trimFilter & UrlRewriteFilter causing IllegalStateException

Question

I am using trimFilter (com.cj.trim.trimFilter) to strip all the empty lines & spaces created in my output and UrlRewriteFilter to perform seo friendly URLs.

Many pages work fine, but some throw the below exception java.lang.IllegalStateException: getWriter() has already been called for this response

Stacktrace [2015-02-19T00:06:49.718+0000] [glassfish 4.1] [WARNING] [] [javax.enterprise.web] [tid: _ThreadID=49 _ThreadName=jk_listener(1)] [timeMillis: 1424304409718] [levelValue: 900] [[ StandardWrapperValve[default]: Servlet.service() for servlet default threw exception java.lang.IllegalStateException: getWriter() has already been called for this response at org.apache.catalina.connector.Response.getOutputStream(Response.java:746) at org.apache.catalina.connector.ResponseFacade.getOutputStream(ResponseFacade.java:206) at javax.servlet.ServletResponseWrapper.getOutputStream(ServletResponseWrapper.java:142) at javax.servlet.ServletResponseWrapper.getOutputStream(ServletResponseWrapper.java:142) at com.cj.trim.trimFilter.doFilter(Unknown Source) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214) at org.tuckey.web.filters.urlrewrite.RuleChain.handleRewrite(RuleChain.java:176) at org.tuckey.web.filters.urlrewrite.RuleChain.doRules(RuleChain.java:145) at org.tuckey.web.filters.urlrewrite.UrlRewriter.processRequest(UrlRewriter.java:92) at org.tuckey.web.filters.urlrewrite.UrlRewriteFilter.doFilter(UrlRewriteFilter.java:394) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214) at org.apache.catalina.core.ApplicationDispatcher.doInvoke(ApplicationDispatcher.java:873) at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:739) at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:575) at org.apache.catalina.core.ApplicationDispatcher.doDispatch(ApplicationDispatcher.java:546) at org.apache.catalina.core.ApplicationDispatcher.dispatch(ApplicationDispatcher.java:428) at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:378) at org.tuckey.web.filters.urlrewrite.NormalRewrittenUrl.doRewrite(NormalRewrittenUrl.java:213) at org.tuckey.web.filters.urlrewrite.RuleChain.handleRewrite(RuleChain.java:171) at org.tuckey.web.filters.urlrewrite.RuleChain.doRules(RuleChain.java:145) at org.tuckey.web.filters.urlrewrite.UrlRewriter.processRequest(UrlRewriter.java:92) at org.tuckey.web.filters.urlrewrite.UrlRewriteFilter.doFilter(UrlRewriteFilter.java:394) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:316) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:160) at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:734) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:673) at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:99) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:174) at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:415) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:282) at com.sun.enterprise.v3.services.impl.ContainerMapper$HttpHandlerCallable.call(ContainerMapper.java:459) at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:167) at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:201) at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:175) at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:235) at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119) at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:284) at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:201) at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:133) at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:112) at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77) at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:561) at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:112) at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:117) at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:56) at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:137) at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:565) at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:545) at java.lang.Thread.run(Thread.java:745)

I understand that one is overlapping with other. Therefore this issue is caused. I need to know how to get this issue fixed. Where should I change the code to solve this issue.

Answer 1

trimFilter & UrlRewriteFilter are clashing with each other & that's why it wasn't working in some JSP's.

All I did is removed trimFilter & instead use the below configuration in web.xml

   <jsp-config>
  <jsp-property-group>
<url-pattern>*.jsp</url-pattern>
<trim-directive-whitespaces>true</trim-directive-whitespaces>
 </jsp-property-group>
</jsp-config>

Now problem solved.

Answer 2

I think you are trying to get the writer at one place and again the outputstream later on. Like response.getWriter(); at one place and response.getOutputStream(); at another place

You cannot use both of them the same time.

Check the javadocs, they have mentioned about it.

http://docs.oracle.com/javaee/5/api/javax/servlet/ServletResponse.html#getWriter%28%29

PrintWriter getWriter() throws IOException

Returns a PrintWriter object that can send character text to the client. The PrintWriter uses the character encoding returned by getCharacterEncoding(). If the response's character encoding has not  been specified as described in getCharacterEncoding (i.e., the method  just returns the default value ISO-8859-1), getWriter updates it to ISO-8859-1.

Calling flush() on the PrintWriter commits the response.

Either this method or getOutputStream() may be called to write the body, not both.