策略模式是一种行为设计模式， 它能让你定义一系列算法， 并将每种算法分别放入独立的类中，将行为转换为对象，以使算法的对象能够相互替换。

<?php

//定义算法及抽象实现
interface strategy
{
    function algorithmInterface();
}

class concreteStrategyA implements strategy
{
    function algorithmInterface()
    {
        echo '算法A';
    }
}

class concreteStrategyB implements strategy
{
    function algorithmInterface()
    {
        echo '算法B';
    }
}

//定义上下文执行环境
class context
{
    private $strategy;

    function __construct(strategy $s)
    {
        $this->strategy = $s;
    }

    function contextInterface()
    {
        $this->strategy->algorithmInterface();
    }
}

//客户端调用不同算法
$strategyA = new concreteStrategyA();
$context = new context($strategyA);
$context->contextInterface();   //算法A

$strategyB = new concreteStrategyB();
$context = new context($strategyB);
$context->contextInterface();   //算法B

 

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