문제 1 - 두 수를 연산해 주는 계산기 만들기

DTO

@Getter
@Setter
public class CalculatorRequest {
    private int add;
    private int minus;
    private int multiply;
}

Controller

@GetMapping("/api/v1/calc")
public CalculatorRequest calculator(
		@RequestParam int num1, 
		@RequestParam int num2
) {
    CalculatorRequest request = new CalculatorRequest();

    request.setAdd(num1 + num2);
    request.setMinus(num1 - num2);
    request.setMultiply(num1 * num2);

    return request;
}

Result

문제 2 - 날짜를 입력하면 요일을 알려주는 API 만들기

DTO

@Getter
@Setter
public class DayOfWeekRequest {
    private String dayOfTheWeek;
}

Controller

@GetMapping("api/v1/day-of-the-week")
public DayOfWeekRequest dateToDayOfWeek(@RequestParam String date) {
    // String to LocalDate
    LocalDate localDate = LocalDate.parse(date, DateTimeFormatter.ISO_DATE);

    //DayOfWeekRequest 객체 생성
    DayOfWeekRequest request = new DayOfWeekRequest();

    // LocalDate에서 요일 추출
    DayOfWeek dayOfWeek = localDate.getDayOfWeek();

    // "MON"과 같은 표기 설정
    request.setDayOfTheWeek(
            dayOfWeek.getDisplayName(TextStyle.SHORT, Locale.US).toUpperCase()
    );
    return request;
}

Result