好。我真笨。否决这个问题，嘲笑我，等等。问题出在isAdmin（）委托给的方法中。该方法中存在一个空指针异常。但是，以我的辩护，我会说我所得到的堆栈跟踪有点不清楚，并使其看起来像是EL问题，而不是代码中的简单空指针。
醋，您可以保证即使没有属性，isAdmin（）仍能正常工作，这确实帮助我解决了这一问题。感谢那。
javax.el.ELException: java.lang.NullPointerException at javax.el.BeanELResolver.getValue(BeanELResolver.java:298) at javax.el.CompositeELResolver.getValue(CompositeELResolver.java:175) at com.sun.el.parser.AstValue.getValue(AstValue.java:138) at com.sun.el.ValueexpressionImpl.getValue(ValueexpressionImpl.java:206) at org.apache.jasper.runtime.PageContextImpl.evaluateexpression(PageContextImpl.java:1001) at org.apache.jsp.WEB_002dINF.jsp.managepermissions_jsp._jspx_meth_c_forEach_1(org.apache.jsp.WEB_002dINF.jsp.managepermissions_jsp:452) at org.apache.jsp.WEB_002dINF.jsp.managepermissions_jsp._jspx_meth_c_forEach_0(org.apache.jsp.WEB_002dINF.jsp.managepermissions_jsp:399) at org.apache.jsp.WEB_002dINF.jsp.managepermissions_jsp._jspx_meth_form_form_0(org.apache.jsp.WEB_002dINF.jsp.managepermissions_jsp:348) at org.apache.jsp.WEB_002dINF.jsp.managepermissions_jsp._jspService(org.apache.jsp.WEB_002dINF.jsp.managepermissions_jsp:197) at org.apache.jasper.runtime.HttpJspbase.service(HttpJspbase.java:109) at javax.servlet.http.HttpServlet.service(HttpServlet.java:802) at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:389) at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:486) at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:380) at javax.servlet.http.HttpServlet.service(HttpServlet.java:802) at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:502) at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:363) at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216) at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181) at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:766) at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:417) at org.mortbay.jetty.servlet.Dispatcher.forward(Dispatcher.java:334) at org.mortbay.jetty.servlet.Dispatcher.forward(Dispatcher.java:126) at org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:240) at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:252) at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1173) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:901) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:809) at org.springframework.web.servlet.frameworkServlet.processRequest(frameworkServlet.java:523) at org.springframework.web.servlet.frameworkServlet.doPost(frameworkServlet.java:463) at javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
