[인프런 워밍업 클럽]BE 두번째 과제 - api 개발

목표

추가적인 GET, POST api를 만들어 보며 API 개발에 익숙해지기

문제1

두 수를 입력하면, 다음과 같은 결과가 나오는 GET API를 만들어 보자!

• path : /api/v1/calc

• 쿼리 파라미터 : num1, num2

{
  "add": 덧셈결과,
  "minus": 뺄셈결과,
  "multiply": 곱셈결과
}

package com.group.libraryapp.controller;

import com.group.libraryapp.domain.Calculator;
import com.group.libraryapp.dto.calculator.response.CalculatorResponse;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class CalculatorController {

	@GetMapping("/api/v1/calc")
    public Calculator calculateTwoNumber(CalculatorResponse response) {
        int add = response.getNum1() + response.getNum2();
        int minus = response.getNum1() - response.getNum2();
        int multiply = response.getNum1() * response.getNum2();
        return new Calculator(add, minus, multiply);
    }
}

package com.group.libraryapp.domain;

public class Calculator {
    private int add;
    private int minus;
    private int multiply;

    public Calculator(int add, int minus, int multiply) {
        this.add = add;
        this.minus = minus;
        this.multiply = multiply;
    }

    public int getAdd() {
        return add;
    }

    public int getMinus() {
        return minus;
    }

    public int getMultiply() {
        return multiply;
    }
}

package com.group.libraryapp.dto.calculator.response;

public class CalculatorResponse {
    private int num1;
    private int num2;

    public CalculatorResponse(int num1, int num2) {
        this.num1 = num1;
        this.num2 = num2;
    }

    public int getNum1() {
        return num1;
    }

    public int getNum2() {
        return num2;
    }
}

문제2

날짜를 입력하면, 몇 요일인지 알려주는 GET API를 만들어 보자!
path와 쿼리 파라미터는 임의로 만들어도 상관없다.

예시

GET /api/v1/day-of-week?date=2023-01-01

    {
       "dayOfTheWeek": "SUN"  
    }  

package com.group.libraryapp.controller;

import com.group.libraryapp.domain.Day;
import com.group.libraryapp.dto.day.request.DayOfTheWeekRequest;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import java.time.LocalDate;

@RestController
public class DayOfTheWeekController {

    @GetMapping("/api/v1/day-of-the-week")
    public Day getDay(DayOfTheWeekRequest request) {
        LocalDate date = LocalDate.parse(request.getDate());
        return new Day(date.getDayOfWeek());
    }
}

package com.group.libraryapp.dto.day.request;

public class DayOfTheWeekRequest {
    private String date;

    public DayOfTheWeekRequest(String date) {
        this.date = date;
    }

    public String getDate() {
        return date;
    }
}

package com.group.libraryapp.domain;

import java.time.DayOfWeek;

public class Day {
    private DayOfWeek dayOfTheWeek;

    public Day(DayOfWeek dayOfTheWeek) {
        this.dayOfTheWeek = dayOfTheWeek;
    }

    // 왜 getter가 있어야 되지??
    public DayOfWeek getDayOfTheWeek() {
        return dayOfTheWeek;
    }
}

문제3

여러 수를 받아 총 합을 반환하는 POST API를 만들어 보자!
API에서 받는 Body는 다음과 같은 형태이다. (HINT : 요청을 받는 DTO에서 List를 갖고 있으면 JSON의 배열을 받을 수 있습니다.)

{
  "numbers": [1,2,3,4,5]
}

반환 결과

15

package com.group.libraryapp.controller;

import com.group.libraryapp.dto.calculator.request.CalculatorAddManyRequest;

import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

@RestController
public class CalculatorController {
@PostMapping("/addMany")
    public int addManyNumber(@RequestBody CalculatorAddManyRequest request) {
        int sum = 0;

        List<Integer> numbers = request.getNumbers();

        for (int number : numbers) {
            sum += number;
        }

        return sum;
    }
}

package com.group.libraryapp.dto.calculator.request;

import java.util.List;

public class CalculatorAddManyRequest {
    List<Integer> numbers;

    // 왜 기본 생성자를 생성해줘야 하지?
    public CalculatorAddManyRequest() {
    }

    public CalculatorAddManyRequest(List<Integer> numbers) {
        this.numbers = numbers;
    }

    public List<Integer> getNumbers() {
        return numbers;
    }
}

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참고

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