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Explain ModelAndView with examples

Explain ModelAndView

MAV is a class in Spring MVC that represents both the model (data) and the view (UI) in a single object. It is used to pass data from a controller to a view and to specify which view should be rendered.

Purpose:

It simplifies the process of returning data and specifying the view from within a controller method.

Key Components:

1. Model: Holds the data that needs to be displayed on the view. It is represented by a map of attributes.

2. View: The logical view name that will be resolved by a view resolver to display the data.

ModelAndView

Controller with `ModelAndView`
UserController.java
```java
import org.springframework.stereotype.Controller;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
	
@Controller
public class UserController {

    @RequestMapping(value = "/user", method = RequestMethod.GET)
    public ModelAndView getUser() {
        // Create a new ModelAnd View object
        ModelAnd View modelAnd View = new ModelAnd View();

        // Add data to the model
        modelAnd View.addObject("name", "John Doe");
        modelAnd View.addObject("email", "john.doe@example.com");

        // Specify the view name
        modelAndView.setViewName("userView");

        return modelAndView;
    }
}
```

In this example:

  • Model: The ModelAnd View object holds data (name and email) that will be passed to the view.
  • View: The setViewName("userView") method specifies that the userView view should be used to render the data.

View (JSP)

Example
userView.jsp
```jsp
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<html>
<head>
    <title>User Information</title>
</head>
<body>
    <h2>User Details</h2>
    <p>Name: ${name}</p>
    <p>Email: ${email}</p>
</body>
</html>
```

In this example:

  • ${name} and ${email}: These expressions access the model attributes that were set in the controller.

Summary

  • ModelAnd View: Combines both the model data and the view information into a single object.
  • Components:
  • Model: Contains data to be displayed.
  • View: The name of the view to be rendered.

  1. Usage:
    • Create an instance of ModelAnd View.
    • Add attributes to the model.
    • Set the view name.
    • Return the ModelAnd View object from the controller method.

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