策略模式

定义：将一组特定的行为和算法封装成类，以适应某些特定的上下文环境，使用策略模式可以实现Ioc,依赖倒置、控制反转

实际应用举例：假如一个电商网站系统，针对男性女性的用户要各自跳转到不同商品类目，并且所有广告位展示不同的广告（分支逻辑）

class Page
{
    protected $strategy;
    function index()
    {
        echo "AD:";
        $this->strategy->showAd();
        echo "<br/>";

        echo "category:";
        $this->strategy->showCategory();
        echo "<br/>";

    }

    function setStrategy(\IMooc\UserStrategy $strategy)
    {
        $this->strategy = $strategy;
    }
}

$page = new Page;
if (isset($_GET['female']))
{
    $strategy = new \IMooc\FemaleUserStrategy();
}
else
{
    $strategy = new \IMooc\MaleUserStrategy();
}
$page->setStrategy($strategy);
$page->index();

<?php
namespace IMooc;

interface UserStrategy
{
    function showAd();
    function showCategory();
}

<?php
namespace IMooc;


class FemaleUserStrategy implements UserStrategy
{

    function showAd()
    {
        echo "2016新款女装";
    }

    function showCategory()
    {
        echo "女装";
    }
}

<?php
namespace IMooc;


class MaleUserStrategy implements UserStrategy
{

    function showAd()
    {
        echo "IPhone6";
    }

    function showCategory()
    {
        echo "电子产品";
    }
}

来自为知笔记(Wiz)