SpringMVC传值与取值

一、传值:

第一种:ModelAndvie

//1.modelAndView
@RequestMapping({"/index"})
public ModelAndView index(){
    //查询数据,获取所有的用户信息
    List userItems = UserData.userItems;
    ModelAndView  mav=new ModelAndView();//ModelAndView存值的情况下方法的返回值必须是ModelAndView
    
    //设置数据(模型)
    mav.addObject("userItems",userItems);
    //设置视图名称
    mav.setViewName("index");
    return mav;
}

第二种、Model

//2.model
@RequestMapping("/index")
public String index(Model model){
    List<User> userItems = UserData.userItems;
    model.addAttribute("userItems",userItems);
    return "index";
}

第三种、ModelMap modelMap

@RequestMapping("index")
public String index(ModelMap modelMap){
    List<User> userItems = UserData.userItems;
    modelMap.addAttribute("userItems",userItems);
    return "index";
}

第四种、Map

 //4.Map
@RequestMapping("index")
 public String index(Map map){
     List userItems = UserData.userItems;
     map.put("userItems",userItems);
     map.put("a","xiaoxiong");
     return "index";
 } 

第五种、request

 @RequestMapping("/test")
    public String testRequestByServletAPI(HttpServletRequest request) {
   User user= new User();
        //想request作用域中共享数据（存数据）
        request.setAttribute("user", "user");

        return "succeed";//request作用域中存数据转发到相应的页面进行取值
    }

二、取值

1、对象取值

@RequestMapping("/testpojo")

    public  String  testpojo(User user){
        //根据实体类获取表单提交的参数
        System.out.println(user);
        return "testpojo";
    }

2、注解取值

@RequestMapping("/add")
//RequestParam 的三个参数 value表示name的字段名称required参数是否是必须的
public String add(Integer id,
                  @RequestParam(value = "userName",required = true,defaultValue = "小熊") String Name,
                  @RequestParam(value = "age",required = true,defaultValue = "22") Integer age,
                  @RequestParam(value = "email",required = true,defaultValue = "[email protected]") String email,
                  @RequestParam(value = "address",required = true,defaultValue = "湖南长沙") String address){
    User user =new User(id,Name,age,email,address);
    UserData.userItems.add(user);
    //重定向到index进行所有的查询
    return "redirect:/index";
}

3、request

@RequestMapping("/servltecontrollerapl")
       //方法中定义形参
    public String ServletControllerApl(HttpServletRequest request) {
        //根据页面传入的参数后台进行取值(前端页面传入的参数都全部后端进行取值)
        String username = request.getParameter("username");
        String pas = request.getParameter("password");

        System.out.println(username+"\t"+pas);
        return "test";//跳转到参数渲染的页面
    }