php类知识---最疯狂的魔术方法serialize，_sleep,__wakeup,unserialize,__autoload，__clone

• serialize-----把实例化的对象写入文件
• __sleep 调用serialize时触发

<?php

class mycoach
{
    public function __construct($name,$age,$expertin=[]){

        $this->name = $name;
        $this->age = $age;
        $this->expertin=[];
        $this->expertin=$expertin;
    }

    public function __sleep()
    {
        return ['name','age','expertin'];
    }
}

$cpc = new mycoach('陈培昌',,['散打','泰拳', '巴西柔术']);
$srobj = serialize($cpc);
file_put_contents('cpcssecret.txt',$srobj);
?>

关键要点：
----类内部实现的 __sleep()要返回数组数据结构，元素都来自类的属性，以此达到控制哪些类可以写入文件
----serialize方法以对象为参数，返回值就是要写入文件的数据。
生成的文件中记录的对象形如：

O:7:"mycoach":3:{s:4:"name";s:9:"陈培昌";s:3:"age";i:22;s:8:"expertin";a:3:{i:0;s:6:"散打";i:1;s:6:"泰拳";i:2;s:12:"巴西柔术";}}

• unserialize-----把文件中的记录还原为类的实例对象
• __wakeup------执行unserialize时调用，用于执行一些初始化操作

<?php

class mycoach
{
    public function __construct($name,$age,$expertin=[]){

        $this->name = $name;
        $this->age = $age;
        $this->expertin=[];
        $this->expertin=$expertin;
    }

    public function __sleep()
    {
        return ['name','age','expertin'];
    }

    public function __wakeup()
    {
        #用途：还原对象（反序列化）的时候，执行一些初始化操作
        echo "还原为对象"."\n";

    }
}

$objdate = file_get_contents('cpcssecret.txt');
var_dump(unserialize($objdate));
?>

输出结果：
还原为对象
object(mycoach)#1 (3) {
  ["name"]=>
  string(9) "陈培昌"
  ["age"]=>
  int(22)
  ["expertin"]=>
  array(3) {
    [0]=>
    string(6) "散打"
    [1]=>
    string(6) "泰拳"
    [2]=>
    string(12) "巴西柔术"
  }
}

• clone复制对象属性
• __clone可以限制哪些属性可以复制，哪些属性采用自定义

<?php

class bt
{
    protected $master = "徐晓冬";
    private $age;
    public function __construct($name,$srcfrom)
    {
        echo "欢迎来到必图拳馆，我是徐晓冬";
        $this->name = $name;
        //$this->age = $age;
        $this->srcfrom = $srcfrom;
    }
    public function __get($master)
    {
        return $this->$master;
    }

    public function __set($key,$value)
    {
        $this->$key = $value;
    }

    public function self_introduce()
    {
        echo "大家好，我是 ".$this->name. " 今年芳龄 ". $this->age." 来自 ". $this->srcfrom." 我师父是 ".$this->master."\n";
    }

    public function __clone()
    {
        $this->name = '丁大锅';
        $this->age = ;
        $this->srcfrom = '维基泄密';
    }

}

/*$zilong = new bt('吴紫龙',21,'公安大学','徐晓冬');*/
$zilong = new bt('紫龙','公安大学');
$zilong->age=;
$zilong->self_introduce();

$dy = clone $zilong;
$dy ->self_introduce();

• __autoload 唯一在类定义体外使用的方法

<?php

function __autoload($name)
{
   echo "this one ".$name;
   include($name.".php");
}

$cpc = new bt('程劲','塔沟武校');
var_dump($cpc);
?>

输出结果：

this one bt欢迎来到必图拳馆，我是徐晓冬object(bt)# () {
  ["master":protected]=>
  string() "徐晓冬"
  ["age":"bt":private]=>
  NULL
  ["name"]=>
  string() "程劲"
  ["srcfrom"]=>
  string() "塔沟武校"
}