Error 500--Internal Server Error

java.lang.ArithmeticException: / by zero
	at inet.controller.GioiThieuController.handleRequestInternal(GioiThieuController.java:30)
	at org.springframework.web.servlet.mvc.AbstractController.handleRequest(AbstractController.java:154)
	at org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter.handle(SimpleControllerHandlerAdapter.java:50)
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:945)
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:876)
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:961)
	at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:852)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:844)
	at weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:280)
	at weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:254)
	at weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.java:136)
	at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:346)
	at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:243)
	at weblogic.servlet.internal.RequestDispatcherImpl.invokeServlet(RequestDispatcherImpl.java:587)
	at weblogic.servlet.internal.RequestDispatcherImpl.forward(RequestDispatcherImpl.java:273)
	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 weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:79)
	at inet.trimfilter.ReplaceHTMLFilter.doFilter(ReplaceHTMLFilter.java:42)
	at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:79)
	at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.wrapRun(WebAppServletContext.java:3436)
	at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:3402)
	at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321)
	at weblogic.security.service.SecurityManager.runAs(SecurityManager.java:120)
	at weblogic.servlet.provider.WlsSubjectHandle.run(WlsSubjectHandle.java:57)
	at weblogic.servlet.internal.WebAppServletContext.doSecuredExecute(WebAppServletContext.java:2285)
	at weblogic.servlet.internal.WebAppServletContext.securedExecute(WebAppServletContext.java:2201)
	at weblogic.servlet.internal.WebAppServletContext.execute(WebAppServletContext.java:2179)
	at weblogic.servlet.internal.ServletRequestImpl.run(ServletRequestImpl.java:1572)
	at weblogic.servlet.provider.ContainerSupportProviderImpl$WlsRequestExecutor.run(ContainerSupportProviderImpl.java:255)
	at weblogic.work.ExecuteThread.execute(ExecuteThread.java:311)
	at weblogic.work.ExecuteThread.run(ExecuteThread.java:263)