简单的工厂模式演示

Question

我正在尝试用PHP创建一个简单的工厂模式演示。我不确定我的代码是否是最佳实践。似乎我有一些重复的代码，但我不确定如何改进它。基本上，我想创建3种类型的帐户(基本，高级和贵宾)。请给我建议。非常感谢。

抽象类

abstract class User {

    function __construct() {
        $this->db= new Database('mysql','localhost','mvcdb','root','');
    }

    abstract function checkUser();

    function showAccountCredit(){
        return $this->credits;
    }
    function getUserName(){
        return $this->username;
    }


}

我有3种不同的用户帐户类型：

基本帐号

class BasicUser extends User {

    function __construct($username) {
        parent::__construct();
        $this->username=$username;
        $this->credit='10';
        $this->accountType='Basic Account';

        $data=$this->checkUser();

        if(!empty($data)){
            echo 'The username: '.$this->username.' already exists<br>';
            return false;
        }

        $array=array('username'=>$this->username, 'password'=>'password','credit'=> $this->credit,'accountType'=>$this->accountType);
        $this->db->insert('user',$array);

    }


     function checkUser(){

        $array=array(':username'=>$this->username);
        $results=$this->db->select('SELECT * FROM USER WHERE username=:username',$array);
        if(!empty($results)){
        $this->credit=$results[0]['credit'];
        $this->accountType=$results[0]['accountType'];
        }

        return $results;

    }

    function showAccountCredit() {
        echo 'Username: '.$this->username.'<br>';
        echo 'Account Credit: '.$this->credit.'<br>';
        echo 'Account Type: '.$this->accountType;
    }

}

高级帐户

class PremiumUser extends User {

    function __construct($username) {
        parent::__construct();
        $this->username=$username;
        $this->credit='100';
        $this->accountType='Premium Account';

        $data=$this->checkUser();

        if(!empty($data)){
            echo 'The username: '.$this->username.' already exists<br>';
            return false;
        }

        $array=array('username'=>$this->username, 'password'=>'password','credit'=> $this-                   >credit,'accountType'=>$this->accountType);
        $this->db->insert('user',$array);

    }


     function checkUser(){

        $array=array(':username'=>$this->username);
        $results=$this->db->select('SELECT * FROM USER WHERE username=:username',$array);
        if(!empty($results)){
        $this->credit=$results[0]['credit'];
        $this->accountType=$results[0]['accountType'];
        }

        return $results;

    }

    function showAccountCredit() {
        echo 'Username: '.$this->username.'<br>';
        echo 'Account Credit: '.$this->credit.'<br>';
        echo 'Account Type: '.$this->accountType.'<br>';
    }

}

VIP帐号：

class VipUser extends User {

    function __construct($username) {
        parent::__construct();
        $this->username=$username;
        $this->credit='1000';
        $this->accountType='VIP Account';

        $data=$this->checkUser();

        if(!empty($data)){
            echo 'The username: '.$this->username.' already exists<br>';
            return false;
        }

        $array=array('username'=>$this->username, 'password'=>'password','credit'=> $this->credit,'accountType'=>$this->accountType);
        $this->db->insert('user',$array);

    }


     function checkUser(){

        $array=array(':username'=>$this->username);
        $results=$this->db->select('SELECT * FROM USER WHERE username=:username',$array);
        if(!empty($results)){
        $this->credit=$results[0]['credit'];
        $this->accountType=$results[0]['accountType'];
        }

        return $results;

    }

    function showAccountCredit() {
        echo 'Username: '.$this->username.'<br>';
        echo 'Account Credit: '.$this->credit.'<br>';
        echo 'Account Type: '.$this->accountType;
    }

}

UserFactory类

class UserFactory {

    static function create($username,$accountType){

        $accountType = strtolower($accountType);

        switch($accountType){
        case 'basic': return new BasicUser($username);
        case 'premium':return new PremiumUser($username);
        case 'vip': return new VipUser($username);
        default :return new BasicUser($username);
        }
    }

index.php

$user1= UserFactory::create('Jerry', 'Vip');
$user1->showAccountCredit();


$user2= UserFactory::create('Bob', 'Basic');
$user2->showAccountCredit();


$user3= UserFactory::create('Betty', 'premium');
$user3->showAccountCredit();

Answer 1

考虑"UserType“的3个不同实现，而不是3个不同的user实现。分离职责并将对象组合在一起。这是另一种运行中的模式，称为策略。

function showAccountCredit(){
  return $this->type->showAccountCredit();
}

新的类，UserType代表特殊的行为，然后用户将包含其余的泛型内容，减少您描述的重复(或至少大部分)

另一方面，工厂可以用于从db加载对象：

class Loader{
  private $userTypeFactory;

  public function loadUser($id){
    $userRow = $db->loadRow();
    ...

    $userType = $userTypeFactory->$userRow["type"]();
    return new User($userType);
  }
}

class UserTypeFactory{
  public function vip(){
    return new VipUserType();
  }

  public function premium(){
    return new PremiumUser();
  }
}

您可以更进一步，引入IoC框架。在symfony2上看看吧。哦，请不要使用switch，而是像我一样做，多态，动态调用。

编辑：

策略==包装行为。例如，如果您正在检查查看付费内容的用户权限，则通常如下所示：

class PagesController{
  ...

  public function showPage($id){
    ...
    if ($user->type == "premium" || $user->type == "vip"){
      ...
    }
    else if ($user->type == "credit"){
      $user->credits--;
      updateUser();
    }
    else{
      die("You do not have permissions to see this content...");
    }

    ... //render page
  }
}

下面是使用“策略”时的样子：

class PagesController{
  ...
  public function showPage($id){
    $page = ...;

    $user->pageRequested($page);

    //render page
  }
}

class User{
  private $userType;

  public function pageRequested($page){
    $this->userType->userRequestedPage($user, $page);
  }
}

class VipUserType{
  public function userRequestedPage($user, $page){
    //do nothing
  }
}

class PremiumUserType{
  public function userRequestedPage($user, $page){
    //do nothing
  }
}

class BasicUserType{
  public function userRequestedPage($user, $page){
    throw new Exception("You cant access this page");
  }
}

class CreditUserType{
  public function userRequestedPage($user, $page){
    $user->credit--;
    $user->save();
  }
}

这样，所有与userType相关的东西都被分离了，很容易添加新的类型，而不会有破坏现有类型的风险。

顺便说一句：这只不过是简单的多态。策略只是OOP本质的另一个闪亮的词，就像大多数模式一样。不要浪费时间去思考模式，它们对灵感很有帮助，但是你会从真正的OOP中获得更多的经验，看看smalltalk - http://www.pharo-project.org/home