Factory pattern:
The factory class determines which instance of the product class to create based on the parameters;
The factory class refers to a class that contains a method specifically used to create other objects. The so-called on-demand allocation is to pass in parameters for selection and return a specific class. The main function of the factory pattern is to encapsulate object creation and simplify object creation operations.
Simply put, it is to call a method of the factory class (pass in parameters) to get the required class;
Code implementation:
Example 1 (the most basic factory class):
<?php class MyObject { public function __construct(){} public function test(){ return '测试'; } } class MyFactory { public static function factory(){ //返回对象的实例 return new MyObject(); } } //调用工厂类MyFactory中的静态方法,获取类MyObject的实例 $myobject=MyFactory::factory(); echo $myobject->test();
Example 2:
<?php //简单工厂模式 /1* * 定义运算类 */ abstract class Operation { protected $_NumberA = 0; protected $_NumberB = 0; protected $_Result = 0; public function __construct($A,$B){ $this->_NumberA = $A; $this->_NumberB = $B; } public function setNumber($A,$B){ $this->_NumberA = $A; $this->_NumberB = $B; } /1* protected function clearResult(){ $this->_Result = 0; } */ public function clearResult(){ $this->_Result = 0; } //抽象方法无方法体 abstract protected function getResult(); } //继承一个抽象类的时候,子类必须实现抽象类中的所有抽象方法; //另外,这些方法的可见性 必须和抽象类中一样(或者更为宽松) class OperationAdd extends Operation { public function getResult(){ $this->_Result=$this->_NumberA + $this->_NumberB; return $this->_Result; } } class OperationSub extends Operation { public function getResult(){ $this->_Result=$this->_NumberA - $this->_NumberB; return $this->_Result; } } class OperationMul extends Operation { public function getResult(){ $this->_Result=$this->_NumberA * $this->_NumberB; return $this->_Result; } } class OperationDiv extends Operation { public function getResult(){ $this->_Result=$this->_NumberA / $this->_NumberB; return $this->_Result; } } class OperationFactory { //创建保存实例的静态成员变量 private static $obj; //创建访问实例的公共的静态方法 public static function CreateOperation($type,$A,$B){ switch($type){ case '+': self::$obj = new OperationAdd($A,$B); break; case '-': self::$obj = new OperationSub($A,$B); break; case '*': self::$obj = new OperationMul($A,$B); break; case '/': self::$obj = new OperationDiv($A,$B); break; } return self::$obj; } } //$obj = OperationFactory::CreateOperation('+'); //$obj->setNumber(4,4); $obj = OperationFactory::CreateOperation('*',5,6); echo $obj->getResult(); /1* echo '<br>'; $obj->clearResult(); echo '<br>'; echo $obj->_Result; */
Example 3:
<?php //抽象工厂 //青铜会员的打折商品 class BronzeRebateCommodity { //描述 public $desc = '青铜会员的打折商品'; } //白银会员的打折商品 class SilverRebateCommodity { public $desc = '白银会员的打折商品'; } //青铜会员的推荐商品 class BronzeCommendatoryCommodity { public $desc = '青铜会员的推荐商品'; } //白银会员的推荐商品 class SilverCommendatoryCommodity { public $desc = '白银会员的推荐商品'; } //各个工厂的接口 interface ConcreteFactory { //生产对象的方法 public function create($what); } //青铜工厂 class BronzeFactory implements ConcreteFactory { //生产对象的方法 public function create($what){ $productName = 'Bronze'.$what.'Commodity'; return new $productName; } } //白银工厂 class SilverFactory implements ConcreteFactory { //生产对象的方法 public function create($what){ $productName = 'Silver'.$what.'Commodity'; return new $productName; } } //调度中心 class CenterFactory { //获取工厂的方法 public function getFactory($what){ $factoryName = $what.'Factory'; return new $factoryName; } //获取工厂的静态方法 public static function getFactory2($what){ $factoryName = $what.'Factory'; return new $factoryName; } } //实例化调度中心 $center = new CenterFactory(); //获得一个白银工厂 $factory = $center->getFactory('Silver'); //让白银工厂制造一个推荐商品 $product = $factory->create('Commendatory'); //得到白银会员的推荐商品 echo $product->desc.'<br>'; //获得一个青铜工厂 $factory2 = CenterFactory::getFactory2('Bronze'); //让青铜工厂制造一个打折商品 $product2 = $factory2->create('Rebate'); //得到青铜会员的推荐商品 echo $product2->desc;
Example 4:
<?php //使用工厂类解析图像文件 interface IImage { function getWidth(); function getHeight(); function getData(); } class Image_PNG implements IImage { protected $_width,$_height,$_data; public function __construct($file){ $this->_file = $file; $this->_parse(); } private function _parse(){ //完成PNG格式的解析工作 //并填充$_width,$_height和$_data $this->_data = getimagesize($this->_file); list($this->_width,$this->_height)=$this->_data; } public function getWidth(){ return $this->_width; } public function getHeight(){ return $this->_height; } public function getData(){ return $this->_data; } } class Image_JPEG implements IImage { protected $_width,$_height,$_data; public function __construct($file){ $this->_file = $file; $this->_parse(); } private function _parse(){ //完成JPEG格式的解析工作 //并填充$_width,$_height和$_data //$this->_width = imagesx($this->_file); //$this->_height = imagesy($this->_file); $this->_data = getimagesize($this->_file); list($this->_width,$this->_height)=$this->_data; } public function getWidth(){ return $this->_width; } public function getHeight(){ return $this->_height; } public function getData(){ return $this->_data; } } //工厂类 class ImageFactory { public static function factory($file){ $filename = pathinfo($file); switch(strtolower($filename['extension'])){ case 'jpg': $return = new Image_JPEG($file); break; case 'png': $return = new Image_PNG($file); break; default: echo '图片类型不正确'; break; } if($return instanceof IImage){ return $return; }else{ echo '出错了'; exit(); } } } $image = ImageFactory::factory('images/11.jpg'); var_dump($image->getWidth()); echo '<br>'; print_r($image->getheight()); echo '<br>'; print_r($image->getData());
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