ModelAttribute注解使用与spring重定向传参 

@ModelAttribute可以用于修饰controller里的方法和参数，将被修饰的对象的值绑定到指定名称的属性里。
当修饰方法时，方法返回的值会在该controller里每个访问处理前绑定一次。
修饰参数时，如果想重定向或者转发到另一个方法后，还能在另一个方法中取得model里的参数值，可以使用两种方法（假设方法A里跳到方法B，要取得方法A里的参数）：

1.将方法A里的参数放在RedirectAttributes里，使用重定向进到B方法，在方法B里获取参数。

2.使用forward转发到B，使用HttpServletRequest.getAttribute()方法获取参数。

测试代码：

 1 @Controller
 2 @RequestMapping("/")
 3 public class ModelTest {
 4     @Value("wj")
 5     private String userName;
 6 
 7     @ModelAttribute("sayHello")
 8     public String runBeforeEachHandlerCalled() {
 9         System.out.println("runBeforeEachHandlerCalled方法执行");
10         String sayHello = "Hello " + userName;
11         return sayHello;
12     }
13 
14     @RequestMapping(value = "/home",method = RequestMethod.GET)
15     public String toHomePage() {
16        return "index";
17     }
18 
19     @RequestMapping(value = "/handler1")
20     public String redirectMethod(@ModelAttribute("key2")String key2, RedirectAttributes attrbs) {
21         System.out.println("handler1里");
22 
23         key2 = "key2value";
24 
25         attrbs.addAttribute("redirectAttr1","redirectAttr1value");
26         attrbs.addFlashAttribute("redirectAttr2","redirectAttr2value");
27 
28 //       return "forward:/handler2";
29 //       return new RedirectView("handler2");
30         return "redirect:handler2";
31     }
32 
33     @RequestMapping(value = "/handler2")
34     public String redirectDestination(ModelMap map, String redirectAttr1,
35                                       @ModelAttribute("redirectAttr2")String redirectAttr2,
36                                       HttpServletRequest request, RedirectAttributes attrbs) {
37         System.out.println("handler2里");
38         System.out.println("ModelMap.key2值为：" + map.get("key2"));
39         System.out.println("redirect.request.key2:" + request.getAttribute("key2"));
40         System.out.println("redirect.request.redirectAttr1:" + request.getAttribute("redirectAttr1"));
41         System.out.println("redirectAttr1值为：" + redirectAttr1);
42         System.out.println("redirectAttr2值为：" + redirectAttr2);
43         map.put("key3","key3value");
44         attrbs.addAttribute("key4","key4value");
45         return "forward:handler3";
46     }
47 
48     @RequestMapping(value = "/handler3")
49     public String forwardDestination(ModelMap map,@ModelAttribute("redirectAttr1") String redirectAttr1,
50                                      @ModelAttribute("redirectAttr2")String redirectAttr2,@ModelAttribute("key4")String key4,
51                                       HttpServletRequest request) {
52         System.out.println("handler3里");
53         System.out.println("ModelMap.key3值为：" + map.get("key3"));
54         System.out.println("forward.request.key3:" + request.getAttribute("key3"));
55         System.out.println("forward.request.redirectAttr1:" + request.getAttribute("redirectAttr1"));
56         System.out.println("redirectAttr1值为：" + redirectAttr1);
57         System.out.println("redirectAttr2值为：" + redirectAttr2);
58         System.out.println("key4值为：" + key4);
59         return "index";
60     }
61 
62 }
View Code

index.jsp：

<%@ page language="java" contentType="text/html; charset=utf-8"
         pageEncoding="utf-8"%>
<html>
<body>
<h2>${sayHello}</h2>
</body>
</html>
View Code

输出：

runBeforeEachHandlerCalled方法执行
handler1里
runBeforeEachHandlerCalled方法执行
handler2里
ModelMap.key2值为：null
redirect.request.key2:null
redirect.request.redirectAttr1:null
redirectAttr1值为：redirectAttr1value
redirectAttr2值为：redirectAttr2value
runBeforeEachHandlerCalled方法执行
handler3里
ModelMap.key3值为：null
forward.request.key3:key3value
forward.request.redirectAttr1:null
redirectAttr1值为：redirectAttr1value
redirectAttr2值为：redirectAttr2value
key4值为：
View Code

 




posted @ 2018-01-14 14:09  JillWen  阅读(1159)  评论(0)  编辑  收藏  举报