[#17] 통신을 위한 네트워크 관련 베이스 코드 작성

- 초기 베이스 코드

app/build.gradle

@@ -71,7 +71,15 @@ dependencies {
     androidTestImplementation 'androidx.test.ext:junit:1.1.3'
     androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'
 
+    // firebase
     implementation platform('com.google.firebase:firebase-bom:29.2.0')
     implementation 'com.google.firebase:firebase-analytics-ktx'
     implementation 'com.google.firebase:firebase-crashlytics-ktx'
+
+    // retrofit2
+    implementation 'com.squareup.retrofit2:retrofit:2.9.0'
+    implementation 'com.squareup.retrofit2:converter-gson:2.9.0'
+
+    // coroutine
+    implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.4.1'
 }

app/src/main/java/com/moyerun/moyeorun_android/MainActivity.kt

@@ -2,10 +2,55 @@ package com.moyerun.moyeorun_android
 
 import androidx.appcompat.app.AppCompatActivity
 import android.os.Bundle
+import com.moyerun.moyeorun_android.common.Lg
+import com.moyerun.moyeorun_android.network.ApiErrorCode
+import com.moyerun.moyeorun_android.network.callAdapter.NetworkResponse
+import com.moyerun.moyeorun_android.network.client.api
+import kotlinx.coroutines.GlobalScope
+import kotlinx.coroutines.launch
 
 class MainActivity : AppCompatActivity() {
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_main)
+
+        apiCallTest()
+    }
+
+    private fun apiCallTest() {
+        GlobalScope.launch {
+            val response1 = api.getUserRepoList("choheeis")
+            when (response1) {
+                is NetworkResponse.Success -> {
+                    Lg.d("getUserRepoList Success") }
+                is NetworkResponse.ApiError -> {
+                    // 비즈니스 로직 상의 에러
+                    // 이넘 클래스로 별도 관리하는 에러 코드와 비교하여 알맞은 로직 작성
+                    val errorCode = response1.code // 이건 상태코드이긴 한데, error 안에 코드 넣어서 보내주는 것 사용.
+                    if (errorCode == ApiErrorCode.NOT_EXIST_USER.code) {
+                        // 에러 대응
+                    }
+                    Lg.d("getUserRepoList ApiError")
+                }
+                is NetworkResponse.NetworkError -> {
+                    // 네트워크 에러와 언논 에러는 전처리되면 좋을 듯
+                    // Success랑 API Error만 뷰 모델에서 관리하도록.
+                    Lg.d("getUserRepoList NetworkError")
+                }
+                is NetworkResponse.UnknownError -> { Lg.d("getUserRepoList UnknownError") }
+            }
+
+            val response2 = api.getAppName()
+            when (response2) {
+                is NetworkResponse.Success -> { Lg.d("getAppName Success") }
+                is NetworkResponse.ApiError -> {
+                    // 비즈니스 로직 상의 에러
+                    // 이넘 클래스로 별도 관리하는 에러 코드와 비교하여 알맞은 로직 작성
+                    Lg.d("getAppName ApiError")
+                }
+                is NetworkResponse.NetworkError -> { Lg.d("getAppName NetworkError") }
+                is NetworkResponse.UnknownError -> { Lg.d("getAppName UnknownError") }
+            }
+        }
     }
 }

app/src/main/java/com/moyerun/moyeorun_android/network/ApiErrorCode.kt

@@ -0,0 +1,5 @@
+package com.moyerun.moyeorun_android.network
+
+enum class ApiErrorCode(val code: Int) {
+    NOT_EXIST_USER(900)
+}

app/src/main/java/com/moyerun/moyeorun_android/network/Response.kt

@@ -0,0 +1,14 @@
+package com.moyerun.moyeorun_android.network
+
+/**
+ * 서버 팀과 합의한 성공/실패 응답 값에 대한 모델입니다.
+ */
+data class Success<T>(
+    val message: String,
+    val data: T
+)
+
+data class Error<T>(
+    val message: String,
+    val error: T
+)

