设计模式之策略模式

<?php
interface IStrategy
{
    function filter( $record );
}//定义一个接口

class FindNameWithA implements IStrategy//实现接口
{
    public function filter($record) 
    {
        $record = strtolower($record);//变换成小写
        if (strpos($record, ‘a‘)!==false) {//返回record中a出现在第几个，这里是看是否有a这个字母
            return true;
        }
        return false;
    }
}
class FindAfterStrategy implements IStrategy
{
    private $_name;

    public function __construct( $name )
    {
        $this->_name = $name;
    }

    public function filter( $record )
    {
        return strcmp( $this->_name, $record ) <= 0;//比较两个字符串
    }
}

class RandomStrategy implements IStrategy
{
    public function filter( $record )
    {
        return rand( 0, 1 ) >= 0.5;//生成随机数
    }
}

class UserList
{
    private $_list = array();

    public function __construct( $names )
    {
        if ( $names != null )
        {
            foreach( $names as $name )
            {
                $this->_list []= $name;
            }
        }
    }

    public function add( $name )
    {
        $this->_list []= $name;
    }

    public function find( $filter )
    {
        $recs = array();
        foreach( $this->_list as $user ) {
            if ( $filter->filter( $user ) ) {
                $recs []= $user;
            }
        }
        return $recs;
    }
}

$ul = new UserList(array("Andy", "Jack", "Lori", "Megan"));
$f1 = $ul->find(new FindAfterStrategy("J"));
print_r($f1);

$f2 = $ul->find(new RandomStrategy());
print_r($f2);

$f3 = $ul->find(new FindNameWithA());
print_r($f3);