php中如何在外部修改类的私有或受保护属性值

在做单元测试框架时，发现了个比较郁闷的问题：测试人员需要在类外修改类的private或protected成员变量的值，而这些变量没有抽象成public的属性，同时为了代码量的问题，也不可能修改要测试的类。怎么在类外修改类的私有变量呢？请看下面的关键代码：

类文件sellAction.php， 内容如下：

<?php
class SellAction{
	protected $cUid;
	private $id;
	public $pId;

	public function output(){
		echo "output protected cUid :".$this->cUid;
		echo "<br/>";
		echo "output private id :".$this->id;
		echo "<br/>";
		echo "output public pId:".$this->pId;
		echo "<br/>";
	}
}

<?php

require "sellAction.php";

function initReferenceAttr(& $reference, $arr)
{
	
        if(!is_object($reference))
        {
            throw new Exception('reference must be object');
        }

        if(!is_array($arr))
        {
            throw new Exception('arr must be array');
        }
	
	$cls = get_class($reference);
	$reflectCls = new ReflectionClass ($cls);

        foreach($arr as $key => $val)
        {
            	$pro = $reflectCls->getProperty($key);
		if($pro && ($pro->isPrivate() || $pro->isProtected())){
			$pro->setAccessible(true);
			$pro->setValue($reference, $val);
		}else{
			$reference->$key = $val;
		}
        }

        return true;
}

$act = new SellAction();

echo "not set private protect public var";
echo "<br/>";
var_dump($act);
$act->output();
$attr = array('cUid'=>'234556', 'pId'=>'987676757', 'id'=> '782100');
initReferenceAttr($act, $attr);
echo "<br/>";
print_r($attr);
echo "<br/>";
echo "<br/>";
echo "set private protect public var ";
echo "<br/>";
var_dump($act);
echo "<br/>";
$act->output();

在浏览器中，直接浏览test.php，内容大致如下：

not set private protect public var
object(SellAction)#1 (3) { ["cUid":protected]=> NULL ["id":"SellAction":private]=> NULL ["pId"]=> NULL } output protected cUid :
output private id :
output public pId:

Array ( [cUid] => 234556 [pId] => 987676757 [id] => 782100 ) 

set private protect public var 
object(SellAction)#1 (3) { ["cUid":protected]=> string(6) "234556" ["id":"SellAction":private]=> string(6) "782100" ["pId"]=> string(9) "987676757" } 
output protected cUid :234556
output private id :782100
output public pId:987676757

上面的demo主要是通过反射实现该功能。反射功能需要php版本>=5.3，反射的相关信息请参阅：http://php.net/manual/en/book.reflection.php