java中，项目跑起来了，但是进入登录界面的时候出现如下报错，找不到具体原因

Question

2017-11-6 15:10:34 org.apache.catalina.core.StandardWrapperValve invoke
严重: Servlet.service() for servlet jsp threw exception
java.lang.NullPointerException
at org.apache.jsp.index_jsp._jspInit(index_jsp.java:23)
at org.apache.jasper.runtime.HttpJspBase.init(HttpJspBase.java:52)
at org.apache.jasper.servlet.JspServletWrapper.getServlet(JspServletWrapper.java:164)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:340)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:723)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.yss.xbrl.filter.ForwardFilter.doFilter(ForwardFilter.java:53)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:879)
at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:617)
at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1760)
at java.lang.Thread.run(Thread.java:662)

Answer 1

HTTP Status 500 - java.lang.NullPointerException

---

type Exception report

message java.lang.NullPointerException

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

exception

org.apache.jasper.JasperException: java.lang.NullPointerException
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:538)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:370)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
javax.servlet.http.HttpServlet.service(HttpServlet.java:723)
com.yss.xbrl.filter.ForwardFilter.doFilter(ForwardFilter.java:53)

root cause

java.lang.NullPointerException
org.apache.jsp.index_jsp._jspInit(index_jsp.java:23)
org.apache.jasper.runtime.HttpJspBase.init(HttpJspBase.java:52)
org.apache.jasper.servlet.JspServletWrapper.getServlet(JspServletWrapper.java:164)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:340)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
javax.servlet.http.HttpServlet.service(HttpServlet.java:723)
com.yss.xbrl.filter.ForwardFilter.doFilter(ForwardFilter.java:53)

note The full stack trace of the root cause is available in the Apache Tomcat/6.0.37 logs.