PHP implementation of simple factory pattern c# simple factory pattern factory pattern java java simple factory pattern example

简单工厂模式又叫静态工厂方法模式，主要作用是通过一个简单工厂类来实例化（创建）各个类的对象，而不需要通过new来实例化对象。优点在于，工厂类中包含了一定的逻辑判断，会根据客户端的选择条件动态实例化相关的类。缺点在于，当需要增加新的功能类时，需要去修改工厂类。

以下内容以一个简单的计算器程序作为案例分析。第一步，定义Operation，是一个父类，有两个属性，表示用于计算的两个参数。

<?php
/*
* 计算类
*/
class Operation{
	private $numA=0;
	private $numB=0;
	public function setNumA($numA)
	{
		$this->numA=$numA;
	}

	public function getNumA()
	{
		return $this->numA;
	}

	public function setNumB($numB)
	{
		$this->numB=$numB;
	}

	public function getNumB()
	{
		return $this->numB;
	}
}
?>

The second step is to define an interface, which declares the method to implement the operation

<?php
/*
*工厂接口
*/
interface InterOperate{
	function getResult();
}
?>

The third step is an addition operation class (omitting the subtraction class, multiplication class, trigger class, etc.)

<?php

/**
* 加法运算类
*/
include_once "IOperate.php";
include_once &#39;Operation.php&#39;;
class OperationAdd extends Operation implements InterOperate
{
	function getResult()
	{
		$result=$this->getNumA()+$this->getNumB();
		return $result;
	}
}

?>

Finally, define a simple factory class for creating object instances of various classes. Usually the objects returned by simple factory classes have a common parent class. In this example, the common parent class is the Operation class, and the addition class and the subtraction class are both subclasses of Operation.

<?php
include_once "OperationAdd.php";
include_once "OperationMinus.php";
class SimpleFactory {
	static function createAdd()
	{
		return new OperationAdd;
	}

	static function createMinus()
	{
		return new OperationMinus;
	}
}

?>

The client code is as follows:

<?php
/*
*	客户端代码
*/
include_once "OperationAdd.php";
include_once &#39;Operation.php&#39;;
include_once &#39;SimpleFactory.php&#39;;

$op=SimpleFactory::createAdd();
$op->setNumA(2);
$op->setNumB(4);
echo $op->getResult();

$om=SimpleFactory::createMinus();
$om->setNumA(45);
$om->setNumB(34);
echo "<br>";
echo $om->getResult();
?>

The above introduces the PHP implementation of the simple factory pattern, including the content of the simple factory pattern. I hope it will be helpful to friends who are interested in PHP tutorials.