public function cache($key = true, $expire = null, $tag = null)
{
// 增加快捷调用方式 cache(10) 等同于 cache(true, 10)
if (is_numeric($key) && is_null($expire)) {
$expire = $key;
$key = true;
}
if (false !== $key) {
$this->options['cache'] = ['key' => $key, 'expire' => $expire, 'tag' => $tag];
}
return $this;
}