Spring MVC中页面向后台传值的几种方式

在学习 Spring Mvc 过程中，有必要来先了解几个关键参数：
   @Controller：
         在类上注解，则此类将编程一个控制器，在项目启动 Spring 将自动扫描此类，并进行对应URL路由映射。
@Controller
public class UserAction
{
    
}
　 @RequestMapping
         指定URL映射路径，如果在控制器上配置 RequestMapping  ，具体请求方法也配置路径则映射的路径为两者路径的叠加 常用映射如:RequestMapping("url.html")
        配置映射路径：

@Controller
public class UserAction
{
    @RequestMapping(value = "/get_alluser.html")
   public ModelAndView GetAllUser(String Id)
   {
   }
}

以上配置映射
 　　  http://***:8080:web1/get_alluser.html：
         如在 @Controller添加 @RequestMapping(value = "/user"),则映射路径变成
          http://***:8080:web1/user/get_alluser.html
   @ResponseBody
      将注解方法对应的字符串直接返回
   @RequestParam
      自动映射URL对应的参数到Action上面的数值，RequestParam 默认为必填参数。
    
   @PathVariable
      获取@RequestMapping 配置指定格式的URL映射参数

/*
      *   直接输出 HTML，或JSON 字符串
      *   请求路径:
      *       /web1/urlinfo/getcontent.html?key=rhythmk
      *      /web1/urlinfo/getcontent.json?key=rhythmk
      * */
    @ResponseBody
    @RequestMapping(value = "/getcontent.**")
    public String GetContent(
            @RequestParam("key") String key,
            @RequestParam(value = "key2", required = false, defaultValue = "defaultValue") String key2) {
        System.out.println("getcontent 被调用");
        String result = "直接返回内容  - key:" + key + ",key2:" + key2;
        System.out.println(result);
        return result;
    }

/*
     * RequestMapping 支持 Ant 风格的URL配置 ：
     *  请求路径：
     *     /urlinfo/geturlant/config.html?key=adddd
     */
    @ResponseBody
    @RequestMapping(value = "/geturlant/**.html")
    public String getUrlAnt(HttpServletRequest request) {
        String result = "?后面的参数为：" + request.getQueryString();
        return result;
    }

/*
     * 配置指定格式的URL，映射到对应的参数
     *   请求路径：/web1/urlinfo/geturlparam/12_123.html
     *    
     * */
   
    @RequestMapping(value = "/geturlparam/{id}_{menuId}.html")
    public ModelAndView getUrlParam(@PathVariable("id") String id,
            @PathVariable("menuId") String menuId) {
        ModelAndView mode = new ModelAndView(ShowMsg);
        mode.addObject("msg", "获取到的Id:" + id + ",menuId:" + menuId);
        return mode;
    }

/*
     * 只接收Post 请求
     */
    @ResponseBody
    @RequestMapping(value = "/posturl.html", method = RequestMethod.POST)
    public String UrlMethod(@RequestParam String id) {
        return "只能是Post请求,获取到的Id:" + id;
    }

/*
     *   写入 cookie
     * */
    @RequestMapping("/writecookies.html")
    public ModelAndView writeCookies(@RequestParam String value,
            HttpServletResponse response) {

response.addCookie(new Cookie("key", value));
        ModelAndView mode = new ModelAndView(ShowMsg);
        mode.addObject("msg", "cookies 写入成功");
        return  mode ;
    }

/*
       *  通过 @CookieValue 获取对应的key的值
       * */
    @RequestMapping("/getcookies.html")
    public ModelAndView getCookie(@CookieValue("key") String cookvalue) {
        ModelAndView mode = new ModelAndView(ShowMsg);
        mode.addObject("msg", "cookies=" + cookvalue);
        return mode;
    }

/*
     * 将 Servlet Api 作为参数传入
     *   可以在action中直接使用  HttpServletResponse，HttpServletRequest
     * */
    @RequestMapping("/servlet.html")
    public String Servlet1(HttpServletResponse response,
            HttpServletRequest request) {

Boolean result = (request != null && response != null);
        ModelAndView mode = new ModelAndView();
        mode.addObject("msg", "result=" + result.toString());
        return ShowMsg;

}

/*
     *   根据URL传入的参数实例化对象
     *  
     *   如： http://127.0.0.1:8080/web1/urlinfo/getobject.html?UserId=1&UserName=ad
     * */
    @RequestMapping("getobject.html")
    public ModelAndView getObject(UserInfo user) {
        String result = "用户ID：" + user.getUserId().toString() + ",用户名:"
                + user.getUserName().toString();
        ModelAndView mode = new ModelAndView(ShowMsg);
        mode.addObject("msg", "result=" + result.toString());
        return mode;
    }

实现页面跳转：

/*
     * 实现页面跳转
     * /web1/urlinfo/redirectpage.html
     * */
    @RequestMapping("/redirectpage.html")
    public String RedirectPage()
    {
        return  "redirect:getcookies.html?r=10";
               
    }

直接回传JSON
    请求的URL地址一定是以.json结尾，否则异常
     Failed to load resource: the server responded with a status of 406 (Not Acceptable) ： The resource identified by this request is only capable of generating responses with characteristics not acceptable according to the request "accept" headers () 
回传实体：

@JsonSerialize(include = JsonSerialize.Inclusion.NON_NULL)
public class UserInfo {

private  Integer UserId;
      public Integer getUserId() {
        return UserId;
    }
    public void setUserId(Integer userId) {
        UserId = userId;
    }
    public String getUserName() {
        return UserName;
    }
    public void setUserName(String userName) {
        UserName = userName;
    }
    private String UserName;
     
    
}

回传 action

@ResponseBody
    @RequestMapping("/getuser.json")
    public UserInfo  GetUser()
    {
        System.out.println("getuser");
        UserInfo model=new  UserInfo();
        model.setUserId(100);
        model.setUserName("王坤");
        return model;
    }

请求：
/web1/urlinfo/getuser.json
输出：
{"userId":100,"userName":"王坤"}