新人Spring求教！！！！！！！

[xhw951122]

最近在学习Spring框架，自己写的一个小型信息管理系统，这里有一个异常怎么都没解决：
HTTP Status 500 - Request processing failed; nested exception is java.lang.NullPointerException

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.NullPointerException
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:656)
org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:560)
javax.servlet.http.HttpServlet.service(HttpServlet.java:650)
javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)

百度后得知是值未判空，但我已经写了判空语句，还是报这个异常，求问怎么解决