php实现设计模式之 简单工厂模式

<?php /*
 * 工厂类，里面包含工厂方法，代替new操作，由参数决定创建哪一种对象
 */
class operator{
	public $a,$b,$oper;
	
	public function __construct($a,$b,$oper){
		$this->a = $a;
		$this-&gt;b = $b;
		$this-&gt;oper = $oper;
	}
	
	public function getresult(){
		switch ($this-&gt;oper){
			case 1: $model = new add($this-&gt;a,$this-&gt;b);break;
			case 2: $model = new jian($this-&gt;a,$this-&gt;b);break;
			case 3: $model = new cheng($this-&gt;a,$this-&gt;b);break;
			case 4: $model = new chu($this-&gt;a,$this-&gt;b);break;
		}
		return $model-&gt;result();
	}
}

/*
 * 抽象类，其子类必须实现运算方法
 */
abstract class poper{
	public $a,$b;
	public function __construct($a,$b){
		$this-&gt;a =$a;
		$this-&gt;b = $b;
	}
	abstract function result();
}

//子类，负责具体业务实现
class add extends poper{
	public function result(){
		return $this-&gt;a+$this-&gt;b;
	}
}

class jian extends poper{
	public function result(){
		return $this-&gt;a-$this-&gt;b;
	}
}

class cheng extends poper{
	public function result(){
		return $this-&gt;a*$this-&gt;b;
	}
}
class chu extends poper{
	public function result(){
		if($this-&gt;b ==0){
			return '除数不能为0';
		}
		return $this-&gt;a/$this-&gt;b;
	}
}
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