app/src/main/java/com/moyerun/moyeorun_android/network/api/ApiService.kt

@@ -0,0 +1,15 @@
+package com.moyerun.moyeorun_android.network.api
+
+import com.moyerun.moyeorun_android.network.Error
+import com.moyerun.moyeorun_android.network.Success
+import com.moyerun.moyeorun_android.network.callAdapter.NetworkResponse
+import retrofit2.http.GET
+import retrofit2.http.Path
+
+interface ApiService {
+    @GET("users/{user}/repos")
+    suspend fun getUserRepoList(@Path("user") user: String): NetworkResponse<Success<Any>, Error<Any>>
+
+    @GET("appName")
+    suspend fun getAppName(): NetworkResponse<Success<Any>, Error<Any>>
+}

app/src/main/java/com/moyerun/moyeorun_android/network/callAdapter/NetworkResponse.kt

@@ -0,0 +1,10 @@
+package com.moyerun.moyeorun_android.network.callAdapter
+
+import java.io.IOException
+
+sealed class NetworkResponse<out T : Any,out U : Any> {
+    data class Success<T : Any>(val body: T) : NetworkResponse<T, Nothing>()
+    data class ApiError<U : Any>(val body: U, val code: Int) : NetworkResponse<Nothing, U>()
+    data class NetworkError(val error: IOException) : NetworkResponse<Nothing, Nothing>()
+    data class UnknownError(val error: Throwable?) : NetworkResponse<Nothing, Nothing>()
+}

app/src/main/java/com/moyerun/moyeorun_android/network/callAdapter/NetworkResponseAdapterFactory.kt

@@ -0,0 +1,47 @@
+package com.moyerun.moyeorun_android.network.callAdapter
+
+import retrofit2.Call
+import retrofit2.CallAdapter
+import retrofit2.Retrofit
+import java.lang.reflect.ParameterizedType
+import java.lang.reflect.Type
+
+class NetworkResponseAdapterFactory : CallAdapter.Factory() {
+
+    override fun get(
+        returnType: Type,
+        annotations: Array<out Annotation>,
+        retrofit: Retrofit
+    ): CallAdapter<*, *>? {
+
+        // suspend functions wrap the response type in `Call`
+        if (Call::class.java != getRawType(returnType)) {
+            return null
+        }
+
+        // check first that the return type is `ParameterizedType`
+        check(returnType is ParameterizedType) {
+            "return type must be parameterized as Call<Result<Foo>> or Call<Result<out Foo>>"
+        }
+
+        // get the response type inside the `Call` type
+        val responseType = getParameterUpperBound(0, returnType)
+
+        // if the response type is not ApiResponse then we can't handle this type, so we return null
+        if (getRawType(responseType) != NetworkResponse::class.java) {
+            return null
+        }
+
+        // the response type is ApiResponse and should be parameterized
+        check(responseType is ParameterizedType) {
+            "Response must be parameterized as Result<Foo> or Result<out Foo>"
+        }
+
+        val successBodyType = getParameterUpperBound(0, responseType)
+        val errorBodyType = getParameterUpperBound(1, responseType)
+
+        val errorBodyConverter = retrofit.nextResponseBodyConverter<Any>(null, errorBodyType, annotations)
+
+        return NetworkResponseCallAdapter<Any, Any>(successBodyType, errorBodyConverter)
+    }
+}

app/src/main/java/com/moyerun/moyeorun_android/network/callAdapter/NetworkResponseCall.kt

