流只能用一次

处理HttpServletRequest请求时，请求里面的参数只能使用一次，不能复用。

https://blog.youkuaiyun.com/qq_34019552/article/details/110855319

http://www.cppblog.com/wing/archive/2011/07/21/151545.aspx

https://www.jb51.net/article/220463.htm

https://blog.youkuaiyun.com/xianzhen376/article/details/49663621

https://hongjiang.info/http-application-x-www-form-urlencoded/

https://www.cnblogs.com/liangjie/archive/2011/05/25/2057399.html