PHP设计模式之规格模式（Specification）代码实例大全（28）

墨蓝 2022-12-08 13:00 200阅读 0赞

## 目的 ##

构建一个清晰的业务规则规范，其中每条规则都能被针对性地检查。每个规范类中都有一个称为isSatisfiedBy的方法，方法判断给定的规则是否满足规范从而返回 true 或 false。

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## UML图 ##

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## 代码 ##

*  Item.php

<?php
    
    namespace DesignPatterns\Behavioral\Specification;
    
    class Item
    {
        /**
         * @var float
         */
        private $price;
    
        public function __construct(float $price)
        {
            $this->price = $price;
        }
    
        public function getPrice(): float
        {
            return $this->price;
        }
    }

*  SpecificationInterface.php

<?php
    
    namespace DesignPatterns\Behavioral\Specification;
    
    interface SpecificationInterface
    {
        public function isSatisfiedBy(Item $item): bool;
    }

*  OrSpecification.php

<?php
    
    namespace DesignPatterns\Behavioral\Specification;
    
    class OrSpecification implements SpecificationInterface
    {
        /**
         * @var SpecificationInterface[]
         */
        private $specifications;
    
        /**
         * @param SpecificationInterface[] ...$specifications
         */
        public function __construct(SpecificationInterface ...$specifications)
        {
            $this->specifications = $specifications;
        }
    
        /**
         * 如果有一条规则符合条件，返回 true，否则返回 false
         */
        public function isSatisfiedBy(Item $item): bool
        {
            foreach ($this->specifications as $specification) {
                if ($specification->isSatisfiedBy($item)) {
                    return true;
                }
            }
            return false;
        }
    }

*  PriceSpecification.php

<?php
    
    namespace DesignPatterns\Behavioral\Specification;
    
    class PriceSpecification implements SpecificationInterface
    {
        /**
         * @var float|null
         */
        private $maxPrice;
    
        /**
         * @var float|null
         */
        private $minPrice;
    
        /**
         * @param float $minPrice
         * @param float $maxPrice
         */
        public function __construct($minPrice, $maxPrice)
        {
            $this->minPrice = $minPrice;
            $this->maxPrice = $maxPrice;
        }
    
        public function isSatisfiedBy(Item $item): bool
        {
            if ($this->maxPrice !== null && $item->getPrice() > $this->maxPrice) {
                return false;
            }
    
            if ($this->minPrice !== null && $item->getPrice() < $this->minPrice) {
                return false;
            }
    
            return true;
        }
    }

*  AndSpecification.php

<?php
    
    namespace DesignPatterns\Behavioral\Specification;
    
    class AndSpecification implements SpecificationInterface
    {
        /**
         * @var SpecificationInterface[]
         */
        private $specifications;
    
        /**
         * @param SpecificationInterface[] ...$specifications
         */
        public function __construct(SpecificationInterface ...$specifications)
        {
            $this->specifications = $specifications;
        }
    
        /**
         * 如果有一条规则不符合条件，返回 false，否则返回 true
         */
        public function isSatisfiedBy(Item $item): bool
        {
            foreach ($this->specifications as $specification) {
                if (!$specification->isSatisfiedBy($item)) {
                    return false;
                }
            }
    
            return true;
        }
    }

*  NotSpecification.php

<?php
    
    namespace DesignPatterns\Behavioral\Specification;
    
    class NotSpecification implements SpecificationInterface
    {
        /**
         * @var SpecificationInterface
         */
        private $specification;
    
        public function __construct(SpecificationInterface $specification)
        {
            $this->specification = $specification;
        }
    
        public function isSatisfiedBy(Item $item): bool
        {
            return !$this->specification->isSatisfiedBy($item);
        }
    }

## 测试 ##

*  Tests/SpecificationTest.php

<?php
    
    namespace DesignPatterns\Behavioral\Specification\Tests;
    
    use DesignPatterns\Behavioral\Specification\Item;
    use DesignPatterns\Behavioral\Specification\NotSpecification;
    use DesignPatterns\Behavioral\Specification\OrSpecification;
    use DesignPatterns\Behavioral\Specification\AndSpecification;
    use DesignPatterns\Behavioral\Specification\PriceSpecification;
    use PHPUnit\Framework\TestCase;
    
    class SpecificationTest extends TestCase
    {
        public function testCanOr()
        {
            $spec1 = new PriceSpecification(50, 99);
            $spec2 = new PriceSpecification(101, 200);
    
            $orSpec = new OrSpecification($spec1, $spec2);
    
            $this->assertFalse($orSpec->isSatisfiedBy(new Item(100)));
            $this->assertTrue($orSpec->isSatisfiedBy(new Item(51)));
            $this->assertTrue($orSpec->isSatisfiedBy(new Item(150)));
        }
    
        public function testCanAnd()
        {
            $spec1 = new PriceSpecification(50, 100);
            $spec2 = new PriceSpecification(80, 200);
    
            $andSpec = new AndSpecification($spec1, $spec2);
    
            $this->assertFalse($andSpec->isSatisfiedBy(new Item(150)));
            $this->assertFalse($andSpec->isSatisfiedBy(new Item(1)));
            $this->assertFalse($andSpec->isSatisfiedBy(new Item(51)));
            $this->assertTrue($andSpec->isSatisfiedBy(new Item(100)));
        }
    
        public function testCanNot()
        {
            $spec1 = new PriceSpecification(50, 100);
            $notSpec = new NotSpecification($spec1);
    
            $this->assertTrue($notSpec->isSatisfiedBy(new Item(150)));
            $this->assertFalse($notSpec->isSatisfiedBy(new Item(50)));
        }
    }

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