通过类实现四个方法：offsetExists，offsetGet，offsetSet，offsetUnset
class ObjArray implements \ArrayAccess
{
private $testData = [
"title" => "abc",
];
public function offsetExists($key)
{
echo "offsetExists".$key;
return isset($this->testData[$key]);
}
public function offsetGet($key)
{
echo "offsetGet01".$key;
return $this->testData[$key];
}
public function offsetSet($key, $value)
{
echo "offsetSet".$key;
$this->testData[$key] = $value;
}
public function offsetUnset($key)
{
echo "offsetUnset".$key;
unset($this->testData[$key]);
}
}
调用ObjArray，如果没有实现\ArrayAccess，如下调用类，就会报错
public function obj(){
$obj = new \ObjArray();
var_dump($obj[‘title‘]);
}