PHP类(三)-类的封装

设置私有成员

使用private关键字来设置私有成员，完成对成员的封装，封装后的成员在对象的外部不能被访问，如果访问会出现错误，在对象的内部能访问被封装的成员属性和方法。

<?php
	class Person{
		//封装属性
		private $name;
		private $age;
		private $sex;

		function __construct($name="Tom",$age=23,$sex="Male"){
			$this->name = $name;
			$this->age = $age;
			$this->sex = $sex;
		}

		function Say(){
			echo "My name is ".$this->name.",and my age is ".$this->age.",sex is ".$this->sex;
		}

		private function Walk(){
			echo $this->name." is Walk.";
		}
	}

	$p1 = new Person();
	$p1->Say();
	$p1->Walk();
	$p1->age = 25;
?>

执行结果

My name is Tom,and my age is 23,sex is Male
Fatal error: Call to private method Person::Walk() from context '' in C:\phpStudy\WWW\php\lei\FengZhuang.php on line 25
Fatal error: Cannot access private property Person::$age in C:\phpStudy\WWW\php\lei\FengZhuang.php on line 26

私有成员的访问

在对象外如果想获取私有属性的值，或者想给私有属性赋值，可以使用public关键字或者在对象内部声明一些操作私有属性的方法

类中的构造方法默认为公有方法，构造方法不要设置成私有的

<?php
	class Person{
		private $name;
		private $age;
		private $sex;

		function __construct($name="Tom",$age=23,$sex="Male"){
			$this->name = $name;
			$this->age = $age;
			$this->sex = $sex;
		}

		function Say(){
			echo "My name is ".$this->name.",and my age is ".$this->age.",sex is ".$this->sex;
			echo "<br>";
		}

		public function Walk(){
			echo $this->name." is Walk.";
			echo "<br>";
		}

		public function SetAge($age){
			if($age >100 || $age <0)
				return;
			else
				$this->age = $age;
				return $this->age;
		}
	}

	$p1 = new Person();
	$p1->Say();
	$p1->Walk();
	$p1->SetAge(53);
?>

运行结果