After content has been committed?
Is there a proper way to write an error page, so that it will work
even when the response has already been committed?
There seems to be a bug or inconsistency in how tomcat handles the error page.
In Tomcat 6.0.20, if I define my error page like this in web.xml:
<error-page>
<exception-type>java.lang.Exception</exception-type>
<location>/unexpectedErrors.jsp</location>
</error-page>
Then, if the response has already been committed, Tomcat does this on
the system console:
Feb 1, 2010 5:59:04 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet jsp threw exception
java.lang.NullPointerException
at org.apache.jsp.cpe_jsp._jspService(cpe_jsp.java:693)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:374)
at
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at
com.eaglecreektech.expedience.provisioning.web.servletFilters.AuthFilter.doFilter(AuthFilter.java:133)
at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at
com.eaglecreektech.expedience.provisioning.web.servletFilters.RequestVolumeFilter.doFilter(RequestVolumeFilter.java:141)
at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at
com.eaglecreektech.expedience.provisioning.web.servletFilters.StartupCheckFilter.doFilter(StartupCheckFilter.java:65)
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:128)
at
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
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.Http11Processor.process(Http11Processor.java:849)
at
org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
at
org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:454)
at java.lang.Thread.run(Thread.java:619)
Feb 1, 2010 5:59:04 PM org.apache.catalina.core.StandardHostValve custom
SEVERE: Exception Processing
ErrorPage[exceptionType=java.lang.Exception,
location=/unexpectedErrors.jsp]
java.lang.IllegalStateException: Cannot reset buffer after response
has been committed
at org.apache.catalina.connector.Response.resetBuffer(Response.java:691)
at
org.apache.catalina.core.StandardHostValve.custom(StandardHostValve.java:409)
at
org.apache.catalina.core.StandardHostValve.throwable(StandardHostValve.java:271)
at
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
at
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
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.Http11Processor.process(Http11Processor.java:849)
at
org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
at
org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:454)
at java.lang.Thread.run(Thread.java:619)
And it doesn't put any error text into the broken page - the page just
shows how ever far it got before it encountered the error.
This behavior doesn't seem correct - it seems like it should at least
behave the same way as it does when the error page is defined in a jsp
page:
For example:
<%@ page errorPage="unexpectedErrors.jsp" %>
If the response has already been committed, then it just appends the
error page onto the end of the response (really ugly, but at least it
doesn't cause a secondary error)
If the response has not been committed, it clears the buffer and
writes the error page (which looks nice and pretty , like it should)
So, in summary:
1) - Is Tomcats handling of an error page defined in web.xml broken
when a response has already been committed?
2) - Is there anything I can do to force the browser to a proper error
page after a response has been committed?
Thanks,
Dan
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