Detailed explanation of commonly used keywords and magic methods in PHP object-oriented-PHP Tutorial-php.cn

1.construct()

The instantiated object is automatically called. Construct is called when construct and the function with the class name and function name exist at the same time, and the other one is not called.

The function with the class name and function name is the old version of the constructor.

2.destruct()

is called when deleting an object or when an object operation ends.

3.call()

The object calls a method. If the method does not exist, call this method

4.get()

Read an object property. If the object property is private, it will be called

5. set()

When assigning a value to an object property, it will be called if the property is private

6.toString()

It will be called when printing an object.

7.clone()

Called when cloning an object, such as: $a=new test(); $a1=clone $a;

8.sleep( )

Serialize was called before. If the object is larger than and you want to delete something during serialization, you can use it.

9.wakeup()

is called when Unserialize is used to do some object initialization work.

10.isset()

Detects whether an object's attributes exist. If the detected attribute is private, it will be called.

11.unset()

When deleting an object attribute, if the deleted object attribute is private, it will be called

12.set_state()

Called when var_export is called. Use the return value of set_state as the return value of var_export.

13.autoload()

When instantiating an object, if the corresponding class does not exist, this method will be used.

The following editor will bring you a detailed discussion of PHP object-orientedcommonly used keywords and magic methods. The editor thinks it’s pretty good, so I’ll share it with you now and give it as a reference. Let’s follow the editor and take a look.

Commonly used keywords in PHP object-oriented

final

1.Final cannot modify member attributes (this keyword is not used for constants in classes)

2.Final can only modify classes and methods

Function:

Classes modified with final cannot be inherited by subclasses

Methods modified with final cannot be overridden by subclasses

Used to restrict classes from being inherited, methods If not overridden, use final

<?php
//final修饰的类不能被继承
final class Person{
  var $name;
  var $age;
  var $sex;

  function construct($name,$age,$sex){
    $this->name=$name;
    $this->age=$age;
    $this->sex=$sex;
  }

  function fun1(){
    echo $this->name;
  }
}

//Student类继承类用final修饰的Person类，所以会报错
class Student extends Person{
}

$stu=new Student("zs",20,"nan");

$stu->fun1();
?>

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static (static keyword)

1. Use static to modify member properties and member methods, but not Modified class

2. Member attributes modified with static can be shared by all objects of the same class

3. Static data is stored in the data segment in memory (initializing the static segment)

4. Static data is allocated to memory when the class is loaded for the first time. When the class is used in the future, it is obtained directly from the data segment

5. What is a class being loaded? As long as this class is used in the program (this class name appears)

6. Static methods (static modified methods) cannot access non-static members (static members can be accessed in non-static methods)

Because non-static members must be accessed using objects, $this is used to access internal members. Static methods do not need to be called using objects, so there is no object. $this cannot represent objects. Non-static Members must also use objects

If you are sure that non-static members are not used in a method, you can declare this method as a static method

Note: Static members must use class names To access, don’tCreate an object, don’t use an object to access

Class name::static member

If you use static members in a class, you can use self to represent this class

const

1. It can only modify member attributes

2. Use const

# to declare constant attributes in a class ##3. The access method is the same as static member properties (use class name::constant outside the class and self::constant inside the class)

4. Constants must be given initial values when they are declared.

<?php
//定义一个类“人们”
class Person{
  protected $name;
  protected $age;
  protected $sex;
  static $country="中国";
  //声明一个常量
  const RUN="走";

  //构造方法
  function construct($name,$age,$sex){
    $this->name=$name;
    $this->age=$age;
    $this->sex=$sex;
  }

  function getCountry(){
    //如果在类中使用静态成员，可以使用self代表本类
    return self::$country;
  }

  function say(){
    echo "我的名字：{$this->name}，我的年龄：{$this->age}，我的性别：{$this->sex}。<br>";
  }

  protected function eat(){
    echo "吃饭！<br>";
  }

  function run(){
    //在类的内部使用常量 self::常量
    echo self::RUN."<br>";
  }

  //声明静态的方法
  static function hello(){
    echo "你好<br>";
  }
}

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Magic methods commonly used in PHP object-oriented

call()

Function: When calling a method that does not exist in the object, a system error will appear, and then the program will exit.

When to call automatically: It will be called automatically when calling a method that does not exist in an object

Handle some non-existent error calls

This method requires two Parameters

<?php
//定义一个类“人们”
class Person{
  protected $name;
  protected $age;
  protected $sex;
  static $country="中国";
  //声明一个常量
  const RUN="走";

  //构造方法
  function construct($name,$age,$sex){
    $this->name=$name;
    $this->age=$age;
    $this->sex=$sex;
  }

  function getCountry(){
    //如果在类中使用静态成员，可以使用self代表本类
    return self::$country;
  }

  function say(){
    echo "我的名字：{$this->name}，我的年龄：{$this->age}，我的性别：{$this->sex}。<br>";
  }

  protected function eat(){
    echo "吃饭！<br>";
  }

  function run(){
    //在类的内部使用常量 self::常量
    echo self::RUN."<br>";
  }

  //处理一些不存在的错误调用
  //就会在调用一个对象中不存在的方法时就会自动调用
  function call($methodName,$args){
    //$methodName调用不存在方法的方法名 $args里面的参数
    echo "你调用的方法{$methodName}（参数：";
    print_r($args);
    echo "）不存在<br>";
  }

