PHP 设计模式系列之 specification规格模式_php实例
1、模式定义
规格模式是组合模式的一种扩展,在框架性开发中使用较多(项目级开发很少使用),这里做一个简单的介绍。
规格模式(Specification)可以认为是组合模式的一种扩展。有时项目中某些条件决定了业务逻辑,这些条件就可以抽离出来以某种关系(与、或、非)进行组合,从而灵活地对业务逻辑进行定制。另外,在查询、过滤等应用场合中,通过预定义多个条件,然后使用这些条件的组合来处理查询或过滤,而不是使用逻辑判断语句来处理,可以简化整个实现逻辑。
这里的每个条件就是一个规格,多个规格/条件通过串联的方式以某种逻辑关系形成一个组合式的规格。
2、UML类图
3、示例代码
Item.php
<?php namespace DesignPatterns\Behavioral\Specification; class Item { protected $price; /** * An item must have a price * * @param int $price */ public function __construct($price) { $this->price = $price; } /** * Get the items price * * @return int */ public function getPrice() { return $this->price; } }
SpecificationInterface.php
<?php namespace DesignPatterns\Behavioral\Specification; /** * 规格接口 */ interface SpecificationInterface { /** * 判断对象是否满足规格 * * @param Item $item * * @return bool */ public function isSatisfiedBy(Item $item); /** * 创建一个逻辑与规格(AND) * * @param SpecificationInterface $spec */ public function plus(SpecificationInterface $spec); /** * 创建一个逻辑或规格(OR) * * @param SpecificationInterface $spec */ public function either(SpecificationInterface $spec); /** * 创建一个逻辑非规格(NOT) */ public function not(); }
AbstractSpecification.php
<?php namespace DesignPatterns\Behavioral\Specification; /** * 规格抽象类 */ abstract class AbstractSpecification implements SpecificationInterface { /** * 检查给定Item是否满足所有规则 * * @param Item $item * * @return bool */ abstract public function isSatisfiedBy(Item $item); /** * 创建一个新的逻辑与规格(AND) * * @param SpecificationInterface $spec * * @return SpecificationInterface */ public function plus(SpecificationInterface $spec) { return new Plus($this, $spec); } /** * 创建一个新的逻辑或组合规格(OR) * * @param SpecificationInterface $spec * * @return SpecificationInterface */ public function either(SpecificationInterface $spec) { return new Either($this, $spec); } /** * 创建一个新的逻辑非规格(NOT) * * @return SpecificationInterface */ public function not() { return new Not($this); } }
Plus.php
<?php namespace DesignPatterns\Behavioral\Specification; /** * 逻辑与规格(AND) */ class Plus extends AbstractSpecification { protected $left; protected $right; /** * 在构造函数中传入两种规格 * * @param SpecificationInterface $left * @param SpecificationInterface $right */ public function __construct(SpecificationInterface $left, SpecificationInterface $right) { $this->left = $left; $this->right = $right; } /** * 返回两种规格的逻辑与评估 * * @param Item $item * * @return bool */ public function isSatisfiedBy(Item $item) { return $this->left->isSatisfiedBy($item) && $this->right->isSatisfiedBy($item); } }
Either.php
<?php namespace DesignPatterns\Behavioral\Specification; /** * 逻辑或规格 */ class Either extends AbstractSpecification { protected $left; protected $right; /** * 两种规格的组合 * * @param SpecificationInterface $left * @param SpecificationInterface $right */ public function __construct(SpecificationInterface $left, SpecificationInterface $right) { $this->left = $left; $this->right = $right; } /** * 返回两种规格的逻辑或评估 * * @param Item $item * * @return bool */ public function isSatisfiedBy(Item $item) { return $this->left->isSatisfiedBy($item) || $this->right->isSatisfiedBy($item); } }
Not.php
<?php namespace DesignPatterns\Behavioral\Specification; /** * 逻辑非规格 */ class Not extends AbstractSpecification { protected $spec; /** * 在构造函数中传入指定规格 * * @param SpecificationInterface $spec */ public function __construct(SpecificationInterface $spec) { $this->spec = $spec; } /** * 返回规格的相反结果 * * @param Item $item * * @return bool */ public function isSatisfiedBy(Item $item) { return !$this->spec->isSatisfiedBy($item); } }
