![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
天蓬老师Correction status：qualified
Teacher's comments：你能理解并掌握, 我比你还高兴
Collection
Collection
1、案例演示对象序列化
<?php// 对象序列化与__sleep(), __wakeup()// 1. 序列化echo serialize(100). '<br>';echo serialize('php.cn'). '<br>';echo serialize([80, 'hello', true, null, [12,34]]). '<br>';echo '<hr>';// 2. 序列化一个对象呢?abstract class Dad{protected $name = '胡八一';private $salary = 7788;}class Son extends Dad{public $sex = '男';protected $age = 40;private $isMarried = false;protected static $nationality = '中国/CHINA';public function __get($name){return $this->$name;}public function __sleep(): array{return ['name', 'sex', 'isMarried'];}public function __wakeup(){$this->age = 35;$this->sex = '保密';}}$son = new Son();// file_put_contents('obj_seria.txt', serialize($son));// $str = file_get_contents('obj_seria.txt');// echo $str;// $obj = unserialize($str);// echo '<hr>';// var_dump($obj);// echo '<hr>';echo serialize($son);echo '<hr>';$str = serialize($son);var_dump(unserialize($str));
2、案例演示sleep(), wakeup()
<?php// __sleep(), __wakeup()// 创建数据库连接类,// 1. 实例化的时候, 自动连接,并创建连接对象// 2. 外部对连接对象序列化时, 获取到连接参数// 3. 反序列化的时候, 自动重新连接数据库class Connection{protected $link;private $params = [];// 构造方法public function __construct($dsn, $username, $password){$this->params['dsn'] = $dsn;$this->params['username'] = $username;$this->params['password'] = $password;$this->connect();}public function connect(){$this->link = new PDO(...array_values($this->params));}// 序列化的时候返回连接参数public function __sleep(){return ['params'];}// 反序列化时自动重新连接public function __wakeup(){$this->connect();}// 测试public function select($sql){return $this->link->query($sql)->fetchAll(PDO::FETCH_ASSOC);}}// 客户端$db = new Connection('mysql:host=localhost;dbname=phpedu', 'root','root');print_r($db->select('select * from users limit 3'));echo '<hr>';$str = serialize($db);echo $str , '<br>';// 反序列化, 会重新返回一下新对象,所以要重新连接才能查询$obj = unserialize($str);print_r($obj->select('select * from users limit 3'));
3、对象复制与__clone
<?php// 对象复制与__clone// 对象是引用类型,将对象做为值, 赋值给其它变量的时候, 遵循"引用传递"的规则class User{public $name = '朱老师';public $points = 1000;public function __clone(){$this->points = 0;}}$user1 = new User();// 引用$user2 = $user1;// $user2 就是 $user1的别名$user2->name = '王老师';echo $user1->name;echo '<hr>';// clone 克隆出一个全新对象$user3 = clone $user1;echo $user3->name, '----', $user3->points;
4、自定义异常类, 处理用户登录与验证, 模拟就可以不用表单了
<?php// __toString():把对象当成字符串打印的时候调用class User{public function __toString(){return __METHOD__;}}$user = new User();echo $user;echo '<hr>';// 异常类的典型应用try {// 这里的是用户代码,可能会出错throw new Exception('验证失败');} catch (Exception $e) {echo $e->getMessage();}echo '<hr>';try {$db = new PDO('mysql:host=localhost;dbname=phpedu', 'root', 'root');} catch (Exception $e) {echo $e->getMessage();}echo '<hr>';// 自已创建一个针对数据库操作的异常类class DbException extends Exception{public function __toString(){return <<< DBE<style>table {border-collapse: collapse;border:1px solid black;text-align: center;}td {border:1px solid black;padding: 5px;}tr:first-of-type {background-color:#eee;}tr:last-of-type td {color: coral;}</style><table><tr><td>代码</td><td>信息</td><td>文件</td><td>行号</td></tr><tr><td>$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=phpedu', 'root', 'root');throw new DbException('连接成功', 29);} catch (DbException $e) {echo $e;}
5、案例演示匿名类？
<?php// 匿名类class Demo{public function hello($name){return 'Hello ' . $name;}}// 1. 传统$demo = new Demo();echo $demo->hello('小树小站') , '<hr>';// 2. 如果这个对象只用一次, 可以将实例化与成员访问二合一echo (new Demo())->hello('小树小站') , '<hr>';// 3. 如果这个类只用一次, 索性将类, 类的实例化,成员访问三合一echo (new class{public function hello($name){return 'Hello ' . $name;}})->hello('小树小站') , '<hr>';// 用在什么地方?// 经典场景1: 实现接口部分功能, 仅用在当前项目中interface iDb{public function __construct(...$params);}// 你的项目是使用PDO操作数据库, 但是当前测试脚本使用的是mysqli做一些简单查询, 可以使用匿名类实现这个接口// 用mysqli做一次查询$res = (new class ('mysql:host=localhost;dbname=phpedu', 'root', 'root') implements iDb {private $db = null;public function __construct(...$params){$this->db = new PDO($params[0],$params[1],$params[2]);}public function select($where=""){$where = empty($where) ? '' : ' WHERE ' . $where;return $this->db->query('SELECT id,name,email FROM users ' . $where . ' LIMIT 4')->fetchAll(PDO::FETCH_ASSOC);}})->select();printf('<pre>%s</pre>', print_r($res, true));// 经典场景2: 用在函数/方法的参数中function get(object $user, string $name){return $user->write($name);}echo get(new class (){public function write($name){return 'Hello Hello ' . $name;}}, 'zhangsan');
本次课程老师从浅显易懂的实例出发，详解介绍了对象序列化与实战案例相关内容，通过回看视频及讲义代码，尽力理解老师列举的步步递进的层次关系与应用场景， 并通过修改实现部分代码对照差异之处，感觉收获较大。