[#17] 통신을 위한 네트워크 관련 베이스 코드 작성

- 리뷰 반영
- 레트로핏 버전 변수 정의
- Failure 시 Throwable로 다루도록 변경
- request url 기록
- Exception 구조화

app/build.gradle

@@ -68,6 +68,7 @@ android {
 
 dependencies {
     def glide_version = '4.13.1'
+    def retrofit_version = '2.9.0'
 
     implementation 'androidx.core:core-ktx:1.7.0'
     implementation 'androidx.appcompat:appcompat:1.4.1'
@@ -91,8 +92,8 @@ dependencies {
     annotationProcessor "com.github.bumptech.glide:compiler:$glide_version"
 
     // Retrofit2
-    implementation 'com.squareup.retrofit2:retrofit:2.9.0'
-    implementation 'com.squareup.retrofit2:converter-gson:2.9.0'
+    implementation "com.squareup.retrofit2:retrofit:$retrofit_version"
+    implementation "com.squareup.retrofit2:converter-gson:$retrofit_version"
 
     // Coroutine
     implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-core:1.6.0'

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

@@ -3,7 +3,8 @@ 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.callAdapter.ApiResult
+import com.moyerun.moyeorun_android.common.exceptions.ApiException
+import com.moyerun.moyeorun_android.network.calladapter.ApiResult
 import com.moyerun.moyeorun_android.network.client.apiService
 import kotlinx.coroutines.GlobalScope
 import kotlinx.coroutines.launch
@@ -25,15 +26,23 @@ class MainActivity : AppCompatActivity() {
                     Lg.d("postman test Success response 2 ${response1.body.data}")
                 }
                 is ApiResult.Failure -> {
-                    Lg.d("postman test Failure response 2 ${response1.errorBody.message}")
+                    when (response1.exception) {
+                        is ApiException -> {
+                            Lg.d("postman test Failure response 2 ${response1.exception.message}")
+                        }
+                    }
                 }
             }
             when (response2) {
                 is ApiResult.Success -> {
                     Lg.d("postman test Success response 3 ${response2.body.data}")
                 }
                 is ApiResult.Failure -> {
-                    Lg.d("postman test Failure response 3 ${response2.errorBody.message}")
+                    when (response2.exception) {
+                        is ApiException -> {
+                            Lg.d("postman test Failure response 2 ${response2.exception.message}")
+                        }
+                    }
                 }
             }
         }

app/src/main/java/com/moyerun/moyeorun_android/common/exceptions/ApiException.kt

@@ -0,0 +1,11 @@
+package com.moyerun.moyeorun_android.common.exceptions
+
+import com.moyerun.moyeorun_android.network.api.Error
+
+class ApiException(val url: String, val error: Error) : RuntimeException() {
+    val case: String
+        get() = error.case
+
+    override val message: String?
+        get() = error.message
+}

app/src/main/java/com/moyerun/moyeorun_android/common/exceptions/NetworkException.kt

@@ -0,0 +1,7 @@
+package com.moyerun.moyeorun_android.common.exceptions
+
+import java.lang.RuntimeException
+
+class NetworkException(message: String, cause: Throwable) : RuntimeException(message, cause) {
+
+}

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

@@ -0,0 +1,22 @@
+package com.moyerun.moyeorun_android.network.api
+
+import com.moyerun.moyeorun_android.common.exceptions.ApiException
+
+enum class ApiErrorCase(val case: String) {
+    // 서버와 합의된 에러 케이스들을 정의합니다.
+    NOT_LOGIN("100"), // TODO : 예시입니다. 실제 로그인 작업 시 수정해주세요.
+    UNKNOWN("999");
+
+    companion object {
+        private fun findError(case: String): ApiErrorCase {
+            return values().find { it.case == case } ?: UNKNOWN
+        }
+
+        fun getException(url: String, error: Error, cause: Throwable? = null): Throwable {
+            return when(findError(error.case)) {
+                NOT_LOGIN -> { TODO() }
+                else -> ApiException(url, error)
+            }
+        }
+    }
+}

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

@@ -1,6 +1,6 @@
 package com.moyerun.moyeorun_android.network.api
 
-import com.moyerun.moyeorun_android.network.callAdapter.ApiResult
+import com.moyerun.moyeorun_android.network.calladapter.ApiResult
 import retrofit2.http.GET
 
 interface ApiService {

app/src/main/java/com/moyerun/moyeorun_android/network/calladapter/ApiResult.kt

@@ -1,12 +1,10 @@
-package com.moyerun.moyeorun_android.network.callAdapter
-
-import com.moyerun.moyeorun_android.network.api.Error
+package com.moyerun.moyeorun_android.network.calladapter
 
 /**
  * Success : API 호출 성공 시, body를 Wrapping 합니다.
  * Failure : API 호출 실패 시, errorBody를 Wrpping 합니다.
  */
 sealed class ApiResult<out T> {
     data class Success<T>(val body: T) : ApiResult<T>()
-    data class Failure(val errorBody: Error) : ApiResult<Nothing>()
+    data class Failure(val exception: Throwable) : ApiResult<Nothing>()
 }

app/src/main/java/com/moyerun/moyeorun_android/network/calladapter/ApiResultCall.kt

@@ -1,19 +1,21 @@
-package com.moyerun.moyeorun_android.network.callAdapter
+package com.moyerun.moyeorun_android.network.calladapter
 