PriceSpecification.php
<?php namespace DesignPatterns\Behavioral\Specification; /** * 判断给定Item的价格是否介于最小值和最大值之间的规格 */ class PriceSpecification extends AbstractSpecification { protected $maxPrice; protected $minPrice; /** * 设置最大值 * * @param int $maxPrice */ public function setMaxPrice($maxPrice) { $this->maxPrice = $maxPrice; } /** * 设置最小值 * * @param int $minPrice */ public function setMinPrice($minPrice) { $this->minPrice = $minPrice; } /** * 判断给定Item的定价是否在最小值和最大值之间 * * @param Item $item * * @return bool */ public function isSatisfiedBy(Item $item) { if (!empty($this->maxPrice) && $item->getPrice() > $this->maxPrice) { return false; } if (!empty($this->minPrice) && $item->getPrice() < $this->minPrice) { return false; } return true; } }
4、测试代码
Tests/SpecificationTest.php
<?php namespace DesignPatterns\Behavioral\Specification\Tests; use DesignPatterns\Behavioral\Specification\PriceSpecification; use DesignPatterns\Behavioral\Specification\Item; /** * SpecificationTest 用于测试规格模式 */ class SpecificationTest extends \PHPUnit_Framework_TestCase { public function testSimpleSpecification() { $item = new Item(100); $spec = new PriceSpecification(); $this->assertTrue($spec->isSatisfiedBy($item)); $spec->setMaxPrice(50); $this->assertFalse($spec->isSatisfiedBy($item)); $spec->setMaxPrice(150); $this->assertTrue($spec->isSatisfiedBy($item)); $spec->setMinPrice(101); $this->assertFalse($spec->isSatisfiedBy($item)); $spec->setMinPrice(100); $this->assertTrue($spec->isSatisfiedBy($item)); } public function testNotSpecification() { $item = new Item(100); $spec = new PriceSpecification(); $not = $spec->not(); $this->assertFalse($not->isSatisfiedBy($item)); $spec->setMaxPrice(50); $this->assertTrue($not->isSatisfiedBy($item)); $spec->setMaxPrice(150); $this->assertFalse($not->isSatisfiedBy($item)); $spec->setMinPrice(101); $this->assertTrue($not->isSatisfiedBy($item)); $spec->setMinPrice(100); $this->assertFalse($not->isSatisfiedBy($item)); } public function testPlusSpecification() { $spec1 = new PriceSpecification(); $spec2 = new PriceSpecification(); $plus = $spec1->plus($spec2); $item = new Item(100); $this->assertTrue($plus->isSatisfiedBy($item)); $spec1->setMaxPrice(150); $spec2->setMinPrice(50); $this->assertTrue($plus->isSatisfiedBy($item)); $spec1->setMaxPrice(150); $spec2->setMinPrice(101); $this->assertFalse($plus->isSatisfiedBy($item)); $spec1->setMaxPrice(99); $spec2->setMinPrice(50); $this->assertFalse($plus->isSatisfiedBy($item)); } public function testEitherSpecification() { $spec1 = new PriceSpecification(); $spec2 = new PriceSpecification(); $either = $spec1->either($spec2); $item = new Item(100); $this->assertTrue($either->isSatisfiedBy($item)); $spec1->setMaxPrice(150); $spec2->setMaxPrice(150); $this->assertTrue($either->isSatisfiedBy($item)); $spec1->setMaxPrice(150); $spec2->setMaxPrice(0); $this->assertTrue($either->isSatisfiedBy($item)); $spec1->setMaxPrice(0); $spec2->setMaxPrice(150); $this->assertTrue($either->isSatisfiedBy($item)); $spec1->setMaxPrice(99); $spec2->setMaxPrice(99); $this->assertFalse($either->isSatisfiedBy($item)); } }
以上内容是脚本之家小编给大家分享的PHP 设计模式系列之 specification规格模式,希望本文分享能够帮助大家。

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