Whitelabel Error Page

This application has no explicit mapping for /error, so you are seeing this as a fallback.

Sun Oct 20 17:44:00 CST 2019 There was an unexpected error (type=Bad Request, status=400). Required String parameter 'username' is not present   4开头 是客户端错误（）Bad Request 错误的请求：数据不对 Required String parameter 'username' is not present 提交的username不存在