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闭包(Closure)的创建和访问与自定义异常类(Exception)的使用- PHP培训十期线上班
手机用户1576673622
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在php中，许多函数或方法的形参为callable类型, 这时，可以向这个参数传入具名函数或匿名函数。其中，匿名函数是php闭包的表示形式，为一个Closure类的实例。
下面，通过例子来演示闭包的创建和使用。

  1. //闭包类
  2. Closure {
  3.     /*方法*/
  4.     __construct ( void )
  5.     public static Closure bind (Closure $closure , object $newthis [, mixed $newscope = 'static' ])
  6.     public Closure bindTo (object $newthis [, mixed $newscope = 'static' ])
  7. }

一、创建闭包，与对象或类绑定来访问类成员

1. 创建闭包

  1. //文件名 closure\closureCreate.php
  2. namespace closure;
  4. use Closure;
  6. function closureCreate(string $name): Closure
  7. {
  8.     //创建闭包
  9.     return function (string $var) use ($name) {
  10.         return sprintf('%s%s',$name,$var);
  11.     };
  12. }
  14. $closure = closureCreate('php中文网');
  15. //使用闭包
  16. echo $closure('欢迎您！');
结果

2. 将闭包与对象或类绑定来访问类成员

  1. <?php
  2. //文件 closure\closureAccess.php
  3. namespace closure;
  5. use Closure;
  7. class closureAccess
  8. {
  9.     public $publicVar = '';
  10.     public static $staticVar = '';
  11.     private $privateVar = '';
  12.     private static $privateStaVar = '';
  13.     protected $protectedVar = '';
  14.     protected static $protectedStaVar = '';
  16.     //取不存在的值时
  17.     public function __get(string $name): string
  18.     {
  19.         //如果非静态
  20.         if (isset($this->$name)) {
  21.             return $this->$name;
  22.         }
  24.         //如果静态
  25.         if (isset(static::${$name})) {
  26.             return static::${$name};
  27.         }
  28.     }
  30.     //设置不存在的值时
  31.     public function __set(string $name, $value): void
  32.     {
  33.         //如果非静态
  34.         if (isset($this->$name)) {
  35.             $this->$name = $value;
  36.         }
  38.         //如果静态
  39.         if (isset(static::${$name})) {
  40.             static::${$name} = $value;
  41.         }
  42.     }
  44.     //把对象当字符访问时
  45.     public function __toString(): string
  46.     {
  47.         return <<<DOC
  48.         publicvar = {$this->publicVar}</br>
  49.         staticVar = {$this->staticVar}</br>
  50.         privateVar = {$this->privateVar}</br>
  51.         privateStaVar = {$this->privateStaVar}</br>
  52.         protectedVar = {$this->protectedVar}</br>
  53.         protectedStaVar = {$this->protectedStaVar}</br>
  54.         DOC;
  55.     }
  56. }
  58. //匿名函数，闭包
  59. $setter = function (string $publicVar, string $staticVar, string $privateVar, string $privateStaVar, string $protectedVar, string $protectedStaVar): void 
  60. {
  61.     //绑定 public
  62.     $this->publicVar = $publicVar;
  63.     //绑定 public static变量
  64.     static::$staticVar = $staticVar;
  65.     //绑定private变量
  66.     $this->privateVar = $privateVar;
  67.     //绑定private static变量
  68.     $this->privateStaVar = $privateStaVar;
  69.     //绑定protected 变量
  70.     $this->protectedVar = $protectedVar;
  71.     //绑定protected static 变量
  72.     $this->protectedStaVar = $protectedStaVar;
  73. };
  75. $closureAccess = new closureAccess();
  76. //既有实例也有类，双绑定
  77. // $closure=$setter->bindTo($closureAccess, closureAccess::class);
  78. $closure = Closure::bind($setter, $closureAccess, closureAccess::class);
  79. $closure('a', 'b', 'c', 'd', 'e', 'f');
  80. echo $closureAccess;
结果

编程过程中，常出现很多的错误和异常，php有专门处理错误和异常的类（Exception类），可自定义该类的__toString()方法，自定义错误或异常的输出.

