[Android/Kotlin] retrofit2 정리

오늘 예제는 http와 통신하는 방법인 retrofit에 대해 정리해보았다.

 

1. gradle 추가

implementation "com.squareup.retrofit2:retrofit:2.9.0"
implementation "com.squareup.retrofit2:converter-gson:2.9.0"

 

2. api service

api 구현은 박스오피스 영화 순위를 예로 들겠다.

interface RetrofitInterface {
    @GET("http://kobis.or.kr/kobisopenapi/webservice/rest/boxoffice/searchDailyBoxOfficeList.json")
    fun getBoxOffice(
        @Query("key") key: String?,
        @Query("targetDt") targetDt: String?,
    ): Call<Result?>?
}

함수 위에 GET, POST, DELETE, PUT, HEAD 중 알맞는 기능을 쓰고 안에 url을 작성한다.

 

3. api call response 클래스 작성

받아올 데이터들을 선정해 data class를 만든다.

data class BoxOfficeResult (
    @SerializedName("boxofficeType")
    @Expose
    var boxofficeType: String,

    @SerializedName("showRange")
    @Expose
    var showRange: String,

    @SerializedName("dailyBoxOfficeList")
    @Expose
    var dailyBoxOfficeList: List<DailyBoxOfficeList>? = null
)

• @SerializedName: JSON으로 serialize 될 때 매칭되는 이름을 명시하는 목적으로 사용한다.
• @Expose : object 중 해당 값이 null일 경우, json으로 만들 필드를 자동 생략

 

4. retrofit builder

class RetrofitClient {
    private var instance: RetrofitClient? = null
    private var retrofitInterface: RetrofitInterface
    private var baseUrl: String = "http://www.kobis.or.kr"

    init {
        val retrofit = Retrofit.Builder()
            .baseUrl(baseUrl)
            .addConverterFactory(GsonConverterFactory.create())
            .build()
        retrofitInterface = retrofit.create(RetrofitInterface::class.java)
    }

    fun getInstance(): RetrofitClient? {
        if (instance == null) {
            instance = RetrofitClient()
        }
        return instance
    }

    fun getRetrofitInterface(): RetrofitInterface {
        return retrofitInterface
    }
}

 

 

5. 구현

package com.example.retrofitapplication

import android.os.Bundle
import android.util.Log
import androidx.appcompat.app.AppCompatActivity
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import com.example.retrofitapplication.class1.RetrofitClient
import com.example.retrofitapplication.class1.RetrofitInterface
import com.example.retrofitapplication.class1.data.BoxOfficeResult
import com.example.retrofitapplication.class1.recyclerview.MovieAdapter
import retrofit2.Call
import retrofit2.Response
import java.text.SimpleDateFormat
import java.util.*
import retrofit2.Callback
import com.example.retrofitapplication.class1.data.Result


class MainActivity : AppCompatActivity() {

    private lateinit var recyclerView: RecyclerView
    private lateinit var mAdapter: MovieAdapter

    private lateinit var retrofitClient: RetrofitClient
    private lateinit var retrofitInterface: RetrofitInterface

    private val API_KEY: String = "32959eb64a93e024aaf4bb540b00e85c"    // Api 키
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        recyclerView = findViewById(R.id.recyclerView)
        recyclerView.layoutManager = LinearLayoutManager(applicationContext, LinearLayoutManager.VERTICAL, false)

        // 초기화
        retrofitClient = RetrofitClient().getInstance()!!
        retrofitInterface = RetrofitClient().getRetrofitInterface()

        // 하루 전 날짜 구하기
        val day: Calendar = Calendar.getInstance()
        day.add(Calendar.DATE, -1)
        val time: String =SimpleDateFormat("yyyyMMdd").format(day.time).toString()

        retrofitInterface.getBoxOffice(API_KEY, time)!!.enqueue(object : Callback<Result?> {

            override fun onResponse(call: Call<Result?>, response: Response<Result?>) {
                val result: Result? = response.body()
                Log.d("retrofit", "onResponse result: $result")
                val boxOfficeResult: BoxOfficeResult = result!!.boxOfficeResult
                Log.d("retrofit", "Data fetch success")
                mAdapter = MovieAdapter(boxOfficeResult.dailyBoxOfficeList!!)
                recyclerView.adapter = mAdapter
            }

            override fun onFailure(call: Call<Result?>?, t: Throwable) {
                Log.d("retrofit", t.message!!)
            }
        })

    }

 

---

retrofit은 개발할때 자주 쓰이기 때문에 꼭 알아두는 것이 좋다.