php工厂设计模式

class DbFactory {
    private $errmsg = '未找到类文件';
    static function factory($className){
        $className = strtoupper(substr($className,0,1)).substr($className, 1);
        if(include_once($className.'.php')){
            return new $className;
        }
        else{
            throw new Exception($this->errmsg);
        }
    }
}
DbFactory::factory('cars');
DbFactory::factory('animal');

Cars.php


<?php
class Cars{
    function __construct(){
        echo "汽车类";
    }
}

Animal.php

<?php
class Animal{
    function __construct(){
        echo '动物世界！';
    }
}