其它常用魔術(shù)方法與實(shí)戰(zhàn)

一、sleep()與weakup()

• __sleep()用serialize關(guān)鍵字序列化時(shí)被自動(dòng)調(diào)用的魔術(shù)方法

• __wakeup()用unserialize關(guān)鍵字反序列化時(shí)被自動(dòng)調(diào)用的魔術(shù)方法

案例1：

<?php
//序列化
//echo serialize('孫悟空');
//echo serialize([1,2,3,true,null]);
class User
{
    public $name = '遙控飛機(jī)';
    public $price = 4000;
    public $num = 3;
    //序列化時(shí)自動(dòng)調(diào)用__sleep()魔術(shù)方法
    public function __sleep():array
    {
        return ['name','price','num'];
    }
    //反序列化時(shí)自動(dòng)調(diào)用
    public function __wakeup()
    {
        $this->price = 1000;
    }
}
$user = new User();
echo serialize($user),'<br>';
//序列化數(shù)據(jù)的目的是將數(shù)據(jù)進(jìn)行傳輸保存
file_put_contents('obj.txt',serialize($user));
$str = file_get_contents('obj.txt');
echo gettype($str).'<br>';
//反序列化
$obj = unserialize($str);
echo gettype($obj).'<br>';
echo $obj->name . ':價(jià)格：' . $obj->price . ',數(shù)量：' , $obj->num;

案例2：

<?php
//__sleep()和__wakeup()實(shí)戰(zhàn)
//自定義數(shù)據(jù)庫(kù)連接類
//功能
//1.類實(shí)例化，自動(dòng)連接數(shù)據(jù)庫(kù)，一定會(huì)生成一個(gè)：連接對(duì)象
//2.將這個(gè)連接對(duì)象序列化，獲取到連接參數(shù)
//3.反序列化，自動(dòng)重新連接數(shù)據(jù)庫(kù)
//連接類
class Connection
{
    //數(shù)據(jù)庫(kù)連接參數(shù)
    private $params = [];
    //連接對(duì)象
    private $link;
    //構(gòu)造方法
    public function __construct($dsn,$username,$password)
    {
        //1.連接參數(shù)的初始化
        $this->params['dsn'] = $dsn;
        $this->params['username'] = $username;
        $this->params['password'] = $password;
        $this->connect();
        //2.連接數(shù)據(jù)庫(kù)
        //$this->link = new PDO(...$this->params);
    }
    //連接數(shù)據(jù)庫(kù)
    public function connect()
    {
        //array_values()把關(guān)聯(lián)數(shù)組轉(zhuǎn)換為索引數(shù)組
        $this->link = new PDO(...array_values($this->params));
    }
    //將這個(gè)連接對(duì)象序列化，獲取到連接參數(shù)
    public function __sleep():array
    {
        return ['params'];
    }
    //反序列化，自動(dòng)重新連接數(shù)據(jù)庫(kù)
    public function __wakeup()
    {
        $this->connect();
    }
    public function select($sql)
    {
        return $this->link->query($sql)->fetchAll(PDO::FETCH_ASSOC);
    }
}
$dsn = 'mysql:host=localhost;dbname=tp5';
$username = 'root';
$password = 'wang1111';
$db = new Connection($dsn,$username,$password);
//var_dump($db);
$str = serialize($db);
echo $str.'<hr>';
//print_r(unserialize($str));
print_r($db->select('SELECT * FROM user LIMIT 3'));
echo '<hr>';
//3.反序列化，自動(dòng)重新連接數(shù)據(jù)庫(kù)
$link = unserialize($str);
print_r($link);

二、__toString()

