API 불러오기 HttpURLConnection, Gson, Rtrofit2 까지 모두

API 불러오는 연습을 하고있다.

라이브러리를 하나도 사용하지 않는 HttpURLConnection ->  Gson 라이브러리 사용 -> Rtrofit2까지 바꿔보면서 진행했다. Retrofit2는 Api 불러올 때 많이 사용해봤어서 익숙했지만 HttpURLConnection은 처음 사용해보았다.

 

1.  HttpURLConnection

HttpURLConnection 을 사용해 보았고, 아래 공식문서를 참고하여 작성해 보았다.

HttpURLConnection  |  Android Developers

 

setRequestProperty("User-Agent", "Mozilla/5.0") 이 부분 때문에 시간을 많이 썼다. 저 부분을 작성하지 않았더니 403에러가 자꾸 떴다. 내 API 키가 잘못된건가 싶어서 재발급도 받았지만 똑같은 오류가 계속 나타났다. 그때부터 구글링을 하기 시작했고, Stack Overflow에서 발견하여 문제를 해결할 수 있었다. 

 

아래는 혹시나 나중에 잊어버릴까봐 복붙해놓은 코드!

라이브러리 없이 통신하려니 낯설어서 힘들긴했는데 그래도 해고 나니 라이브러리가 얼마나 삶을 편하게 해주는게 깨닫게 되었다. 

 

class BusinessTabFragment : Fragment() {
    private var _binding: FragmentBusinessTabBinding? = null
    private val binding get() = _binding!!
    private val dataList: MutableList<NewsData> = mutableListOf()
    private val apiKey = BuildConfig.api_key
    private val url = "https://newsapi.org/v2/top-headlines?category=business&country=us"

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View {
        _binding = FragmentBusinessTabBinding.inflate(inflater, container, false)
        return binding.root
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        fetchNewsData()
        setRecyclerView()
    }

    private fun fetchNewsData() {
        lifecycleScope.launch(Dispatchers.IO) {
            val urlConnection = URL(url).openConnection() as? HttpURLConnection
            urlConnection?.apply {
                requestMethod = "GET"
                setRequestProperty("X-Api-Key", apiKey)
                setRequestProperty("User-Agent", "Mozilla/5.0")

                try {
                    if (urlConnection.responseCode == HttpURLConnection.HTTP_OK) {
                        val responseData = urlConnection.inputStream.bufferedReader().use { it.readText() }
                        val jsonObject = JSONObject(responseData)
                        val articlesArray = jsonObject.getJSONArray("articles")

                        val newNewsDataList: MutableList<NewsData> = mutableListOf()

                        for (i in 0 until articlesArray.length()) {
                            val item = articlesArray.getJSONObject(i)
                            val title = item.optString("title", "No Title")
                            val description = item.optString("description", "No Description")
                            val urlToImage = item.optString("urlToImage", "")
                            val publishedAt = item.optString("publishedAt", "")

                            newNewsDataList.add(NewsData(urlToImage, title, description, publishedAt))
                        }
                        withContext(Dispatchers.Main) {
                            dataList.clear()
                            dataList.addAll(newNewsDataList)
                            binding.rvBusiness.adapter?.notifyItemChanged(position)
                        }
                    } else {
                        Log.e("Error", "HTTP Error: ${urlConnection.responseCode}")
                    }
                } catch (e: Exception) {
                    Log.e("Error", "Exception: ${e.message}")
                } finally {
                    urlConnection.disconnect()
                }
            }
        }
    }

    private fun setRecyclerView() {
        val adapter = NewsAdapter(dataList)
        binding.rvBusiness.adapter = adapter
    }

    override fun onDestroyView() {
        super.onDestroyView()
        _binding = null
    }
}

 

2. Gson 

이번에는 Gson 라이브러리를 사용하였다. Gson에는 여러가지 장점있지만 자동매핑 기능이 있다는게 가장 좋은듯하다.

HttpURLConnection 사용하여 Json파일을 불러오고 Gson을 활용해서 자동으로 값이 대입되어 들어가도록 했다.

이렇게 했더니 훨씬 코드가 간결해졌다.

GitHub - google/gson: A Java serialization/deserialization library to convert Java Objects into JSON and back

class BusinessTabFragment : Fragment() {
    private var _binding: FragmentBusinessTabBinding? = null
    private val binding get() = _binding!!
    private var newsList: MutableList<NewsData> = mutableListOf()
    private val apiKey = BuildConfig.api_key

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View {
        _binding = FragmentBusinessTabBinding.inflate(inflater, container, false)
        return binding.root
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        startData()

    }

    private fun startData() {
        lifecycleScope.launch(Dispatchers.IO) {
            val category = getString(R.string.tv_home_business)
            newsList = fetchNewsData(category)
            withContext(Dispatchers.Main) {
                binding.rvBusiness.adapter = NewsAdapter(newsList)
            }
        }
    }

    private fun fetchNewsData(category: String): MutableList<NewsData> {
        val url = URL("https://newsapi.org/v2/top-headlines?category=$category&country=us")
        val urlConnection = (url.openConnection() as? HttpURLConnection)?.apply {
            setRequestProperty("User-Agent", "Mozilla/5.0")
            setRequestProperty("X-Api-Key", apiKey)
            requestMethod = "GET"
        }
        return try {
            when (urlConnection?.responseCode) {
                HttpURLConnection.HTTP_OK -> successHttp(urlConnection)
                HttpURLConnection.HTTP_MOVED_PERM -> showErrorMessage("301오류 URI이 변경 되었습니다.")
                HttpURLConnection.HTTP_NOT_FOUND -> showErrorMessage("404오류 데이터를 가져오는데 실패했습니다.")
                else -> showErrorMessage("네트워크 오류가 발생했습니다.")
            }
        } catch (e: Exception) {
            Log.e("통신오류", "오류가 발생했습니다: ${e.message}")
            mutableListOf()
        } finally {
            urlConnection?.disconnect()
        }
    }

