@RestController

// @Controller (기존) — com.smhrd.controller
@Controller
public class BoardController {
    @GetMapping("/board/{num}")
    public String view(@PathVariable int num, Model model) {
        model.addAttribute("board", service.selectOne(num));
        return "board/view";    // ← JSP ViewName
    }
}

// @RestController (REST) — com.smhrd.controller
@RestController
public class BoardApiController {
    @GetMapping("/api/boards/{num}")
    public Board view(@PathVariable int num) {
        return service.selectOne(num);   // ← 그대로 JSON 응답
    }
}

Run on Server 또는 javac+java 로 실행하고 결과를 확인합니다.