Reg : Jasper Exception

Question

Hi ,
I am deploying an application in a test env which is working perfectly in our dev environment and which doesnt need any code changes.I am getting an exception while deploying.The same code is working in our dev environment.
Please help me in this.Thanks in advance.
Mar 8, 2009 3:45:32 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet jsp threw exception
java.lang.NullPointerException
     at org.apache.jsp.index_jsp._jspInit(index_jsp.java:103)
     at org.apache.jasper.runtime.HttpJspBase.init(HttpJspBase.java:52)
     at org.apache.jasper.servlet.JspServletWrapper.getServlet(JspServletWrapper.java:159)
     at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:329)
     at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
     at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
     at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
     at com.core.test.test1.CachePreventionFilter.doFilter(CachePreventionFilter.java:42)
     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:175)
     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:263)
     at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
     at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:584)
     at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
     at java.lang.Thread.run(Unknown Source)

Answer 1

What happens when i copy and paste the jar file in my application's lib directory?What happens is that you have the classes appearing twice in your class path.
It will normally use the first version of the class that it comes across.
For a web application, the Standard Tomcat resolution order is something like
WEB-INF/classes
jar files in WEB-INF/lib (alphabetical order of filename)
jar files in [TOMCAT]/shared/lib
jar files in [TOMCAT]/common/lib
If it finds it in one of the earlier spots, it won't go looking further.
For the server itself, the classpath is just the [TOMCAT]/common/lib and [TOMCAT]/server/lib directories.
Thus jsp-api is in two different places - and will be retrieved from the two different places depending upon who is doing the loading - the web app or the server.
As you have found, this can lead to issues.
Bottom line - don't have servlet-api.jar, jsp-api.jar (or any other of the servlet classes) in your WEB-INF/lib directory.
In fact if you can eliminate duplicate classes entirely from your classpath, you can prevent a lot of issues.