struts 登录怎样alert出错误信息出来呢
struts   登录怎样alert出错误信息出来呢
？
要有消息框弹出提示的.

------解决方案--------------------
这个容易，你会写JS的把
我的public ActionForward execute(
ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response) {

AdminLoginForm adminlog=(AdminLoginForm)form;
try {
//User user = this.serviceLocator.getUserService().login(this.username, this.password);
CheckUserModule module=new CheckUserModule();
module.setName(adminlog.getUsername());
module.setPassword(adminlog.getPassword());

List list=userManager.getListByName(module);

//判断用户名是否为空
if(list==null||list.size()==0){
throw new UsernameNotExistException(adminlog.getUsername());
}
Users user=(Users)list.get(0);
module.setId(user.getUserid());
LoginUserModel loginUserModel=new LoginUserModel();
loginUserModel.setName(user.getUsername());
loginUserModel.setPassword(user.getPassword());


if (user.getPassword().equalsIgnoreCase(adminlog.getPassword())) {


List RolemoduleList=new ArrayList();



//取得SESSION把用户的信息放入session
HttpSession session = request.getSession(false);
session.setAttribute( "authorization ",loginUserModel);
session.setAttribute( "userDetail ",user);
//写日志
try{
String userip = request.getRemoteAddr();
Logger optlogger = Logger.getLogger( "OpterateLog. " + ". " + user.getName()+ ". " + userip);
Logger syslogger = Logger.getLogger( "SystemLog. " + "后台用户登录 ");

}catch(Exception e){
e.printStackTrace();
// String msg = "写日志异常 ";
// FacesUtils.addErrorMessage(msg + ", 请联系管理员。 ");
// return NavigationResults.RETRY;
}
return mapping.findForward(SUCCESS);

}
else {

String msg = "密码错误, 请重试。 ";
request.setAttribute( "msg ",msg);
request.setAttribute( "username ",adminlog.getUsername());
return mapping.findForward(ERROR);
}
}catch(UsernameNotExistException ue){
ue.printStackTrace();
String msg = "不存在的用户名, 请重试。 ";
request.setAttribute( "msg ",msg);
request.setAttribute( "username ",adminlog.getUsername());
return mapping.findForward(ERROR);
}
catch (Exception e) {
e.printStackTrace();
String msg = "系统发生异常, 请联系管理员。 ";
request.setAttribute( "msg ",msg);
request.setAttribute( "username ",adminlog.getUsername());
return mapping.findForward(ERROR);
}

}
------解决方案--------------------
通过forward以后，在request中会保存一个 "msg "的值，你在页面中用js进行判断一下应该就可以了吧！
------解决方案--------------------
public ActionForward execute(ActionMapping mapping, ActionForm form,
HttpServletRequest request, HttpServletResponse response) {
LoginForm loginForm = (LoginForm) form;
String username = loginForm.getUsername();
String userpwd = loginForm.getUserpwd();
response.setCharacterEncoding( "gbk ");
HttpSession session=request.getSession();
String validate= " ";
List list = null;
String realname = " ";
String departmentname = " ";
Str