当我尝试使用样式表时遇到问题，它给了我这个错误：
07-Jul-2015 16:06:53.811 INFO [http-apr-8084-exec-7] mx.com.vw.servlet.filters.StylizerFilter.doFilter Stylizing: xslt/semaphore.xsl with download: false filename:null mimetype:text/html
---
CONSULTA
(Ubicación del error desconocida)java.net.MalformedURLException
java.lang.NullPointerException
at mx.com.vw.servlet.filters.StylizerFilter.doFilter(StylizerFilter.java:120)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:617)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:668)
at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2463)
at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2452)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)
在我的索引中，我要求servlet的结果并应用这个样式表，sintax是这样的：
<iframe src="${pageContext.request.contextPath}/semaphore?cmd=retrieve&stylesheet=xslt/semaphore.xsl"
width="100%" height="100%"
scrolling="auto" frameborder="0"></iframe>
如果我没有通过&stylesheet=xslt/semaphore.xsl部分，我得到的结果显然没有风格，这就是为什么我认为它与我的xsl有关，有趣的是我跑得很好同样应用程序使用tomcat 6，这是与tomcat 8。
我正在使用的tomcat版本有问题吗？
我也在使用Xalan 2.7
有什么想法吗？