Token, which means "token", is a string of strings generated by the server as the identification of the client request.

When a user logs in for the first time, the server generates a token and returns it to the client. In the future, the client only needs to bring this token to request data, and no user name and password are needed. Composition of simple token; Uid (user's unique identification), time (timestamp of current time), sign (signature), hexadecimal string of a certain length compressed by hash algorithm. To prevent token leakage).