这是适配器的一个工作示例，该适配器自动将响应
Result包装到包装器中。GitHub示例也可用。
// build.gradle...dependencies { implementation 'com.squareup.retrofit2:retrofit:2.6.1' implementation 'com.squareup.retrofit2:converter-gson:2.6.1' implementation 'com.google.pre.gson:gson:2.8.5'}// test.kt...sealed class Result<out T> { data class Success<T>(val data: T?) : Result<T>() data class Failure(val statusCode: Int?) : Result<Nothing>() object NetworkError : Result<Nothing>()}data class Bar( @SerializedName("foo") val foo: String)interface Service { @GET("bar") suspend fun getBar(): Result<Bar> @GET("bars") suspend fun getBars(): Result<List<Bar>>}abstract class CallDelegate<TIn, TOut>( protected val proxy: Call<TIn>) : Call<TOut> { override fun execute(): Response<TOut> = throw NotImplementedError() override final fun enqueue(callback: Callback<TOut>) = enqueueImpl(callback) override final fun clone(): Call<TOut> = cloneImpl() override fun cancel() = proxy.cancel() override fun request(): Request = proxy.request() override fun isExecuted() = proxy.isExecuted override fun isCanceled() = proxy.isCanceled abstract fun enqueueImpl(callback: Callback<TOut>) abstract fun cloneImpl(): Call<TOut>}class ResultCall<T>(proxy: Call<T>) : CallDelegate<T, Result<T>>(proxy) { override fun enqueueImpl(callback: Callback<Result<T>>) = proxy.enqueue(object: Callback<T> { override fun onResponse(call: Call<T>, response: Response<T>) { val pre = response.pre() val result = if (pre in 200 until 300) { val body = response.body() Result.Success(body) } else { Result.Failure(pre) } callback.onResponse(this@ResultCall, Response.success(result)) } override fun onFailure(call: Call<T>, t: Throwable) { val result = if (t is IOException) { Result.NetworkError } else { Result.Failure(null) } callback.onResponse(this@ResultCall, Response.success(result)) } }) override fun cloneImpl() = ResultCall(proxy.clone())}class ResultAdapter( private val type: Type): CallAdapter<Type, Call<Result<Type>>> { override fun responseType() = type override fun adapt(call: Call<Type>): Call<Result<Type>> = ResultCall(call)}class MyCallAdapterFactory : CallAdapter.Factory() { override fun get( returnType: Type, annotations: Array<Annotation>, retrofit: Retrofit ) = when (getRawType(returnType)) { Call::class.java -> { val callType = getParameterUpperBound(0, returnType as ParameterizedType) when (getRawType(callType)) { Result::class.java -> { val resultType = getParameterUpperBound(0, callType as ParameterizedType) ResultAdapter(resultType) } else -> null } } else -> null }}class MockInterceptor : Interceptor { override fun intercept(chain: Interceptor.Chain): okhttp3.Response { val response = when (chain.request().url().enpredPath()) { "/bar" -> """{"foo":"baz"}""" "/bars" -> """[{"foo":"baz1"},{"foo":"baz2"}]""" else -> throw Error("unknown request") } val mediaType = MediaType.parse("application/json") val responseBody = ResponseBody.create(mediaType, response) return okhttp3.Response.Builder() .protocol(Protocol.HTTP_1_0) .request(chain.request()) .pre(200) .message("") .body(responseBody) .build() }}suspend fun test() { val mockInterceptor = MockInterceptor() val mockClient = OkHttpClient.Builder() .addInterceptor(mockInterceptor) .build() val retrofit = Retrofit.Builder() .baseUrl("https://mock.com/") .client(mockClient) .addCallAdapterFactory(MyCallAdapterFactory()) .addConverterFactory(GsonConverterFactory.create()) .build() val service = retrofit.create(Service::class.java) val bar = service.getBar() val bars = service.getBars() ...}...