• __toString() 方法用于一個(gè)類被當(dāng)成字符串輸出時(shí)自動(dòng)調(diào)用該魔術(shù)方法

<?php
//tostring()
class User
{
    public function __toString()
    {
        return 'Hello';
    }
}
//將這個(gè)類的實(shí)例，當(dāng)成字符串打印
$user = new User();
echo $user;
class DbException extends PDOException
{
    public function __toString()
    {
        return <<< DBE
        <table border="1px">
            <tr>
                <td>編號(hào)</td>
                <td>信息</td>
                <td>文件</td>
                <td>行號(hào)</td>
            </tr>
            <tr>
                <td>$this->code</td>
                <td>$this->message</td>
                <td>$this->file</td>
                <td>$this->line</td>
            </tr>
        </table>
DBE;
    }
}
try{
    $db = new PDO('mysql:host=localhost;dbname=tp5','root','wang11112');
}catch(PDOException $e){
    $error = new DbException('連接錯(cuò)誤',1001);
    echo $error;
}

三、匿名類

• 匿名類可以創(chuàng)建一次性的簡(jiǎn)單對(duì)象

• 可以傳遞參數(shù)到匿名類的構(gòu)造器，也可以擴(kuò)展（extend）其他類、實(shí)現(xiàn)接口（implement interface），以及像其他普通的類一樣使用

<?php
//匿名類的應(yīng)用場(chǎng)景
//1.實(shí)現(xiàn)接口的部分功能
interface iDb 
{
    public function __construct(...$params);
}
//當(dāng)前這個(gè)接口中的數(shù)據(jù)連接操作應(yīng)該支持PDO,mysqli
//mysqlu實(shí)現(xiàn)
class My_mysqli implements iDb
{
    private $db = null;
    public function __construct(...$params)
    {
        $this->db = new mysqli($params[0],$params[1],$params[2],$params[3]);
        echo '數(shù)據(jù)庫(kù)連接成功';
    }
    public function select()
    {
       return $this->db->query('SELECT * FROM user LIMIT 2')->fetch_all(MYSQLI_ASSOC);
    }
}
$mysqli = new My_mysqli('localhost','root','wang1111','tp5');
print_r($mysqli->select());
echo '<hr>';
//匿名類實(shí)現(xiàn)
$users = ( new class ('localhost','root','wang1111','tp5') implements iDb{
    private $db = null;
    public function __construct(...$params)
    {
        $this->db = new mysqli($params[0],$params[1],$params[2],$params[3]);
        echo '數(shù)據(jù)庫(kù)連接成功';
    }
    public function select()
    {
       return $this->db->query('SELECT * FROM user LIMIT 2')->fetch_all(MYSQLI_ASSOC);
    }
})->select();
print_r($users);
echo '<hr>';
//用pdo來實(shí)現(xiàn)
class My_pdo implements iDb
{
    private $db = null;
    public function __construct(...$params)
    {
        $this->db = new PDO($params[0],$params[1],$params[2]);
        echo '數(shù)據(jù)庫(kù)連接成功';
    }
    public function select()
    {
       return $this->db->query('SELECT * FROM user LIMIT 1')->fetchAll(PDO::FETCH_ASSOC);
    }
}
$mypdo = new My_pdo('mysql:host=localhost;dbname=tp5','root','wang1111');
print_r($mypdo->select());
echo '<hr>';
//用匿名類來實(shí)現(xiàn)
$users2 = ( new class ('mysql:host=localhost;dbname=tp5','root','wang1111') implements iDb{
    private $db = null;
    public function __construct(...$params)
    {
        $this->db = new PDO($params[0],$params[1],$params[2]);
        echo '數(shù)據(jù)庫(kù)連接成功';
    }
    public function select()
    {
       return $this->db->query('SELECT * FROM user LIMIT 2')->fetchAll(PDO::FETCH_ASSOC);
    }
})->select();
print_r($users2);
echo '<hr>';

四、學(xué)習(xí)總結(jié)

• 序列化時(shí)自動(dòng)調(diào)用__sleep()魔術(shù)方法

• 反序列化時(shí)自動(dòng)調(diào)用__wakeup()魔術(shù)方法

• 當(dāng)echo一個(gè)實(shí)例化的類時(shí)，自動(dòng)調(diào)用__toString()魔術(shù)方法

• 匿名類，沒有名稱的類，通常賦值給一個(gè)變量

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