现在java后台，只要修改一点点代码，前段页面就报500，必须重新登录才行？

Question

哪怕是加一行注释，前段也一刷新也会报500错误，必须重新登录系统才行，以前的时候没问题呀？

message 

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

exception 

org.apache.jasper.JasperException
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:372)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:802)


root cause 

java.lang.NullPointerException
    org.apache.jsp.trade.home.qdmenu.menu001_jsp._jspService(menu001_jsp.java:324)
    org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:324)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:802)


note The full stack trace of the root cause is available in the Apache Tomcat/5.0.28 logs.

Answer 1

这是报了空指针，针对你所说的 重新登录就行了 的情况，大概率是页面需要鉴权之类的操作，考虑到多数这类操作是依赖 session 或是 model 来做，所以你需要检查你页面上引起空指针的地方是否使用了这类参数、变量。

Answer 2

https://zeroturnaround.com/so... 了解一下