今天遇到一个问题如下，看起来像是过滤器的问题：
javax.servlet.ServletException: Filtered request failed. at org.apache.shiro.web.servlet.AbstractShiroFilter.doFilterInternal(AbstractShiroFilter.java:384) at org.apache.shiro.web.servlet.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:125) at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:344) at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:261) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at net.bull.javamelody.MonitoringFilter.doFilter(MonitoringFilter.java:201) at net.bull.javamelody.MonitoringFilter.doFilter(MonitoringFilter.java:178) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:223) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:107) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:504) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:155) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:75) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:934) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:90) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:494) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1009) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:632) at org.apache.coyote.http11.Http11NioProtocol$Http11ConnectionHandler.process(Http11NioProtocol.java:223) at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1592) at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1550) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) at java.lang.Thread.run(Thread.java:745) Caused by: java.lang.IllegalArgumentException at org.apache.catalina.webresources.AbstractResourceSet.checkPath(AbstractResourceSet.java:39) at org.apache.catalina.webresources.DirResourceSet.getResource(DirResourceSet.java:91) at org.apache.catalina.webresources.StandardRoot.getResourceInternal(StandardRoot.java:176) at org.apache.catalina.webresources.CachedResource.validate(CachedResource.java:62) at org.apache.catalina.webresources.Cache.getResource(Cache.java:78) at org.apache.catalina.webresources.StandardRoot.getResource(StandardRoot.java:163) at org.apache.catalina.core.StandardContext.getRealPath(StandardContext.java:4528) at org.apache.catalina.core.ApplicationContext.getRealPath(ApplicationContext.java:398) at org.apache.catalina.core.ApplicationContextFacade.getRealPath(ApplicationContextFacade.java:335) at com.opensymphony.module.sitemesh.mapper.FileDecoratorMapper.getNamedDecorator(FileDecoratorMapper.java:48) at com.opensymphony.module.sitemesh.mapper.AbstractDecoratorMapper.getNamedDecorator(AbstractDecoratorMapper.java:50) at com.opensymphony.module.sitemesh.mapper.AbstractDecoratorMapper.getNamedDecorator(AbstractDecoratorMapper.java:50) at com.opensymphony.module.sitemesh.mapper.AbstractDecoratorMapper.getNamedDecorator(AbstractDecoratorMapper.java:50) at com.opensymphony.module.sitemesh.mapper.PageDecoratorMapper.getByProperty(PageDecoratorMapper.java:70) at com.opensymphony.module.sitemesh.mapper.PageDecoratorMapper.getDecorator(PageDecoratorMapper.java:62) at com.opensymphony.module.sitemesh.mapper.AbstractDecoratorMapper.getDecorator(AbstractDecoratorMapper.java:45) at com.opensymphony.module.sitemesh.mapper.InlineDecoratorMapper.getDecorator(InlineDecoratorMapper.java:41) at com.opensymphony.sitemesh.compatability.DecoratorMapper2DecoratorSelector.selectDecorator(DecoratorMapper2DecoratorSelector.java:30) at com.opensymphony.sitemesh.webapp.SiteMeshFilter.doFilter(SiteMeshFilter.java:83) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.apache.shiro.web.servlet.AbstractShiroFilter.executeChain(AbstractShiroFilter.java:449) at org.apache.shiro.web.servlet.AbstractShiroFilter$1.call(AbstractShiroFilter.java:365) at org.apache.shiro.subject.support.SubjectCallable.doCall(SubjectCallable.java:90) at org.apache.shiro.subject.support.SubjectCallable.call(SubjectCallable.java:83) at org.apache.shiro.subject.support.DelegatingSubject.execute(DelegatingSubject.java:383) at org.apache.shiro.web.servlet.AbstractShiroFilter.doFilterInternal(AbstractShiroFilter.java:362) ... 29 more像这种过滤器抛出的异常，一般是被包装过的，丢失了一部分信息，通过二分法注释 web.xml 中的过滤器，就可以确定出错的过滤器。
另一个思路其实是看 Cased by 后面的第一个调用 org.apache.catalina.webresources.AbstractResourceSet.checkPath，就可以知道是 tomcat 读取项目资源路径的问题，而不是过滤器的问题，通过修改 tomcat 设置或者更换 tomcat 应该就能解决。
Webresources class AbstractResourceSet throws exception upon callong ServletContext.getRealPath(“”)
Tomcat 8, unlike Tomcat 7.0.42, throws IllegalArgumentException upon calling ServletContext.getRealPath(“”). It seems that TC8 expects that argument provided to getRealPath is non-empty string.
I believe that ServletContext.getRealPath should allow empty string as argument.
Wizzercn/NutzWk/issues/18
本地获取tomcat服务器部署路径，但真实服务器获取tomcat部署路径报错