    private fun successHttp(urlConnection: HttpURLConnection): MutableList<NewsData> {
        val gson = Gson()
        val reader = InputStreamReader(urlConnection.inputStream)
        val jsonResponse = gson.fromJson(reader, JsonObject::class.java)
        val articlesJsonArray = jsonResponse.getAsJsonArray("articles")

        return articlesJsonArray.map { gson.fromJson(it, NewsData::class.java) }.toMutableList()
    }

    private fun showErrorMessage(message: String): MutableList<NewsData> {
        lifecycleScope.launch(Dispatchers.Main) {
            Toast.makeText(context, message, Toast.LENGTH_SHORT).show()
        }
        return mutableListOf()
    }

    override fun onDestroyView() {
        super.onDestroyView()
        _binding = null
    }
}

 

3. Retrofit2

retrofit도 문서를 한번 읽어보았고, 최대한 이대로 하려고 했으나 코루틴을 사용하여야 해서 suspend를 사용하였다. 처음에는 retrofit이 어렵다고 생각했는데 계속 사용하다 보니 제일 쉬운듯하다. 

 

여러가지의 @Query가 있을 경우 더더욱 좋다!

API 인터페이스 정의 -> 응답 데이터 클래스 정의 -> Retrofit 인스턴스 생성 및 설정 -> 자동매핑

 

ApiRepository()파일은 나중에 다른 쿼리의 API를 더 불러올지도 몰라서 작성한것인데 단순하게 하나만 불러오는거라면 필요없다. 

Retrofit

interface ApiFetch {

    @Headers("X-Api-Key:$api_key")
    @GET("v2/top-headlines")
    suspend fun getNewsList(@Query("category") category: String, @Query("country") country: String = "us"): Response<NewsResponse>

    companion object {

        fun create(): ApiFetch {
            return Retrofit.Builder()
                .baseUrl("https://newsapi.org")
                .addConverterFactory(GsonConverterFactory.create())
                .build()
                .create(ApiFetch::class.java)
        }
    }
}

class ApiRepository() {
    private val client = ApiFetch.create()

    suspend fun getNewsList(category: String) = client.getNewsList(category)
}

@Parcelize
data class NewsResponse(
    val status: String,
    val totalResults: Int,
    val articles: List<NewsData>
) : Parcelable

@Parcelize
data class NewsData(
    val title: String,
    val content: String,
    val urlToImage: String,
    val publishedAt: String
) : Parcelable

class BusinessTabFragment : Fragment() {

    private var _binding: FragmentBusinessTabBinding? = null
    private val binding get() = _binding!!
    private val netWorkRepository = ApiRepository()
    private var newsList: MutableList<NewsData> = mutableListOf()

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View {
        _binding = FragmentBusinessTabBinding.inflate(inflater, container, false)
        return binding.root
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        startData()
    }

    private fun startData() {
        lifecycleScope.launch(Dispatchers.Main) {
            try {
                val response = withContext(Dispatchers.IO) {
                    netWorkRepository.getNewsList(getString(R.string.home_business))
                }
                if (response.isSuccessful) {
                    response.body()?.articles?.let { newsList.addAll(it) }
                    binding.rvBusiness.adapter = NewsAdapter(newsList)
                } else {
                    httpResponse(response.code(), requireContext())
                }
            } catch (e: Exception) {
                Log.e("startData", "예외 발생: ${e.message}")
            }
        }
    }

    override fun onDestroyView() {
        super.onDestroyView()
        _binding = null
    }

fun httpResponse(responseCode: Int, context: Context) {
    val message = when (responseCode) {
        HttpURLConnection.HTTP_MOVED_PERM -> getString(context, R.string.Extenstion_http_301)
        HttpURLConnection.HTTP_BAD_REQUEST -> getString(context, R.string.Extenstion_http_400)
        HttpURLConnection.HTTP_UNAUTHORIZED -> getString(context, R.string.Extenstion_http_401)
        HttpURLConnection.HTTP_FORBIDDEN -> getString(context, R.string.Extenstion_http_403)
        HttpURLConnection.HTTP_NOT_FOUND -> getString(context, R.string.Extenstion_http_404)
        else -> getString(context, R.string.Extenstion_http_else)
    }
    showToast(message, context)
}

fun getString(context: Context, stringResId: Int): String {
    return context.getString(stringResId)
}

fun showToast(message: String, context: Context) {
    Toast.makeText(context, message, Toast.LENGTH_SHORT).show()
}

 

위에는 suspend를 사용한것이고, 아래는 비동기적으로 불러올 때 사용하는 예시이다.

interface NewsService {

    @GET("/v2/top-headlines")
    fun getTopHeadlines(@Query("category") category: String): Call<List<Article>>

}

// Activity or Fragment 
val newsService = NewsService.create()
newsService.getTopHeadlines("business").enqueue(object : Callback<List<Article>> {
    override fun onResponse(call: Call<List<Article>>, response: Response<List<Article>>) {            
    }

    override fun onFailure(call: Call<List<Article>>, t: Throwable) {
    }
})