Spring MVC中redirect到一个页面，同时带些信息过去进行显示，但是不通过Session方式及URL方式

如何在Spring MVC中redirect到一个页面，同时带些信息过去进行显示，但是不通过Session方式及URL方式？ 

想用跟正常的ModelAndView方式，但是用了RedirectView过去是拿不到的 ，如： 

 new ModelAndView(new RedirectView("xxx.do"),"modelName",modelMap);

只能用Session这种方式 

 request.getSession().setAttribute("msg",map);

或URL后面加信息 

 new ModelAndView(new RedirectView("xxx.do?msg=xyz");

然后在页面获取进行显示？ 

有没有更好的方法？

in your controller: 

 new ModelAndView(new RedirectView("xxx.do"),"modelName",modelMap);

then DispatcherServlet render the view with your modelMap: 

 DispatcherServlet.render(ModelAndView mv, HttpServletRequest request, HttpServletResponse response){
 ...
 //call view's render method
 view.render(mv.getModelInternal(), request, response);
 }
 ...

 AbstractView.render(Map model, HttpServletRequest request, HttpServletResponse response){
 ...
 //the model still here...
 renderMergedOutputModel(mergedModel, request, response);
 }

 RedirectView.renderMergedOutputModel(Map model, HttpServletRequest request, HttpServletResponse response){
 ...
 //Append query properties to the redirect URL. Here, the modelMap represented by url...
 appendQueryProperties(targetUrl, model, this.encodingScheme);

 //do redirect
 sendRedirect(request, response, targetUrl.toString(), this.http10Compatible);
 }

没有测试过, 看了下spring mvc的source code. 
从上面的代码来看, 

 new ModelAndView(new RedirectView("xxx.do"),"modelName",modelMap);

是可以的... 

你应该Debug一下, 看看model在什么地方丢了...

做了个测试, 证明我上面的判断是正确的... 
而且也说明了,为什么你的方法拿不到正确的值 

 package com.simba.test;

 import java.util.HashMap;
 import java.util.Map;

 import junit.framework.TestCase;

 import org.springframework.mock.web.MockHttpServletRequest;
 import org.springframework.mock.web.MockHttpServletResponse;
 import org.springframework.web.servlet.ModelAndView;
 import org.springframework.web.servlet.view.RedirectView;

 public class TestRedirectView extends TestCase{

     protected MockHttpServletRequest request = new MockHttpServletRequest("GET", "");
     protected MockHttpServletResponse response = new MockHttpServletResponse();

     public void testRedirect() throws Exception{
         Map<String, String> map = new HashMap<String, String>();
         map.put("key1", "value1");
         map.put("key2", "value2");

         //这种用法,map就是ModelAndView中的Model.
         ModelAndView mv = new ModelAndView(new RedirectView("/foo/bar.jsp"), map);

         //这里用getModel()与DispatcherServlet中用getModelInternal是一样的.
         mv.getView().render(mv.getModel(), request, response);

         assertEquals(response.getRedirectedUrl(),"/foo/bar.jsp?key1=value1&key2=value2");
     }

     public void testWrongRedirect() throws Exception{
         Map<String, String> map = new HashMap<String, String>();
         map.put("key1", "value1");
         map.put("key2", "value2");

         //这种用法,map就是ModelAndView中Model的一个key/value对了...
         ModelAndView mv = new ModelAndView(new RedirectView("/foo/bar.jsp"), "model", map);

         //这里用getModel()与DispatcherServlet中用getModelInternal是一样的.
         mv.getView().render(mv.getModel(), request, response);

         assertTrue(response.getRedirectedUrl().contains("/foo/bar.jsp?model="));
     }
 }

也就是无论用有modelName或无modelName的方式传递给ModelAndView，这些值是有都转化为URL进行表示了，只不过在页面上面无法通过通常的方式取得，如我用的JSTL 1.0.6标签： 

 <c:out value='${modelName}'/>
 <c:out value='${modelName.keyxxx}'/>

或 

 <c:out value='${keyxxx}'/>

post and redirect 
想要在两个请求之间传递信息，除了session, url transfer之外，还有很多手段啊： 
cookie 
cache 
database 
file 
... 
就靠你权衡了