned to the ajax request.
            }
            catch (Exception_RequestError $e)
            {
                ..
            }

            // finally
            $this->getResponse()->setHeader('content-type', 'text/html', true);
            $this->getResponse()->setBody($output);
        }
    }
}

当然，您必须修改服务。我还为您的代码修改了上下文类。

class Service
{
    protected $output;


    /**
     * Sets the output model to use
     * @param string $outputType
     */
    public function setOutput($outputModel)
    {
        // SO note: same as doing new Class()
        // Magento people note: getModel() works fine tho.. ;-)
        $this->output = $outputModel;
    }

    /**
     * Returns delivery information for the specified tracking number
     * @param string $number
     * @return instance of output class
     */
    public function getDeliveryInformation($number)
    {
        // SO note: This makes the shipping class request
        // information and set data internally on the object
        $this->output->getDeliveryInformation($number);
        return $this->output;
    }
}