What is the difference between @Controller and @RestController in Spring Framework?

@Controller is used to mark a class as a controller component in the Spring MVC architecture. It is often used for handling web requests and returning ModelAndView or view names.

@RestController is a specialized version of @Controller. It combines @Controller and @ResponseBody, indicating that the return values of methods should be automatically converted into a format suitable for HTTP responses (e.g., JSON or XML). It is most commonly used for creating RESTful web services.

Main differences:

• @Controller: Returns ModelAndView or a view name, which is then processed by a view resolver.
• @RestController: Returns data directly (by default in JSON/XML), which is sent back to the client. No need for @ResponseBody on each method.

Example:

// Using @Controller
@Controller
public class ViewController {

    @GetMapping("/view")
    public String showView() {
        return "myview"; // Returns the view name
    }
}

// Using @RestController
@RestController
public class RestDataController {

    @GetMapping("/data")
    public MyData getData() {
        return new MyData("Hello", "World"); // Returns data that is converted to JSON
    }

    static class MyData {
        private String field1;
        private String field2;

        public MyData(String field1, String field2) {
            this.field1 = field1;
            this.field2 = field2;
        }

        public String getField1() { return field1; }
        public String getField2() { return field2; }
    }
}