简介提供像访问数组一样访问对象的能力的接口。

接口摘要

ArrayAccess {/* 方法 */abstract public boolean offsetExists ( mixed $offset )abstract public mixed offsetGet ( mixed $offset )abstract public void offsetSet ( mixed $offset , mixed $value )abstract public void offsetUnset ( mixed $offset )}

目录ArrayAccess::offsetExists — 检查一个偏移位置是否存在ArrayAccess::offsetGet — 获取一个偏移位置的值ArrayAccess::offsetSet — 设置一个偏移位置的值ArrayAccess::offsetUnset — 复位一个偏移位置的值

代码演示

class Obj implements ArrayAccess{ private $container = []; public function offsetExists($offset): bool { echo '调用' . __METHOD__ . '方法' . PHP_EOL; echo print_r(func_get_args(), true); return isset($this->container[$offset]); } public function offsetGet($offset) { echo '调用' . __METHOD__ . '方法' . PHP_EOL; echo print_r(func_get_args(), true); return $this->container[$offset] ?? null; } public function offsetSet($offset, $value) { echo '调用' . __METHOD__ . '方法' . PHP_EOL; echo print_r(func_get_args(), true); $this->container[$offset] = $value; } public function offsetUnset($offset) { echo '调用' . __METHOD__ . '方法' . PHP_EOL; echo print_r(func_get_args(), true); unset($this->container[$offset]); }}//实例化对象$zhangsan = new Obj();//赋值$zhangsan['name'] = '张三';//调用Obj::offsetSet方法//输出echo $zhangsan['name'] . PHP_EOL;//调用Obj::offsetGet方法//校验是否存在isset($zhangsan['name']) . PHP_EOL;//调用Obj::offsetExists方法//删除数组单元unset($zhangsan['name']);//调用Obj::offsetUnset方法逆向思考：

通过调用接口方法来实现对对象属性进行操作，然后使用数组的方式访问

$zhangsan=new Obj();if ($zhangsan instanceof \ArrayAccess) { //通过调用接口方法为对象赋值 $zhangsan->offsetSet('name', '张三'); //通过数组方式取值 echo $zhangsan['name'] . PHP_EOL; //通过调用接口方法取值 echo $zhangsan->offsetGet('name').PHP_EOL; //通过调用接口方法来判断对象属性是否存在 if (!$zhangsan->offsetExists('age') && !isset($zhangsan['age'])) { $zhangsan->offsetSet('age', '18'); } $zhangsan['address']='北京'; //通过调用接口方法来判断对象属性 $zhangsan->offsetUnset('address'); echo $zhangsan['address'] ?? 'address is not exists'; //直接为对象属性赋值（不可行） $zhangsan->school='Peking University'; echo $zhangsan['school'] ?? 'school is not exists';//school is not exists}

应用案例演示

实现配置文件信息读取

按照一下给出的目录结构建立文件

./├── config│   ├── app.php│   └── database.php└── config.php

./config/app.php

<?phpreturn [ 'name' => 'app name', 'version' => 'v1.0.0'];

./config/database.php

<?phpreturn [ 'mysql' => [ 'host' => 'localhost', 'user' => 'root', 'password' => '12345678' ]];./config.php

<?phpnamespace Config;final Class Config implements \ArrayAccess{ private $config = []; private static $instance = null; private $path = null; private function __construct() { $this->path = __DIR__ . '/config/'; } //单例模式获取实例 public static function getInstance() { if (!self::$instance instanceof self) { self::$instance = new self; } return self::$instance; } //防止被克隆 private function __clone() { } public function offsetExists($offset) { return isset($this->config[$offset]); } public function offsetGet($offset) { if (!isset($this->config[$offset]) || empty($this->config[$offset])) { //装载配置文件 $this->config[$offset] = require $this->path . $offset . '.php'; } return $this->config[$offset]; } public function offsetSet($offset, $value) { throw new \Exception('不提供设置配置'); } public function offsetUnset($offset) { throw new \Exception('不提供删除配置'); }}$config = Config::getInstance();//获取app.php 文件的 nameecho $config['app']['name'].PHP_EOL; //app name//获取database.php文件mysql的user配置echo $config['database']['mysql']['user'].PHP_EOL; // root