菜鸟求助 ssh框架 jstl

最近在自学java,ssh框架那一块
直接上代码Actonpublic ActionForward login(ActionMapping mapping, ActionForm form,
HttpServletRequest request, HttpServletResponse response) {
LoginForm loginForm = (LoginForm) form;// TODO Auto-generated method stub
UserTable userTable=new UserTable();

if(userBiz.login(loginForm.getUserTable().getUsername(), loginForm.getUserTable().getPassword())!=null){

//
List listUser=new ArrayList();
listUser=userBiz.queryUser();//显示所有信息
request.getSession().setAttribute("listUser", "listUser");
return mapping.findForward("success");
}
return mapping.getInputForward();
}Jsp页面 <c:forEach var="user" items="${listUser}" >
   
   ${user['username']}
   </c:forEach>问题2010-3-2 23:00:02 org.apache.catalina.core.StandardWrapperValve invoke
严重: Servlet.service() for servlet action threw exception
javax.el.PropertyNotFoundException: Property 'username' not found on type java.lang.String
at javax.el.BeanELResolver$BeanProperties.get(BeanELResolver.java:193)
at javax.el.BeanELResolver.property(BeanELResolver.java:267)
at javax.el.BeanELResolver.getValue(BeanELResolver.java:60)
at javax.el.CompositeELResolver.getValue(CompositeELResolver.java:53)
at org.apache.el.parser.AstValue.getValue(AstValue.java:97)
at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:186)
at org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate(PageContextImpl.java:923)
at org.apache.jsp.index_jsp._jspx_meth_c_005fforEach_005f0(index_jsp.java:116)
at org.apache.jsp.index_jsp._jspService(index_jsp.java:79)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:393)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)