二、创建自定义异常类,实现用户登录与验证流程的异常处理

1. 自定义异常类
  1. //文件src\login\LoginException.php;
  3. namespace src\login;
  5. use Exception;
  7. class LoginException extends Exception
  8. {
  9.     public function __construct($message,$previous)
  10.     {
  11.         parent :: __construct($message, $previous);
  12.     }
  14.     public function __toString(): string
  15.     {
  16.         return <<<DOC
  17.         <table border="1" cellsapcing="0" cellpadding="5">
  18.             <tr bgcolor="wheat">
  19.                 <th>错误信息</th>
  20.                 <th>代码</th>
  21.                 <th>文件</th>
  22.                 <th>行号</th>
  23.             </tr>
  24.             <tr>
  25.                 <td>$this->message</td>
  26.                 <td>$this->code</td>
  27.                 <td>$this->file</td>
  28.                 <td>$this->line</td>
  29.             </tr>
  30.             </table>
  31.         DOC;
  32.     }
  33. }
2.用户登录
  1. <?php
  2. //文件 src\login\LoginView.php
  3. namespace src\login;
  5. class LoginView
  6. {
  7.     private $action;
  8.     private $checkAction;
  9.     private $checkStyle;
  11.     public function __construct(string $action)
  12.     {
  13.         $this->action = $action;
  14.     }
  16.     //设置验证请求的内容: ....?action=login;
  17.     public function setCheckStyle(string $checkAction, string $checkStyle): void
  18.     {
  19.         $this->checkAction = $checkAction;
  20.         $this->checkStyle = $checkStyle;
  21.     }
  23.     public function loginSimple(): string
  24.     {
  25.         return <<<DOC
  26.         <!DOCTYPE html>
  27.         <html lang="en">
  28.         <head>
  29.             <meta charset="UTF-8">
  30.             <title>Document</title>
  31.         </head>
  32.         <body>
  33.             <h3>用户登录</h3>
  34.             <form action="{$this->action}?{$this->checkAction}={$this->checkStyle}" method="post">
  35.                 <div>
  36.                     <label for="name">用户名</label>
  37.                     <input type="text" id='name' name='name'>
  38.                 </div>
  39.                 <div>
  40.                     <label for="pssword">密码</label>
  41.                     <input type="password" id='password' name='password'>
  42.                 </div>
  43.                 <button>提交</button>
  44.             </form>
  45.         </body>
  46.         </html>
  47.         DOC;
  48.     }
  49. }
3.数据库准备
  1. <?php
  2. //文件 src\login\LoginModel.php;
  3. namespace src\login;
  5. use mysqli;
  7. require 'LoginAutoload.php';
  9. class LoginModel
  10. {
  11.     private $mysqli;
  13.     public function __construct(string $host, string $user, string $password, string $dbname)
  14.     {
  15.         $this->mysqli = new mysqli($host, $user, $password, $dbname);
  16.     }
  18.     public function __set(string $name, $value)
  19.     {
  20.         $this->{$name} = $value;
  21.     }
  23.     //从数据库查询数据
  24.     public function select()
  25.     {
  26.         try {
  27.             $sql = 'SELECT ' . $this->fields . ' FROM ' . $this->table . (($this->condition) ? ' WHERE ' . $this->condition : NULL) . ';';
  28.             //处理查询异常
  29.             if (!$this->mysqli->query($sql)) throw new  LoginException($sql .  '<br>查询语句有误', 303);
  30.             $result = $this->mysqli->query($sql);
  31.             return $result->fetch_all(MYSQLI_ASSOC);
  32.         } catch (LoginException $e) {
  33.             echo $e;
  34.         }
  35.     }
  36. }
4.登录验证
  1. <?php
  2. //文件 src\login\LoginControl;
  3. namespace src\login;
  5. require 'LoginAutoload.php';
  7. class LoginControl
  8. {
  9.     private $loginModel;
  10.     private $callback;
  12.     public function __construct(LoginModel $loginModel)
  13.     {
  14.         $this->loginModel = $loginModel;
  15.     }
  17.     //设置回调函数用于验证
  18.     public function setCallback(callable $callback): void
  19.     {
  20.         $this->callback = $callback;
  21.     }
  23.     //验证来源
  24.     public function checkUrl(): bool
  25.     {
  26.         $currentUrl = basename(filter_input(INPUT_SERVER, 'SCRIPT_NAME'));
  27.         //设置查询条件
  28.         $this->loginModel->condition = $this->loginModel->fields . '=\'' . $currentUrl . '\'';
  29.         try {
  30.             if (!($this->loginModel->select())) throw new LoginException('非法来源', 101);
  31.             echo '合法来源';
  32.             return true;
  33.         } catch (LoginException $e) {
  34.             echo $e;
