Question

Below is my deployment descriptor. I’m using Spring MVC, but I’ve got a url rewrite filter in place that is supposed to run, and then forward to the appropriate controller. For some reason this filter is loading on startup, trying to get the path translated, and throwing a nullpointerexception because there is no path. I never knew filters loaded at startup, but that looks like what is happening.

<!-- SERVLETS -->

<servlet>
    <servlet-name>springmvc</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <load-on-startup>1</load-on-startup>
</servlet>

<servlet-mapping>
    <servlet-name>springmvc</servlet-name>
    <url-pattern>/index.html</url-pattern>
</servlet-mapping>

<servlet-mapping>
    <servlet-name>springmvc</servlet-name>
    <url-pattern>/</url-pattern>
</servlet-mapping>

<!-- FILTERS -->

<filter>
    <filter-name>URLRewriteFilter</filter-name>
    <filter-class>com.ecomm.filters.URLRewriteFilter</filter-class>
</filter>

<filter-mapping>
    <filter-name>URLRewriteFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

EDIT:

Aug 17, 2010 11:28:12 AM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet jsp threw exception
java.lang.NullPointerException
    at com.ecomm.helpers.TranslateURLHelper.executeController(TranslateURLHelper.java:47)
    at com.ecomm.filters.URLRewriteFilter.doFilter(URLRewriteFilter.java:41)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:215)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:172)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:174)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:879)
    at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
    at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
    at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
    at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689)
    at java.lang.Thread.run(Unknown Source)

Answer 1

It look like that you’re deploying the webapp on the ROOT context using Eclipse. The Tomcat plugin of Eclipse does indeed a self-test on startup by firing a GET request on the ROOT.

Just ignore it or fix the code so that it doesn’t throw NPE. This is IMO definitely a bug in the com.ecomm.filters.URLRewriteFilter. Empty paths should not be counted as exceptional cases. Endusers could fire them as good.