最近在看《大话设计模式》，打算写个系列笔记，在帮助到新手的同时可以巩固自己的知识，希望能坚持下去吧。

工厂模式的核心是创建一个工厂类，通过这个类创建所需要的对象，这样做的好处是增加了代码的可拓展性，降低了耦合度，容易修改，并且易于复用。

<?php

interface Operation{
    public function getRes($numA,$numB);
}

# 加法类
class OperationAdd implements Operation{
    public function getRes($numA,$numB){
        return $numA + $numB;
    }
}

# 减法类
class OperationSub implements Operation{
    public function getRes($numA,$numB){
        return $numA - $numB;
    }
}

# 乘法类
class OperationMul implements Operation{
    public function getRes($numA,$numB){
        return $numA * $numB;
    }
}

# 除法类
class OperationDiv implements Operation{
    public function getRes($numA,$numB){
        try {
            if ($numB == 0) {
                throw new Exception("除数不能为0", 1);
            }else{
                return $numA / $numB;
            }
        } catch (Exception $e) {
            echo "错误信息：".$e->getMessage();
        }
        
    }
}

class OperationFactory{
    public static function createOperate($operate){
        switch ($operate) {
            case '+':
                $oper = new OperationAdd();
                break;
            case '-':
                $oper = new OperationSub();
                break;
            case '*':
                $oper = new OperationMul();
                break;
            case '/':
                $oper = new OperationDiv();
                break;
        }
        return $oper;
    }
}

class Client{
    public function main(){
        $oper = OperationFactory::createOperate('+');
        $res = $oper->getRes(1,2);
        echo $res;
    }
}

$client = new Client();
$client->main();