  //声明静态的方法
  static function hello(){
    echo "你好<br>";
  }
}

$p=new Person("张三",20,"女");

$p->test(10,20,30);
$p->demo("aa","bb");
$p->say();
?>

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toString()

is automatically called when directly outputting an object reference. It is the fastest way to quickly obtain a string representation. Method

<?php
//定义一个类“人们”
class Person{
  protected $name;
  protected $age;
  protected $sex;
  static $country="中国";
  //声明一个常量
  const RUN="走";

  //构造方法
  function construct($name,$age,$sex){
    $this->name=$name;
    $this->age=$age;
    $this->sex=$sex;
  }

  function say(){
    echo "我的名字：{$this->name}，我的年龄：{$this->age}，我的性别：{$this->sex}。<br>";
  }

  function toString(){
    return self::$country."<br>{$this->name}<br>{$this->age}<br>{$this->sex}<br>".self::RUN;
  }
}

$p=new Person("张三",21,"女");
echo $p;
?>

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clone()

Clone object is processed using clone()

Original (original object)

Copy (copied object)

clone() is a method automatically called when cloning an object

As soon as an object is created, there must be an initialization action, and The constructor method constuct has similar functions

在clone()方法中的$this关键字代表的是复本的对象,$that代表原本对象

<?php
//定义一个类“人们”
class Person{
  var $name;
  protected $age;
  protected $sex;
  static $country="中国";
  //声明一个常量
  const RUN="走";

  //构造方法
  function construct($name,$age,$sex){
    $this->name=$name;
    $this->age=$age;
    $this->sex=$sex;
  }

  function say(){
    echo "我的名字：{$this->name}，我的年龄：{$this->age}，我的性别：{$this->sex}。<br>";
  }

  function clone(){
    $this->name="王五";
    $this->age=18;
    $this->sex="男";
  }

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

$p=new Person("张三",21,"女");
$p->say();
//这并不能叫做克隆对象，因为在析构时只析构一次
/*$p1=$p;
$p1->name="李四";
$p1->say();*/

$p1= clone $p;
$p1->say();
?>

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autoload()

注意：其它的魔术方法都是在类中添加起作用，这是唯一一个不在类中添加的方法

只要在页面中使用到一个类，只要用到类名，就会自动将这个类名传给这个参数

<?php
function autoload($className){
  include "./test/".$className.".class.php";
}

  $o=new One;
  $o->fun1();  

  $t=new Two;
  $t->fun2();

  $h=new Three;
  $h->fun3();

?>

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test里的文件

one.class.php

<?php
class One{
  function fun1(){
    echo "The Class One<br>";
  }
}
?>

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two.class.php

<?php
class Two{
  function fun2(){
    echo "The Class Two<br>";
  }
}
?>

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three.class.php

<?php
class Three{
  function fun3(){
    echo "The Class Three<br>";
  }
}
?>

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对象串行化（序列化）：将一个对象转为二进制串（对象是存储在内存中的，容易释放）

使用时间：

1.将对象长时间存储在数据库或文件中时

2.将对象在多个PHP文件中传输时

serialize(); 参数是一个对象，返回来的就是串行化后的二进制串

unserialize(); 参数就是对象的二进制串，返回来的就是新生成的对象

sleep()

是在序列化时调用的方法

作用：就是可以将一个对象部分串行化

只要这个方法中返回一个数组，数组中有几个成员属性就序列化几个成员属性，如果不加这个方法，则所有成员都被序列化

wakeup()

是在反序列化时调用的方法

也是对象重新诞生的过程

<?php
//定义一个类“人们”
class Person{
  var $name;
  protected $age;
  protected $sex;
  static $country="中国";
  //声明一个常量
  const RUN="走";

  //构造方法
  function construct($name,$age,$sex){
    $this->name=$name;
    $this->age=$age;
    $this->sex=$sex;
  }

  function say(){
    echo "我的名字：{$this->name}，我的年龄：{$this->age}，我的性别：{$this->sex}。<br>";
  }

  function clone(){
    $this->name="王五";
    $this->age=18;
    $this->sex="男";
  }

  //是在序列化时调用的方法，可以部分串行化对象
  function sleep(){
    return array("name","age");
  }

  //是在反序列化时调用的方法，也是对象重新诞生的过程。可以改变里面的值
  function wakeup(){
    $this->name="sanzhang";
    $this->age=$this->age+1;
  }

  function destruct(){

  }
}
?>

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read.php

<?php
  require "11.php";
  
  $str=file_get_contents("mess.txt");
  $p=unserialize($str);

  echo $p->say();
?>

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write.php

<?php
  require "11.php";

  $p=new Person("张三",18,"男");

  $str=serialize($p);

  file_put_contents("mess.txt",$str);
?>

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