HTTP Status 500 -
type Exception report

message

description The server encountered an internal error that prevented it from fulfilling this request.

exception

java.lang.NullPointerException
    cn.zzw.mess.servlet.UserServlet.doPost(UserServlet.java:82)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:650)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
    cn.zzw.mess.filter.MyFilter.doFilter(MyFilter.java:27)
note The full stack trace of the root cause is available in the Apache Tomcat/7.0.69 logs.

有没有人说一下嘛！

cn.zzw.mess.servlet.UserServlet这个类，第82行报空指针错误，建议debug程序，看下具体是哪里出了问题

cn.zzw.mess.servlet.UserServlet.doPost(UserServlet.java:82) 上下代码贴出来

java.lang.NullPointerException
    cn.zzw.mess.servlet.UserServlet.doPost(UserServlet.java:82)

说明你写的UserServlet.java第82行有空指针异常的错误，你没贴出代码，具体是什么错也看不出来