java - 如何在 Spring MVC 3.1 中重定向后读取 flash 属性？

Question

我想知道在 Spring MVC 3.1 中重定向后如何读取 flash 属性。

我有以下代码:

@Controller
@RequestMapping("/foo")
public class FooController {

  @RequestMapping(value = "/bar", method = RequestMethod.GET)
  public ModelAndView handleGet(...) {
    // I want to see my flash attributes here!
  }

  @RequestMapping(value = "/bar", method = RequestMethod.POST)
  public ModelAndView handlePost(RedirectAttributes redirectAttrs) {
    redirectAttrs.addFlashAttributes("some", "thing");
    return new ModelAndView().setViewName("redirect:/foo/bar");
  }

}

我错过了什么？

Answer 1

使用Model，它应该有预填充的flash属性:

@RequestMapping(value = "/bar", method = RequestMethod.GET)
public ModelAndView handleGet(Model model) {
  String some = (String) model.asMap().get("some");
  // do the job
}

或者，您也可以使用 RequestContextUtils#getInputFlashMap :

@RequestMapping(value = "/bar", method = RequestMethod.GET)
public ModelAndView handleGet(HttpServletRequest request) {
  Map<String, ?> inputFlashMap = RequestContextUtils.getInputFlashMap(request);
  if (inputFlashMap != null) {
    String some = (String) inputFlashMap.get("some");
    // do the job
  }
}

附:您可以在 handlePost 中返回 return new ModelAndView("redirect:/foo/bar");。

编辑:

JavaDoc 说:

A RedirectAttributes model is empty when the method is called and is never used unless the method returns a redirect view name or a RedirectView.

它没有提到ModelAndView，所以也许改变handlePost返回"redirect:/foo/bar"字符串或RedirectView:

@RequestMapping(value = "/bar", method = RequestMethod.POST)
public RedirectView handlePost(RedirectAttributes redirectAttrs) {
  redirectAttrs.addFlashAttributes("some", "thing");
  return new RedirectView("/foo/bar", true);
}

我在我的代码中使用 RedirectAttributes 和 RedirectView 和 model.asMap() 方法，它工作正常。