求助大家看看这个错误怎么解决

Question

2011/09/01 09:38:44:796 CST [ERROR] [jsp] - Servlet.service() for servlet jsp threw exception <java.lang.NullPointerException>java.lang.NullPointerException
at com.fulong.taglib.common.PagerTag.doStartTag(PagerTag.java:181)
at org.apache.jsp.cms.manage.contents_jsp._jspx_meth_fulong_pager_0(org.apache.jsp.cms.manage.contents_jsp:873)
at org.apache.jsp.cms.manage.contents_jsp._jspService(org.apache.jsp.cms.manage.contents_jsp:668)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:322)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:291)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:672)
at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:463)
at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:398)
at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:301)
at org.apache.struts.action.RequestProcessor.doForward(RequestProcessor.java:1063)
at org.apache.struts.action.RequestProcessor.processForwardConfig(RequestProcessor.java:386)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:229)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1194)
at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:360)
at org.springframework.security.intercept.web.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:109)
at org.springframework.security.intercept.web.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:83)
at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:372)
at org.springframework.security.ui.ExceptionTranslationFilter.doFilterHttp(ExceptionTranslationFilter.java:113)
at org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:50)
at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:372)
at org.springframework.security.ui.rememberme.RememberMeProcessingFilter.doFilterHttp(RememberMeProcessingFilter.java:124)
at org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:50)
at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:372)
at org.springframework.security.wrapper.SecurityContextHolderAwareRequestFilter.doFilterHttp(SecurityContextHolderAwareRequestFilter.java:91)
at org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:50)
at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:372)
at org.springframework.security.ui.digestauth.DigestProcessingFilter.doFilter(DigestProcessingFilter.java:328)
at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:372)
at org.springframework.security.context.HttpSessionContextIntegrationFilter.doFilterHttp(HttpSessionContextIntegrationFilter.java:241)
at org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:50)
at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:372)
at org.springframework.security.util.FilterChainProxy.doFilter(FilterChainProxy.java:174)
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:183)
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:138)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at com.fulong.common.servlet.CharacterEncodingFilter.doFilter(CharacterEncodingFilter.java:64)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:856)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:744)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
at java.lang.Thread.run(Thread.java:619)

Answer 1

传到页面的值为空，debug一下看看

Answer 2

没找到问题在哪里。debug不太会用，concole里打印出来的错误信息也不太会读

Answer 3

java.lang.NullPointerException
at com.fulong.taglib.common.PagerTag.doStartTag(PagerTag.java:181) 错误很明显啊、这用的是什么标签？

Answer 4

建议！楼主可以调试呀，可以利用IE8和Eclipse的调试结合找出问题，不调试是很难找到具体是那个标签出错了的！

Answer 5

很明显是空指针错误，你要看下是不是有些对象使用到了他的方法，这个对象却是NULL