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

The @Controller annotation in Spring is used to designate a class as an MVC controller that handles HTTP requests and returns the name of a view, such as a JSP or Thymeleaf template.

@RestController is a specialized annotation that combines @Controller and @ResponseBody. It indicates that the controller methods return data directly in the HTTP response body, usually in JSON or XML format, without using views.

Example:

@RestController
public class ApiController {
    @GetMapping("/api/data")
    public Data getData() {
        return new Data("value"); // will be automatically serialized to JSON
    }
}

@Controller
public class WebController {
    @GetMapping("/page")
    public String getPage(Model model) {
        model.addAttribute("attr", "value");
        return "pageView"; // name of the template for rendering
    }
}

Thus, @RestController is convenient for creating REST APIs, while @Controller is used for web applications with server-side HTML generation.