<?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->b = $b;		$this->oper = $oper;	}		public function getresult(){		switch ($this->oper){			case 1: $model = new add($this->a,$this->b);break;			case 2: $model = new jian($this->a,$this->b);break;			case 3: $model = new cheng($this->a,$this->b);break;			case 4: $model = new chu($this->a,$this->b);break;		}		return $model->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){		$this->a =$a;		$this->b = $b;	}	abstract function result();}//子类，负责具体业务实现class add extends poper{	public function result(){		return $this->a+$this->b;	}}class jian extends poper{	public function result(){		return $this->a-$this->b;	}}class cheng extends poper{	public function result(){		return $this->a*$this->b;	}}class chu extends poper{	public function result(){		if($this->b ==0){			return ‘除数不能为0‘;		}		return $this->a/$this->b;	}}?>