What are the differences between Model, ModelMap, and ModelAndView?

Question

What are the main differences between the following Spring Framework classes?

• Model
• ModelMap
• ModelAndView

Using Model.put(String,Object) we can access the values in .jsp files, but ModelMap.addAttribute(String,Object) also did same thing. I do not understand the difference between these classes.

Answer 1

Model is an interface while ModelMap is a class.

ModelAndView is just a container for both a ModelMap and a view object. It allows a controller to return both as a single value.

Answer 2

Differences between Model, ModelMap, and ModelAndView

Model: It is an Interface. It defines a holder for model attributes and primarily designed for adding attributes to the model.

Example:

@RequestMapping(method = RequestMethod.GET)     public String printHello(Model model) {           model.addAttribute("message", "Hello World!!");           return "hello";        } 

ModelMap: Implementation of Map for use when building model data for use with UI tools.Supports chained calls and generation of model attribute names.

Example:

@RequestMapping("/helloworld") public String hello(ModelMap map) {     String helloWorldMessage = "Hello world!";     String welcomeMessage = "Welcome!";     map.addAttribute("helloMessage", helloWorldMessage);     map.addAttribute("welcomeMessage", welcomeMessage);     return "hello"; } 

ModelAndView: This class merely holds both to make it possible for a controller to return both model and view in a single return value.

Example:

@RequestMapping("/welcome") public ModelAndView helloWorld() {         String message = "Hello World!";         return new ModelAndView("welcome", "message", message);     }