@@ -0,0 +1,94 @@
+package com.moyerun.moyeorun_android.network.callAdapter
+
+import okhttp3.Request
+import okhttp3.ResponseBody
+import okio.Timeout
+import retrofit2.Call
+import retrofit2.Callback
+import retrofit2.Converter
+import retrofit2.Response
+import java.io.IOException
+import java.lang.Exception
+import java.lang.UnsupportedOperationException
+
+internal class NetworkResponseCall<S : Any, E : Any>(
+    private val delegate: Call<S>,
+    private val errorConverter: Converter<ResponseBody, E>
+) : Call<NetworkResponse<S, E>> {
+
+    override fun enqueue(callback: Callback<NetworkResponse<S, E>>) {
+        return delegate.enqueue(object : Callback<S> {
+            override fun onResponse(call: Call<S>, response: Response<S>) {
+                val body = response.body()
+                val code = response.code()
+                val error = response.errorBody()
+
+                if (response.isSuccessful) {
+                    // status code가 200번대 일 때
+                    if (body != null) {
+                        callback.onResponse(
+                            this@NetworkResponseCall,
+                            Response.success(NetworkResponse.Success(body))
+                        )
+                    } else {
+                        // body 없을 때 별도 에러 만들어도 될 듯.
+                        callback.onResponse(
+                            this@NetworkResponseCall,
+                            Response.success(NetworkResponse.UnknownError(null))
+                        )
+                    }
+                } else {
+                    val errorBody = when {
+                        error == null -> null
+                        error.contentLength() == 0L -> null
+                        else -> try {
+                            errorConverter.convert(error)
+                        } catch (e: Exception) {
+                            null
+                        }
+                    }
+
+                    if (errorBody != null) {
+                        callback.onResponse(
+                            this@NetworkResponseCall,
+                            Response.success(NetworkResponse.ApiError(errorBody, code))
+                        )
+                    } else {
+                        callback.onResponse(
+                            this@NetworkResponseCall,
+                            Response.success(NetworkResponse.UnknownError(null))
+                        )
+                    }
+                }
+            }
+
+            override fun onFailure(call: Call<S>, t: Throwable) {
+                val networkResponse = when (t) {
+                    is IOException -> NetworkResponse.NetworkError(t)
+                    else -> NetworkResponse.UnknownError(t)
+                }
+                // 여기서 전처리 하면 됨.
+                callback.onResponse(
+                    this@NetworkResponseCall,
+                    Response.success(networkResponse)
+                )
+            }
+        })
+    }
+
+    override fun clone(): Call<NetworkResponse<S, E>> = NetworkResponseCall(delegate.clone(), errorConverter)
+
+    override fun execute(): Response<NetworkResponse<S, E>> {
+        throw UnsupportedOperationException("NetworkResponseCall doesn't support execute")
+    }
+
+    override fun isExecuted(): Boolean = delegate.isExecuted
+
+    override fun cancel() = delegate.cancel()
+
+    override fun isCanceled(): Boolean = delegate.isCanceled
+
+    override fun request(): Request = delegate.request()
+
+    override fun timeout(): Timeout = delegate.timeout()
+}

app/src/main/java/com/moyerun/moyeorun_android/network/callAdapter/NetworkResponseCallAdapter.kt

@@ -0,0 +1,16 @@
+package com.moyerun.moyeorun_android.network.callAdapter
+
+import okhttp3.ResponseBody
+import retrofit2.Call
+import retrofit2.CallAdapter
+import retrofit2.Converter
+import java.lang.reflect.Type
+
+class NetworkResponseCallAdapter<S : Any, E : Any>(
+    private val successType: Type,
+    private val errorBodyConverter: Converter<ResponseBody, E>
+) : CallAdapter<S, Call<NetworkResponse<S, E>>> {
+    override fun responseType(): Type = successType
+
+    override fun adapt(call: Call<S>): Call<NetworkResponse<S, E>> = NetworkResponseCall(call, errorBodyConverter)
+}

app/src/main/java/com/moyerun/moyeorun_android/network/client/Retrofit.kt

@@ -0,0 +1,16 @@
+package com.moyerun.moyeorun_android.network.client
+
+import com.moyerun.moyeorun_android.network.callAdapter.NetworkResponseAdapterFactory
+import com.moyerun.moyeorun_android.network.api.ApiService
+import retrofit2.Retrofit
+import retrofit2.converter.gson.GsonConverterFactory
+
+private const val BASE_URL = "https://api.github.com/"
+
+private val retrofit: Retrofit = Retrofit.Builder()
+    .baseUrl(BASE_URL)
+    .addCallAdapterFactory(NetworkResponseAdapterFactory())
+    .addConverterFactory(GsonConverterFactory.create())
+    .build()
+
+val api: ApiService = retrofit.create(ApiService::class.java)