+import com.google.gson.Gson
+import com.moyerun.moyeorun_android.common.exceptions.NetworkException
+import com.moyerun.moyeorun_android.network.api.ApiErrorCase
 import com.moyerun.moyeorun_android.network.api.Error
-import com.moyerun.moyeorun_android.network.client.retrofit
 import okhttp3.Request
-import okhttp3.ResponseBody
 import okio.Timeout
 import retrofit2.*
-import java.io.IOException
 
 class ApiResultCall<S>(
     private val delegate: Call<S>
 ) : Call<ApiResult<S>> {
     override fun enqueue(callback: Callback<ApiResult<S>>) {
         delegate.enqueue(object : Callback<S> {
             override fun onResponse(call: Call<S>, response: Response<S>) {
+                val requestUrl = delegate.request().url().toString()
+
                 // status code 200번대.
                 if (response.isSuccessful) {
                     val body = response.body()
@@ -23,47 +25,62 @@ class ApiResultCall<S>(
                             Response.success(ApiResult.Success(body))
                         )
                     } else {
-                        val message = "response body is null."
-                        val case = "001" // TODO : 바디가 null일 경우 합의된 케이스 번호로 변경 필요함. 001은 임시 번호임.
                         callback.onResponse(
                             this@ApiResultCall,
-                            Response.success(ApiResult.Failure(Error(message, case)))
+                            Response.success(
+                                ApiResult.Failure(
+                                    NetworkException(
+                                        "Response from $requestUrl was null " +
+                                                "but response body type was decleared as non-null",
+                                        HttpException(response)
+                                    )
+                                )
+                            )
                         )
                     }
-                } else { // status code 200 아닌 다른 것들.
-                    val errorBody = response.errorBody()?.let { getErrorResponse(it) }
+                } else { // status code 200번대 아님.
+                    val errorBody = response.errorBody()
                     if (errorBody != null) {
+                        val errorResponse = Gson().fromJson(errorBody.string(), Error::class.java)
                         callback.onResponse(
                             this@ApiResultCall,
-                            Response.success(ApiResult.Failure(errorBody))
+                            Response.success(
+                                ApiResult.Failure(
+                                    ApiErrorCase.getException(
+                                        requestUrl,
+                                        errorResponse,
+                                        HttpException(response)
+                                    )
+                                )
+                            )
                         )
                     } else {
-                        val message = "error body is null."
-                        val case = "002" // TODO : 에러 바디가 null일 경우 합의된 케이스 번호로 변경 필요함. 002은 임시 번호임.
                         callback.onResponse(
                             this@ApiResultCall,
-                            Response.success(ApiResult.Failure(Error(message, case)))
+                            Response.success(
+                                ApiResult.Failure(
+                                    NetworkException(
+                                        requestUrl,
+                                        HttpException(response)
+                                    )
+                                )
+                            )
                         )
                     }
                 }
             }
 
-            override fun onFailure(call: Call<S>, t: Throwable) {
-                val networkResponse = when (t) {
-                    is IOException -> {
-                        val message = "network error occurred."
-                        val case = "003" // TODO : 네트워크 에러 발생 시 합의된 케이스 번호로 변경 필요함. 003은 임시 번호임.
-                        Error(message, case)
-                    }
-                    else -> {
-                        val message = "unknown error occurred."
-                        val case = "004" // TODO : 언논 에러 발생 시 합의된 케이스 번호로 변경 필요함. 004는 임시 번호임.
-                        Error(message, case)
-                    }
-                }
+            override fun onFailure(call: Call<S>, throwable: Throwable) {
                 callback.onResponse(
                     this@ApiResultCall,
-                    Response.success(ApiResult.Failure(networkResponse))
+                    Response.success(
+                        ApiResult.Failure(
+                            NetworkException(
+                                call.request().url().toString(),
+                                throwable
+                            )
+                        )
+                    )
                 )
             }
         })
@@ -72,7 +89,7 @@ class ApiResultCall<S>(
     override fun clone(): Call<ApiResult<S>> = ApiResultCall(delegate.clone())
 
     override fun execute(): Response<ApiResult<S>> {
-        throw UnsupportedOperationException("NetworkResponseCall doesn't support execute")
+        throw UnsupportedOperationException("ApiResultCall doesn't support execute")
     }
 
     override fun isExecuted(): Boolean = delegate.isExecuted
@@ -87,10 +104,4 @@ class ApiResultCall<S>(
 
     override fun timeout(): Timeout = delegate.timeout()
 
-    private fun getErrorResponse(errorBody: ResponseBody): Error? {
-        return retrofit.responseBodyConverter<Error>(
-            Error::class.java,
-            Error::class.java.annotations
-        ).convert(errorBody)
-    }
 }

app/src/main/java/com/moyerun/moyeorun_android/network/calladapter/ApiResultCallAdapter.kt

@@ -1,4 +1,4 @@
-package com.moyerun.moyeorun_android.network.callAdapter
+package com.moyerun.moyeorun_android.network.calladapter
 
 import retrofit2.Call
 import retrofit2.CallAdapter

app/src/main/java/com/moyerun/moyeorun_android/network/calladapter/ApiResultCallAdapterFactory.kt

@@ -1,4 +1,4 @@
-package com.moyerun.moyeorun_android.network.callAdapter
+package com.moyerun.moyeorun_android.network.calladapter
 
 import retrofit2.Call
 import retrofit2.CallAdapter

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

@@ -1,6 +1,6 @@
 package com.moyerun.moyeorun_android.network.client
 
-import com.moyerun.moyeorun_android.network.callAdapter.ApiResultCallAdapterFactory
+import com.moyerun.moyeorun_android.network.calladapter.ApiResultCallAdapterFactory
 import com.moyerun.moyeorun_android.network.api.ApiService
 import retrofit2.Retrofit
 import retrofit2.converter.gson.GsonConverterFactory