设计模式——工厂模式

工厂模式是指创建一个类似于工厂的类，通过对类中成员方法的调用返回不同类型的对象。
工厂模式通常创建一个基类，根据对象类型的不同创建不同的扩展类，而工厂类就像生产零件一样，生产出类型不同的对象。在程序中，通过对对象的调用实现不同的功能。
一下代码实现了一个管理系统的例子：

<?php    
abstract class User   
{   
	provite $name = NULL;   
	 
	function User($name)   
	{   
	 $this->name = $name;   
	}   
  
	function getName(){return $this->name;}   
	  
	function ViewAccess(){return "No";}   
	  
	function EditAccess(){return "No";}   
	  
	function DeleteAccess(){return "No";}   
	  
	function ManageAccess(){return "No";}  
}

//普通用户   
class Client extends User   
{   
	function ViewAccess()   
	{   
		return "Yes";   
	}   
}   
  
class Administrator extends User   
{   
	function ViewAccess(){return "Yes";}   
	  
	function EditAccess(){return "Yes";}   
	  
	function DeleteAccess(){return "Yes";}   
}  
class Supporter extends User 
{
	function ViewAccess(){return "Yes";}
	
	function EditAccess(){return "Yes";}
	
	function DeleteAccess(){return "Yes";}
	
	function ManageAccess(){return "Yes";}
}

class Factory
{
	private static $users = ("Simon"=>"Client","Elaine"=>"Administrator","Bob"=>"Supporter");  
	static function Create($name)
	{
		switch (self::$users[$name])  
		{
			case "Client": return new Client($name);
			case "Administrator": return Administrator($name);
			case "Supporter": return Supporter($name);
		}
	}
}
$users = array("Elaine","Simon","Bob");
foreach($users as $user)
{
	$obj = Factory::Create($user);
	echo $obj->getName()."的权限：\n";
	echo "浏览:".$obj->ViewAccess()."\n";
	echo "修改:".$obj->EditAccess()."\n";
	echo "删除:".$obj->DeleteAccess()."\n";
	echo "管理:".$obj->ManageAccess()."\n";
}
?>