Implement Json decoding using streaming API

retrofit-converters/kotlinx-serialization-json/src/main/java/retrofit2/converter/kotlinx/serialization/json/JsonConverterFactory.kt

@@ -1,10 +1,10 @@
 package retrofit2.converter.kotlinx.serialization.json
 
+import kotlinx.serialization.ExperimentalSerializationApi
 import kotlinx.serialization.json.Json
 import okhttp3.MediaType
 import retrofit2.Converter
 import retrofit2.converter.kotlinx.serialization.Factory
-import retrofit2.converter.kotlinx.serialization.Serializer
 
 /**
  * Return a [Converter.Factory] which uses Kotlin serialization for Json-based payloads.
@@ -13,8 +13,9 @@ import retrofit2.converter.kotlinx.serialization.Serializer
  * that it can handle all types. If you are mixing this with something else, you must add this
  * instance last to allow the other converters a chance to see their types.
  */
+@ExperimentalSerializationApi
 @JvmName("create")
 fun Json.asConverterFactory(): Converter.Factory {
   val contentType = MediaType.get("application/json; charset=UTF-8")
-  return Factory(contentType, Serializer.FromString(this))
+  return Factory(contentType, SerializerFromJson(this))
 }

retrofit-converters/kotlinx-serialization-json/src/main/java/retrofit2/converter/kotlinx/serialization/json/SerializerFromJson.kt

@@ -0,0 +1,24 @@
+package retrofit2.converter.kotlinx.serialization.json
+
+import kotlinx.serialization.DeserializationStrategy
+import kotlinx.serialization.ExperimentalSerializationApi
+import kotlinx.serialization.SerializationStrategy
+import kotlinx.serialization.json.Json
+import kotlinx.serialization.json.decodeFromStream
+import okhttp3.MediaType
+import okhttp3.RequestBody
+import okhttp3.ResponseBody
+import retrofit2.converter.kotlinx.serialization.Serializer
+
+@ExperimentalSerializationApi
+class SerializerFromJson(override val format: Json) : Serializer() {
+  override fun <T> fromResponseBody(loader: DeserializationStrategy<T>, body: ResponseBody): T {
+    val stream = body.byteStream()
+    return format.decodeFromStream(loader, stream)
+  }
+
+  override fun <T> toRequestBody(contentType: MediaType, saver: SerializationStrategy<T>, value: T): RequestBody {
+    val string = format.encodeToString(saver, value)
+    return RequestBody.create(contentType, string)
+  }
+}

retrofit-converters/kotlinx-serialization-json/src/test/java/retrofit2/converter/kotlinx/serialization/json/KotlinxJsonSerializationConverterFactoryContextualListTest.kt

@@ -1,5 +1,6 @@
 package retrofit2.converter.kotlinx.serialization.json
 
+import kotlinx.serialization.ExperimentalSerializationApi
 import kotlinx.serialization.KSerializer
 import kotlinx.serialization.Serializable
 import kotlinx.serialization.descriptors.PrimitiveKind
@@ -21,6 +22,7 @@ import retrofit2.http.Body
 import retrofit2.http.GET
 import retrofit2.http.POST
 
+@OptIn(ExperimentalSerializationApi::class)
 class KotlinxJsonSerializationConverterFactoryContextualListTest {
   @get:Rule
   val server = MockWebServer()

retrofit-converters/kotlinx-serialization-json/src/test/java/retrofit2/converter/kotlinx/serialization/json/KotlinxSerializationJsonConverterFactoryContextualTest.kt

@@ -1,5 +1,6 @@
 package retrofit2.converter.kotlinx.serialization.json
 
+import kotlinx.serialization.ExperimentalSerializationApi
 import kotlinx.serialization.KSerializer
 import kotlinx.serialization.Serializable
 import kotlinx.serialization.descriptors.PrimitiveKind
@@ -21,6 +22,7 @@ import retrofit2.http.Body
 import retrofit2.http.GET
 import retrofit2.http.POST
 
+@OptIn(ExperimentalSerializationApi::class)
 class KotlinxSerializationJsonConverterFactoryContextualTest {
   @get:Rule
   val server = MockWebServer()

retrofit-converters/kotlinx-serialization-json/src/test/java/retrofit2/converter/kotlinx/serialization/json/KotlinxSerializationJsonConverterFactoryTest.kt

@@ -1,5 +1,6 @@
 package retrofit2.converter.kotlinx.serialization.json
 
+import kotlinx.serialization.ExperimentalSerializationApi
 import kotlinx.serialization.Serializable
 import kotlinx.serialization.json.Json
 import okhttp3.mockwebserver.MockResponse
@@ -14,6 +15,7 @@ import retrofit2.http.Body
 import retrofit2.http.GET
 import retrofit2.http.POST
 
+@OptIn(ExperimentalSerializationApi::class)
 class KotlinxSerializationJsonConverterFactoryTest {
   @get:Rule val server = MockWebServer()