php 给对象私有及受保护的成员变量赋值的几种方法

1.构造方法赋值

<?php
class City{
	private $_cityName;
	private $_population;
	
	//function city($_cityName,$_population){}  php5.3.3起在有命名空间的类中，类同名方法不再视为构造方法而是常规方法，无命名空间类中不影响
	public function __construct($_cityName,$_population){
		$this->_cityName = $_cityName;
		$this->_population = $_population;
	}
	
	public function getCityName(){
		return $this->_cityName;
	}
	
	public function getPopulation(){
		return $this->_population;
	}
}

$nanjing = new City("南京",10000000);
echo "城市：".$nanjing->getCityName(),"<br/>";		//城市：南京
echo "人口：".$nanjing->getPopulation(),"<br/>";	//人口：10000000

2.魔术方式赋值和调用：__set()、__get()

<?php
class City{
	private $_cityName;
	private $_population;
	
	//magic method: __set()  
	/**
	当给一个无访问权限或不存在的属性赋值时，__set()魔术方法会自动调用，并传入两个参数：属性和属性值
	$suzhou->_cityName="苏州" ---无权访问权限--> __set("_cityName","苏州");
	**/
	public function __set($property_name,$property_value){
		$this->$property_name = $property_value;
	}
	
	//magic method: __get()
	/**
	当我们调用一个权限上不允许访问的属性或者是不存在的属性时，__get()魔术方法会自动调用，并且自动传参，参数名是属性名
	$suzhou->_cityName ---无访问权限--> __get(_cityName);
	**/
	public function __get($property_name){
		if(isset($this->$property_name)){
			return $this->$property_name;	
		}else{
			return null;
		}
		
	}
}


//设置__set()和__get()方法，可以在类外部像给public修饰的成员变量一样赋值和调用
$suzhou = new City();
$suzhou->_cityName = "苏州";  
$suzhou->_population = 7000000;
echo "城市：".$suzhou->_cityName,"<br/>";	//城市：苏州
echo "人口：".$suzhou->_population,"<br/>";	//人口：7000000

3.调用类常规方法传参赋值

<?php
class City{
	private $_cityName;
	private $_population;

	private $_factory;
	
	function setCityName($_cityName){
		$this->_cityName = $_cityName; 
	}
	
	function setPopulation($_population){
		$this->_population = $_population;
	}
	
	function getCityName(){
		return $this->_cityName;
	}
	
	function getPopulation(){
		return $this->_population;
	}

	
	//
	function set($name,$value){
		$this->_factory[$name] = $value;//以数组的形式存储变量赋值
	}
	
	function get($name){
		return $this->_factory[$name];
	}
}


$shanghai = new City();
//通过函数传参的形式给对象指定私有变量赋值，通过指定函数获取指定私有变量值
$shanghai->setCityName("上海"); 
$shanghai->setPopulation(30000000);
echo "城市：".$shanghai->getCityName(),"<br/>";  	//城市：上海
echo "人口：".$shanghai->getPopulation(),"<br/>";	//人口：30000000

$shanghai->set("totalArea","6340平方公里");
$shanghai->set("areaCode","017");
$shanghai->set("zipCode",200000);
echo "面积：".$shanghai->get("totalArea"),"<br/>";	//面积：6340平方公里
echo "区号：".$shanghai->get("areaCode"),"<br/>";	//区号：017
echo "邮编：".$shanghai->get("zipCode"),"<br/>";	//邮编：200000