MVC method Return Type

　　ModelAndView Return Value Type:

　　　　1. When the return is null, the page does not jump.

　　　　2. When the return value is not specified view name, view name as the default name to request a jump.

　　　　3. When the return value specifies the name of the view, the program will jump by view name.

/*添加*/
@RequestMapping("/getSale")
public ModelAndView addSale(Sale sale,HttpServletRequest request,ModelAndView mv){
    if (sale!=null) {
        Double totalPrice = sale.getPrice() * sale.getQuantity();
        sale.setTotalPrice(totalPrice);
        sale.setSaleDate(new Date());
        Users user = (Users) request.getSession().getAttribute("user");
        sale.setUserId(user.getUid());
        int i = userService.addSale(sale);
        if (i > 0) {
            mv.setViewName("saleList");
        } else {
            mv.setViewName("prodectAdd");
        }
    }
    return mv;
}

　　Objectl return type;

/*绑定下拉框*/
@RequestMapping("/prodectName")
@ResponseBody
public Object getprodectName(){
    List<Product> products = userService.getproductName();
    return products;
}

　　String Return Value Type:

　　　　1, if the return value is null, then a jump to request the name of the view name

　　　　2, if the return value is specified, then a jump according to the specified view name as the return value, may carry data model, modeMap.

　　　　3, if the return value with a forward or redirect prefix, or the corresponding request will be redirected, but can not carry data mvc data model, the data may be carried by ServletApi.

@RequestMapping ( " / available for purchase " )
 public String available for purchase (String the userName, the Model Model) {
     // save the user name corresponding to the scope 
    model.addAttribute ( " the userName " , the userName);
     return  " available for purchase " ; 
}

MVC parameter passing

　　Request parameter automatic conversion

　　　　JSP page

form class="loginForm" action="/user/getUser" method="post" >
    <div class="inputbox"  style="text-align:center; ">
        <label for="user">用户名：</label>
        <input id="user" type="text" name="userName"Please enter your user name"= placeholder" />
    </div>
    <div class="password"  style="text-align:center; " >
        <label for="mima">密码：</label>
        <input id="mima" type="password" name="password" placeholder="请输入密码" />
    </div>
    <div class="subBtn"  style="text-align:center; ">
        <input type="submit" value="登录" />
        <input type="reset" value="重置"/>
    </div>
</form>

　　　　Point * Note: Method Parameter Name in the Controller must be consistent with the value of the name attribute of the form element

/*登录*/
@RequestMapping("/getUser")
@ResponseBody
private ModelAndView getUser(String userName, String password, ModelAndView mv, HttpServletRequest request, HttpServletResponse response, HttpSession session){
    Users user = userService.getUser(userName,password);
    System.out.println("user======"+user);
    if (user!=null){
        System.out.println("成功");
        //登录成功
      request.getSession().setAttribute("user",user);
        //转发
        mv.setViewName("index");
    }else{
        //登录失败
        mv.setViewName("login");
    }
    return mv;
}

　　Assembly of the object request parameters POJO

　　　　New Person　　

public class Person {
    private String username;
    private int age;
    //省略get/set方法
}

　　　　Controller

// When the entity name attribute class attribute names and forms of the same element, to complete the automatic assembly 
@RequestMapping (value = " personObject " , Method = RequestMethod.POST)
 public String personObject (the Person Person) { 
    the System. OUT .println (Person);
     return  " Hello " ; 
}

MVC i.e., the return value parameter