oop编程的三大特征

封装 继承 多态

一,抽象的概念

把一类事物的共有的属性(成员属性)和行为(成员方法)提取出来,形成一个模型,这种研究问题的方法就是抽象

二.封装

将抽象出的数据和对数据的操作封装在一起,数据被保护在内部,程序的其他部分只有通过被授权的操作(成员方法),才能对数据进行操作

封装的具体实现--访问修饰符:public protected private

1.如何访问protected和private属性的三种方式

①魔术方法__get和__set

缺点:不能单独控制某一个属性

<?php
class Person{
    public $name;
    protected $nickname;
    private $address;
　　//初始化数据
    public function __construct($name,$nickname,$address){
        $this->name = $name;
        $this->nickname = $nickname;
        $this->address = $address;
    }
    //魔术方法
　　//参数:$pro_name 属性名  $pro_val 属性值
    public function __set($pro_name,$pro_val){
        if(property_exists($this,$pro_name)){
            $this->$pro_name = $pro_val;
        }else{
            echo '属性不存在';
        }
    }
    public function __get($pro_name){
        if(property_exists($this,$pro_name)){
            return $this->$pro_name;
        }
    }
}
$p1 = new Person('小明','明明','花果山');
$p1->nickname = '红红';
$p1->address = '泰山';
echo $p1->nickname;
echo $p1->address;

 ②对每一个protected和private属性提供一堆get/set方法,这样就可以分别控制各个属性

优点:可以对每个属性进行单独操作

缺点:每个属性会有一对get和set方法,所以属性越多 get和set方法越多

<?php
class Person{
    public $name;
    protected $nickname;
    private $address;

    public function __construct($name,$nickname,$address){
        $this->name = $name;
        $this->nickname = $nickname;
        $this->address = $address;
    }
    //单独定义方法去设置相应的属性
    public function setNickname($pro_name){
            $this->nickname = $pro_name;
    }
    public function getNickname(){
            return $this->nickname;
    }
}
$p1 = new Person('小明','明明','花果山');
$p1->setNickname('红红');
$p1->getNickname();
var_dump($p1);
var_dump($p1->getNickname());

③写一个成员方法,可以根据业务逻辑,一次性对多个属性进行批量操作

class Movie{
    //Movie(名称,导演,成本,票房)
    public $name;
    public $director;
    protected $cost;
    private $tickeoffice;

    public function __construct($name,$director,$cost){
        $this->name = $name;
        $this->director = $director;
        $this->cost = $cost;
    }
    //显示一下电影信息
    public function showAllInfo(){
        echo '<br> 电影信息如下:';
        echo '<br> name = '.$this->name;
        echo '<br> director = '.$this->director;
        echo '<br> cost = '.$this->cost;
        echo '<br> tickeoffice = '.$this->tickeoffice;
    }
    public function updateInfo($director,$cost,$tickeoffice){
        //简单方式
        $this->director = $director;
//      $this->cost = $cost;
//      $this->tickeoffice = $tickeoffice;
        //另外一种方法
        $this->setCost($cost);
        $this->setickeoffice($tickeoffice);
    }
    //修改成本
    public function setCost($cost){
        //加入数据的验证和判断 is_numeric()用来判断是不是数字格式
        if(is_numeric($cost)&&$cost>0.0){
            $this->cost = $cost;
        }else{
            echo '输入成本格式有问题';
        }
    }
    //修改票房
    public function setickeoffice($tickeoffice){
        //加入数据的验证和判断 is_numeric()用来判断是不是数字格式
        if(is_numeric($tickeoffice)&&$tickeoffice>0.0){
            $this->tickeoffice = $tickeoffice;
        }else{
            echo '输入票房格式有问题';
        }
    }
}
$movie = new Movie('葫芦娃','老爷子',60000);
$movie->updateInfo('小明','80000','620000');
$movie->showAllInfo();

 2,封装的细节

普通属性定义时必须写访问修饰符,public protected 或private,如果用var定义默认为公有

静态属性定义时,可以写访问修饰符,public protected 或private,如果是公有时可以不写public

类的方法可以定义为public protected 或private,如果是公有时可以不写public

3.对象运算符的连用

//学生类
class student{
    public $name;
    private $school;
    //构造函数
    public function __construct($name,$school){
        $this->name = $name;
        $this->school = $school;
    }
    //给$school 提供setX学习和setXxx方法
    public function getSchool(){
        return $this->school;
    }
    public function setSchool(){
        $this->school = $school;
    }
}


//学校类
class School{
    public $name;
    public $address;
    private $my_class;
    //构造函数
    public function __construct($name,$address,$my_class){
        $this->name = $name;
        $this->address = $address;
        $this->my_class = $my_class;
    }
    //给$my_class 提供setX学习和setXxx方法
    public function getMyclass(){
        return $this->my_class;
    }
    public function setMyclass(){
        $this->my_class = $my_class;
    }
}

//班级类
class Myclass{
    protected $name;
    protected $stu_num;
    private $introduce;
    //构造函数
    public function __construct($name,$stu_num,$introduce){
        $this->name = $name;
        $this->stu_num = $stu_num;
        $this->introduce = $introduce;
    }
    //$introduce 提供setX学习和setXxx方法
    public function getintroduce(){
        return $this->introduce;
    }
    public function setMyclass(){
        $this->introduce = $introduce;
    }
}
//创建班级对象
$myClass = new Myclass('2005级应化一班',32,'2005级化学院');
//var_dump($myClass);
//创建学校对象
$school = new School('山东农业大学','山东泰安',$myClass);
//var_dump($school);
//创建学生对象
$student = new student('小明',$school);
//var_dump($student);
//通过$student对象,找到对应的班级信息
var_dump($student->getSchool()->getMyclass()->getintroduce());