qatang qatang - 3 years ago 167
Java Question

Can I use RedirectAttributes or FlashMap in Interceptor of Spring MVC

I have an interceptor to handle the user session. If the

user
attribute does not exist, then the interceptor will redirect to the signin page. I want to send a
session timeout
message with the redirect url, but I don't want the message in the url. I google a lot for the
RedirectAttributes
or
FlashMap
, but I can't find any good solution.

public class UserSessionInterceptor extends HandlerInterceptorAdapter {
protected final Logger logger = LoggerFactory.getLogger(this.getClass());

@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
User user = (User)request.getSession().getAttribute(CommonConstants.USER_SESSION_KEY);
if (user == null) {
String msg = String.format("session timeout");
logger.error(msg);

// response.sendRedirect("/signin?errorMessage=" + msg); //I don't want to do this..

return false;
}

return true;
}
}


signinController snippet:

@Controller
@SessionAttributes(CommonConstants.KAPTCHA_SESSION_KEY)
public class SigninController extends BaseController {

@RequestMapping(value = "/signin", method = RequestMethod.GET)
public String signinPage() {
return "forward:/index.jsp";
}

@RequestMapping(value = "/signin", method = RequestMethod.POST)
public String signin(UserForm userForm, @ModelAttribute(CommonConstants.KAPTCHA_SESSION_KEY) String captchaExpected, RedirectAttributes redirectAttributes, HttpServletRequest request) {
userForm.setCaptchaExpected(captchaExpected);
try {
loginValidator.validate(userForm);
} catch (ValidateFailedException e) {
logger.error(e.getMessage(), e);
redirectAttributes.addFlashAttribute(ERROR_MESSAGE_KEY, e.getMessage());
return "redirect:/signin";
}

User user = userService.getByUsername(userForm.getUsername());
if (user == null || !user.getPassword().equals(DigestUtils.md5Hex(userForm.getPassword()))) {
redirectAttributes.addFlashAttribute(ERROR_MESSAGE_KEY, "username or password is invalid");
return "redirect:/signin";
}
request.getSession().setAttribute(CommonConstants.USER_SESSION_KEY, user);
return "redirect:/dashboard";
}
}


index.jsp snippet:

<%@page contentType="text/html; charset=utf-8"%>
<%@ include file="/WEB-INF/jsp/include.jsp" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>welcome</title>
<meta http-equiv="pragma" content="no-cache" />
<meta http-equiv="keywords" content="" />
<meta http-equiv="description" content="" />
<link rel="shortcut icon" href="favicon.ico" type="image/x-icon" />
<link rel="stylesheet" href="${ctx}/css/bootstrap.min.css">
<link rel="stylesheet" href="${ctx}/css/main.css">
<script src="${ctx}/js/jquery-1.11.1.min.js"></script>
<script src="${ctx}/js/bootstrap.min.js"></script>
</head>
<body>
<div class="container">
<div class="login-box text-center" >
<div class="login-single-panel-header">
<h5 style="color:red">${errorMessage}</h5>
</div>
</div>
</div>
</body>
</html>


Thank you very much!

Answer Source

I just encountered the same problem. I debuged the spring source code,looking for how spring mvc same the flashmap attributes,and came up with that it same flashmap attributes in sessions.

here is my last solution:

// create a flashmap
FlashMap flashMap = new FlashMap();

// store the message
flashMap.put("ERROR_MESSAGE", "this is the message");

// create a flashmapMapManger with `request`
FlashMapManager flashMapManager = RequestContextUtils.getFlashMapManager(request);

// save the flash map data in session with falshMapManager
flashMapManager.saveOutputFlashMap(flashMap, request, response);
  • the code above referd the method org.springframework.web.servlet.view.RedirectView#renderMergedOutputModel,you may check it youself

wish this will help you!

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