PHP设计模式之策略模式（Strategy）代码实例大全（30）

清疚 2022-12-09 02:50 176阅读 0赞

## 目的 ##

分离「策略」并使他们之间能互相快速切换。此外，这种模式是一种不错的继承替代方案（替代使用扩展抽象类的方式）。

## 例子 ##

*  简化版的的单元测试：例如，在使用文件存储和内存存储之间互相切换
 *  对一个对象列表进行排序，一种按照日期，一种按照 id

## UML图 ##

![20200921164421986.png][]

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## 代码 ##

*  Context.php

<?php
    
    namespace DesignPatterns\Behavioral\Strategy;
    
    class Context
    {
        /**
         * @var ComparatorInterface
         */
        private $comparator;
    
        public function __construct(ComparatorInterface $comparator)
        {
            $this->comparator = $comparator;
        }
    
        public function executeStrategy(array $elements) : array
        {
            uasort($elements, [$this->comparator, 'compare']);
    
            return $elements;
        }
    }

*  ComparatorInterface.php

<?php
    
    namespace DesignPatterns\Behavioral\Strategy;
    
    interface ComparatorInterface
    {
        /**
         * @param mixed $a
         * @param mixed $b
         *
         * @return int
         */
        public function compare($a, $b): int;
    }

*  DateComparator.php

<?php
    
    namespace DesignPatterns\Behavioral\Strategy;
    
    class DateComparator implements ComparatorInterface
    {
        /**
         * @param mixed $a
         * @param mixed $b
         *
         * @return int
         */
        public function compare($a, $b): int
        {
            $aDate = new \DateTime($a['date']);
            $bDate = new \DateTime($b['date']);
    
            return $aDate <=> $bDate;
        }
    }

*  IdComparator.php

<?php
    
    namespace DesignPatterns\Behavioral\Strategy;
    
    class IdComparator implements ComparatorInterface
    {
        /**
         * @param mixed $a
         * @param mixed $b
         *
         * @return int
         */
        public function compare($a, $b): int
        {
            return $a['id'] <=> $b['id'];
        }
    }

##  ##

测试

*  Tests/StrategyTest.php

<?php
    
    namespace DesignPatterns\Behavioral\Strategy\Tests;
    
    use DesignPatterns\Behavioral\Strategy\Context;
    use DesignPatterns\Behavioral\Strategy\DateComparator;
    use DesignPatterns\Behavioral\Strategy\IdComparator;
    use PHPUnit\Framework\TestCase;
    
    class StrategyTest extends TestCase
    {
        public function provideIntegers()
        {
            return [
                [
                    [['id' => 2], ['id' => 1], ['id' => 3]],
                    ['id' => 1],
                ],
                [
                    [['id' => 3], ['id' => 2], ['id' => 1]],
                    ['id' => 1],
                ],
            ];
        }
    
        public function provideDates()
        {
            return [
                [
                    [['date' => '2014-03-03'], ['date' => '2015-03-02'], ['date' => '2013-03-01']],
                    ['date' => '2013-03-01'],
                ],
                [
                    [['date' => '2014-02-03'], ['date' => '2013-02-01'], ['date' => '2015-02-02']],
                    ['date' => '2013-02-01'],
                ],
            ];
        }
    
        /**
         * @dataProvider provideIntegers
         *
         * @param array $collection
         * @param array $expected
         */
        public function testIdComparator($collection, $expected)
        {
            $obj = new Context(new IdComparator());
            $elements = $obj->executeStrategy($collection);
    
            $firstElement = array_shift($elements);
            $this->assertEquals($expected, $firstElement);
        }
    
        /**
         * @dataProvider provideDates
         *
         * @param array $collection
         * @param array $expected
         */
        public function testDateComparator($collection, $expected)
        {
            $obj = new Context(new DateComparator());
            $elements = $obj->executeStrategy($collection);
    
            $firstElement = array_shift($elements);
            $this->assertEquals($expected, $firstElement);
        }
    }

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