Spring Security

  	 <%   
                if (session.getAttribute(UsernamePasswordAuthenticationFilter.SPRING_SECURITY_LAST_EXCEPTION_KEY) != null) {   
                
 %>  
           <span style="color:red"> 登录失败，请重试. </span>  
            <%   
                }   
            %>  

<script language="JavaScript">    
<!--    
	if ("<%= request.getParameter("error")%>" == "true") {   
		alert("invalid username/password" );   
	}
//-->    
</script>   
</html>

<SCRIPT type="text/javascript">
		<!--
    	alert ("${sessionScope['SPRING_SECURITY_LAST_USERNAME']}" + ";" + "${sessionScope.userRole}");
//    alert(<sec:authentication property="name"/> + ";" + <sec:authentication property="principal.username"/>);
    	<%
    User user = (User) SecurityContextHolder.getContext().getAuthentication().getPrincipal();
    %>
    alert("<%=user.getRoles().toString()%>");

    //-->
    </SCRIPT>