simple--factory--abstract

<?php
/* 示例2： */
//简单工厂模式
/*
 * 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;
    }

    /* protected function clearResult(){
        $this->_Result  = 0;
    } */

    public function clearResult(){
        return $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();        //
echo "<br/>";
echo $obj->clearResult();    //
echo '<br>';
/* echo $obj->_Result; */