php面向对象设计（14PHP设计模式系列）
php面向对象设计（14PHP设计模式系列）<?php namespace DesignPatterns\Structural\Decorator; /** * RenderInJson类 */ class RenderInJson extends Decorator { /** * render data as JSON * * @return mixed|string */ public function renderData() { $output = $this->wrapped->renderData(); return json_encode($output); } } 4、测试代码Tests/DecoratorTest.php<?php namespace DesignPatterns\Structural\Decorator; /** * RenderInXml类
1、模式定义装饰器模式能够从一个对象的外部动态地给对象添加功能。
通常给对象添加功能，要么直接修改对象添加相应的功能，要么派生对应的子类来扩展，抑或是使用对象组合的方式。显然，直接修改对应的类这种方式并不可取。在面向对象的设计中，我们也应该尽量使用对象组合，而不是对象继承来扩展和复用功能。装饰器模式就是基于对象组合的方式，可以很灵活的给对象添加所需要的功能。装饰器模式的本质就是动态组合。动态是手段，组合才是目的。
常见的使用示例：Web服务层 —— 为 REST 服务提供 JSON 和 XML 装饰器。
2、UML类图
RendererInterface.php
<?php namespace DesignPatterns\Structural\Decorator; /** * RendererInterface接口 */ interface RendererInterface { /** * render data * * @return mixed */ public function renderData(); }
Webservice.php
<?php namespace DesignPatterns\Structural\Decorator; /** * Webservice类 */ class Webservice implements RendererInterface { /** * @var mixed */ protected $data; /** * @param mixed $data */ public function __construct($data) { $this->data = $data; } /** * @return string */ public function renderData() { return $this->data; } }
Decorator.php
<?php namespace DesignPatterns\Structural\Decorator; /** * 装饰器必须实现 RendererInterface 接口 这是装饰器模式的主要特点， * 否则的话就不是装饰器而只是个包裹类 */ /** * Decorator类 */ abstract class Decorator implements RendererInterface { /** * @var RendererInterface */ protected $wrapped; /** * 必须类型声明装饰组件以便在子类中可以调用renderData()方法 * * @param RendererInterface $wrappable */ public function __construct(RendererInterface $wrappable) { $this->wrapped = $wrappable; } }
RenderInXml.php
<?php namespace DesignPatterns\Structural\Decorator; /** * RenderInXml类 */ class RenderInXml extends Decorator { /** * render data as XML * * @return mixed|string */ public function renderData() { $output = $this->wrapped->renderData(); // do some fancy conversion to xml from array ... $doc = new \DOMDocument(); foreach ($output as $key => $val) { $doc->appendChild($doc->createElement($key $val)); } return $doc->saveXML(); } }
RenderInJson.php
<?php namespace DesignPatterns\Structural\Decorator; /** * RenderInJson类 */ class RenderInJson extends Decorator { /** * render data as JSON * * @return mixed|string */ public function renderData() { $output = $this->wrapped->renderData(); return json_encode($output); } } 4、测试代码
Tests/DecoratorTest.php
<?php namespace DesignPatterns\Structural\Decorator\Tests; use DesignPatterns\Structural\Decorator; /** * DecoratorTest 用于测试装饰器模式 */ class DecoratorTest extends \PHPUnit_Framework_TestCase { protected $service; protected function setUp() { $this->service = new Decorator\Webservice(array('foo' => 'bar')); } public function testJsonDecorator() { // Wrap service with a JSON decorator for renderers $service = new Decorator\RenderInJson($this->service); // Our Renderer will now output JSON instead of an array $this->assertEquals('{"foo":"bar"}' $service->renderData()); } public function testXmlDecorator() { // Wrap service with a XML decorator for renderers $service = new Decorator\RenderInXml($this->service); // Our Renderer will now output XML instead of an array $xml = '<?xml version="1.0"?><foo>bar</foo>'; $this->assertXmlStringEqualsXmlString($xml $service->renderData()); } /** * The first key-point of this pattern : */ public function testDecoratorMustImplementsRenderer() { $className = 'DesignPatterns\Structural\Decorator\Decorator'; $interfaceName = 'DesignPatterns\Structural\Decorator\RendererInterface'; $this->assertTrue(is_subclass_of($className $interfaceName)); } /** * Second key-point of this pattern : the decorator is type-hinted * * @expectedException \PHPUnit_Framework_Error */ public function testDecoratorTypeHinted() { if (version_compare(PHP_VERSION '7' '>=')) { throw new \PHPUnit_Framework_Error('Skip test for PHP 7' 0 __FILE__ __LINE__); } $this->getMockForAbstractClass('DesignPatterns\Structural\Decorator\Decorator' array(new \stdClass())); } /** * Second key-point of this pattern : the decorator is type-hinted * * @requires PHP 7 * @expectedException TypeError */ public function testDecoratorTypeHintedForPhp7() { $this->getMockForAbstractClass('DesignPatterns\Structural\Decorator\Decorator' array(new \stdClass())); } /** * The decorator implements and wraps the same interface */ public function testDecoratorOnlyAcceptRenderer() { $mock = $this->getMock('DesignPatterns\Structural\Decorator\RendererInterface'); $dec = $this->getMockForAbstractClass('DesignPatterns\Structural\Decorator\Decorator' array($mock)); $this->assertNotNull($dec); } }
