springMVC RedirectAttributes

@Controller
public class TestController {

    @RequestMapping("/redirectDemo")
    public String redirectDemo(RedirectAttributes attributes){
      attributes.addFlashAttribute("message","error.user.login");
      return "redirect:/index";
    }
    @RequestMapping("/index")
    public String index(){
        return "index";
    }

}

 index.ftl

 ${message}

@RequestMapping("/redirect")
    public String redirectTest(RedirectAttributes attr){
        attr.addAttribute("userName", "root");
        attr.addFlashAttribute("password","123456");
        return "redirect:/book/getbook";
    }

@RequestMapping("/getbook")
    @ResponseBody
    public String getBook(ModelMap map,HttpServletRequest request,@RequestParam("userName") String userName,
            @RequestParam(value = "password",required = false) String password){
        System.out.println("userName : "+map.get("userName"));
        System.out.println("userName1 :" + request.getAttribute("userName"));
        System.out.println("userName2 :" + request.getParameter("userName"));
        System.out.println("userName3 : " + userName);
        
        
        System.out.println("password : "+map.get("password"));
        System.out.println("password1 :" + request.getAttribute("password"));
        System.out.println("password2 :" + request.getParameter("password"));
        System.out.println("password3 : " + password);
        
        return "result";
    }

请求结果

 

url ： http://localhost:9019/book/getbook?userName=root

 

控制台输出

userName : null
userName1 :null
userName2 :root
userName3 : root
password : 123456
password1 :null
password2 :null
password3 : null

总结：

 

请求转发需要携带参数时

1、使用  RedirectAttributes 的 addAttribute（）方法设置参数，则参数将直接拼接在转发url后面，然后可以在通过request.getParameter("userName")) 和 直接通过spring mvc配置参数映射接收到参数

2、使用 RedirectAttributes  的 addFlashAttribute（）方法设置参数，则参数不会出现在转发url中，然后可以通过modelMap 取出参数

 

 

补充：

请求结果页面代码

result welcome in $!{title}; ${userName}; ${password}