作用	代码
是否为 GET 请求	if (Request::instance()->isGet())
是否为 POST 请求	if (Request::instance()->isPost())
是否为 PUT 请求	if (Request::instance()->isPut())
是否为 DELETE 请求	if (Request::instance()->isDelete())
是否为 Ajax 请求	if (Request::instance()->isAjax())
是否为 Pjax 请求	if (Request::instance()->isPjax())
是否为手机访问	if (Request::instance()->isMobile())
是否为 HEAD 请求	if (Request::instance()->isHead())
是否为 Patch 请求	if (Request::instance()->isPatch())
是否为 OPTIONS 请求	if (Request::instance()->isOptions())
是否为 cli	if (Request::instance()->isCli())
是否为 cgi	if (Request::instance()->isCgi())