{ "a": 1, "b": "3" }
curl --location --request POST '/add' \ --header 'Content-Type: application/json' \ --data-raw '{ "a": 1, "b": "3" }'
{ "code": 200, "message": "\u6dfb\u52a0\u6570\u636e\u6210\u529f\uff01" }