  35.             return false;
  36.         }
  37.     }
  39.     //检查请求内容
  40.     public function checkAction($checkAction): bool
  41.     {
  42.         $action = filter_input(INPUT_GET, $checkAction, FILTER_SANITIZE_STRING);
  43.         //设置查询条件
  44.         $this->loginModel->condition = $this->loginModel->fields . '=\'' . strtolower($action) . '\'';
  45.         //如果请求内容不匹配，提示
  46.         try {
  47.             if (!($this->loginModel->select())) throw new LoginException('<br>无需验证', 305);
  48.             echo '<br>须验证:' . $checkAction;
  49.             return true;
  50.         } catch (LoginException $e) {
  51.             echo '<br>' . $e->getMessage();
  52.             return false;
  53.         }
  54.     }
  56.     //验证POST请求
  57.     public function checkPost(): bool
  58.     {
  59.         $check = function ($res) {
  60.             try {
  61.                 //如果验证条件有异常
  62.                 if (!$res) throw new LoginException('验证不通过', 102);
  63.                 //设置cookie;
  64.                 setcookie('user', $res);
  65.                 exit('<script>alert("验证通过");</script>');
  66.             } catch (LoginException $e) {
  67.                 echo $e;
  68.                 exit('<script>alert("' . $e->getMessage() . '");</script>');
  69.             }
  70.         };
  72.         //请求是否合法
  73.         try {
  74.             if (!(filter_input(INPUT_SERVER, 'REQUEST_METHOD') === 'POST')) throw new LoginException('<br>非法请求', 101);
  75.             echo "<br>合法请求";
  76.             $check(call_user_func_array($this->callback, [$this->loginModel]));
  77.             return true;
  78.         } catch (LoginException $e) {
  79.             echo $e;
  80.             return false;
  81.         }
  82.     }
  83. }
  85. //数据库
  86. $localhost = 'db.io';
  87. $user = 'root';
  88. $password = 'root';
  89. $dbname = 'phpedu';
  90. $loginModel = new LoginModel($localhost, $user, $password, $dbname);
  92. $loginModel->fields = '`url`';
  93. $loginModel->table = '`urls`';
  94. $loginControl = new LoginControl($loginModel);
  96. //验证来源是否合法
  97. //SELECT `url` FROM `urls` WHERE `url`='LoginControl.php';
  98. if (!$loginControl->checkUrl()) return;
  100. //检查是否需要验证login
  101. //LoginContro.php?action=login
  102. $loginModel->fields = '`action`';
  103. $loginModel->table = '`actions`';
  104. if (!$loginControl->checkAction('action')) return;
  106. //验证`name`和`password`;
  107. $loginModel->fields = '`name`, `password`';
  108. //验证`name`和`password`是否在数据库中
  109. //传入验证内容的匿名函数,
  110. $loginControl->setCallback(function (LoginModel $mysqli)
  111. {
  112.     $name = filter_input(INPUT_POST, 'name');
  113.     $password = sha1(filter_input(INPUT_POST, 'password'));
  114.     //查找 SELECT `password` FROM `users` WHERE `name`='小龙女';
  115.     $mysqli->fields = "`password`";
  116.     $mysqli->condition = "`name`='{$name}'";
  117.     $mysqli->table = '`users`';
  118.     //处理查询异常
  119.     try {
  120.         if (!$mysqli->select()) throw new LoginException('查询失败', 305);
  121.         foreach ($mysqli->select() as $val) {
  122.             if ($val['password'] === $password) {
  123.                 return $name;
  124.             }
  125.         }
  126.     } catch (LoginException $e) {
  127.         echo $e;
  128.     }
  129. });
  131. //验证POST请求,
  132. //如果`name`和`password`在数据库中，则setcookie,否则提示验证失败
  133. $loginControl->checkPost();
5.自动加载
  1. <?php
  2. //文件login/LoginAutoload.php
  4. namespace src\login;
  6. spl_autoload_register(function($class)
  7. {
  8.     $prefix=__DIR__;
  9.     $arr=explode("\\",$class);
  10.     $file=$prefix."\\". $arr[count($arr)-1] . '.php';
  11.     $file = str_replace("\\", DIRECTORY_SEPARATOR, $file);
  12.     file_exists($file) ? require $file : "文件不存在，加载失败";
  13. });
6.调用
  1. <?php
  2. //文件 src\login\LoginMain.php;
  4. namespace src\login;
  6. require 'LoginAutoload.php';
  8. $loginView=new LoginView('LoginControl.php');
  9. $loginView->setCheckStyle('action','login');
  10. echo $loginView->loginSimple();
用到的数据库phpedu3个表: users, urls, actions
1.users

2.urls

3.actions

结果
1. 密码错误时



2. 密码正确时



3. 用户不存在时



总结

1.闭包：闭包可以将一个执行环境(父级中的变量/状态)封闭到匿名函数中;常用于作为函数/方法的回调参数。闭包是一个对象，是Closure类的实例;可以把外部数据封闭到闭包中保存，也可以将闭包绑定到对象/类上，实现对属性的更新操作;
2.异常：与错误机制相比，异常处理机制主动抛出，更加主动和灵活；有时异常并不一定发生了错误，所以异常应用范围更广；通常并不会直接使用系统的异常类，而是自定义一个异常类

Correcting teacher：天蓬老师天蓬老师

Correction status：qualified

Teacher's comments：几乎所有的语言都支持匿名函数, 但并不是所有的匿名函数都是闭包, 闭包的形成有一定的条件, 这个要注意
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