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A type-safe HTTP client for Android and Java.
/*
* Copyright (C) 2015 Square, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package retrofit2;
import static retrofit2.Utils.getRawType;
import static retrofit2.Utils.methodError;
import java.lang.annotation.Annotation;
import java.lang.reflect.Method;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import javax.annotation.Nullable;
import kotlin.coroutines.Continuation;
import okhttp3.ResponseBody;
/** Adapts an invocation of an interface method into an HTTP call. */
abstract class HttpServiceMethod extends ServiceMethod {
/**
* Inspects the annotations on an interface method to construct a reusable service method that
* speaks HTTP. This requires potentially-expensive reflection so it is best to build each service
* method only once and reuse it.
*/
static HttpServiceMethod parseAnnotations(
Retrofit retrofit, Method method, RequestFactory requestFactory) {
boolean isKotlinSuspendFunction = requestFactory.isKotlinSuspendFunction;
boolean continuationWantsResponse = false;
boolean continuationBodyNullable = false;
Annotation[] annotations = method.getAnnotations();
Type adapterType;
if (isKotlinSuspendFunction) {
Type[] parameterTypes = method.getGenericParameterTypes();
Type responseType =
Utils.getParameterLowerBound(
0, (ParameterizedType) parameterTypes[parameterTypes.length - 1]);
if (getRawType(responseType) == Response.class && responseType instanceof ParameterizedType) {
// Unwrap the actual body type from Response.
responseType = Utils.getParameterUpperBound(0, (ParameterizedType) responseType);
continuationWantsResponse = true;
} else {
// TODO figure out if type is nullable or not
// Metadata metadata = method.getDeclaringClass().getAnnotation(Metadata.class)
// Find the entry for method
// Determine if return type is nullable or not
}
adapterType = new Utils.ParameterizedTypeImpl(null, Call.class, responseType);
annotations = SkipCallbackExecutorImpl.ensurePresent(annotations);
} else {
adapterType = method.getGenericReturnType();
}
CallAdapter callAdapter =
createCallAdapter(retrofit, method, adapterType, annotations);
Type responseType = callAdapter.responseType();
if (responseType == okhttp3.Response.class) {
throw methodError(
method,
"'"
+ getRawType(responseType).getName()
+ "' is not a valid response body type. Did you mean ResponseBody?");
}
if (responseType == Response.class) {
throw methodError(method, "Response must include generic type (e.g., Response)");
}
// TODO support Unit for Kotlin?
if (requestFactory.httpMethod.equals("HEAD") && !Void.class.equals(responseType)) {
throw methodError(method, "HEAD method must use Void as response type.");
}
Converter responseConverter =
createResponseConverter(retrofit, method, responseType);
okhttp3.Call.Factory callFactory = retrofit.callFactory;
if (!isKotlinSuspendFunction) {
return new CallAdapted<>(requestFactory, callFactory, responseConverter, callAdapter);
} else if (continuationWantsResponse) {
//noinspection unchecked Kotlin compiler guarantees ReturnT to be Object.
return (HttpServiceMethod)
new SuspendForResponse<>(
requestFactory,
callFactory,
responseConverter,
(CallAdapter>) callAdapter);
} else {
//noinspection unchecked Kotlin compiler guarantees ReturnT to be Object.
return (HttpServiceMethod)
new SuspendForBody<>(
requestFactory,
callFactory,
responseConverter,
(CallAdapter>) callAdapter,
continuationBodyNullable);
}
}
private static CallAdapter createCallAdapter(
Retrofit retrofit, Method method, Type returnType, Annotation[] annotations) {
try {
//noinspection unchecked
return (CallAdapter) retrofit.callAdapter(returnType, annotations);
} catch (RuntimeException e) { // Wide exception range because factories are user code.
throw methodError(method, e, "Unable to create call adapter for %s", returnType);
}
}
private static Converter createResponseConverter(
Retrofit retrofit, Method method, Type responseType) {
Annotation[] annotations = method.getAnnotations();
try {
return retrofit.responseBodyConverter(responseType, annotations);
} catch (RuntimeException e) { // Wide exception range because factories are user code.
throw methodError(method, e, "Unable to create converter for %s", responseType);
}
}
private final RequestFactory requestFactory;
private final okhttp3.Call.Factory callFactory;
private final Converter responseConverter;
HttpServiceMethod(
RequestFactory requestFactory,
okhttp3.Call.Factory callFactory,
Converter responseConverter) {
this.requestFactory = requestFactory;
this.callFactory = callFactory;
this.responseConverter = responseConverter;
}
@Override
final @Nullable ReturnT invoke(Object[] args) {
Call call = new OkHttpCall<>(requestFactory, args, callFactory, responseConverter);
return adapt(call, args);
}
protected abstract @Nullable ReturnT adapt(Call call, Object[] args);
static final class CallAdapted extends HttpServiceMethod {
private final CallAdapter callAdapter;
CallAdapted(
RequestFactory requestFactory,
okhttp3.Call.Factory callFactory,
Converter responseConverter,
CallAdapter callAdapter) {
super(requestFactory, callFactory, responseConverter);
this.callAdapter = callAdapter;
}
@Override
protected ReturnT adapt(Call call, Object[] args) {
return callAdapter.adapt(call);
}
}
static final class SuspendForResponse extends HttpServiceMethod {
private final CallAdapter> callAdapter;
SuspendForResponse(
RequestFactory requestFactory,
okhttp3.Call.Factory callFactory,
Converter responseConverter,
CallAdapter> callAdapter) {
super(requestFactory, callFactory, responseConverter);
this.callAdapter = callAdapter;
}
@Override
protected Object adapt(Call call, Object[] args) {
call = callAdapter.adapt(call);
//noinspection unchecked Checked by reflection inside RequestFactory.
Continuation> continuation =
(Continuation>) args[args.length - 1];
// See SuspendForBody for explanation about this try/catch.
try {
return KotlinExtensions.awaitResponse(call, continuation);
} catch (Exception e) {
return KotlinExtensions.suspendAndThrow(e, continuation);
}
}
}
static final class SuspendForBody extends HttpServiceMethod {
private final CallAdapter> callAdapter;
private final boolean isNullable;
SuspendForBody(
RequestFactory requestFactory,
okhttp3.Call.Factory callFactory,
Converter responseConverter,
CallAdapter> callAdapter,
boolean isNullable) {
super(requestFactory, callFactory, responseConverter);
this.callAdapter = callAdapter;
this.isNullable = isNullable;
}
@Override
protected Object adapt(Call call, Object[] args) {
call = callAdapter.adapt(call);
//noinspection unchecked Checked by reflection inside RequestFactory.
Continuation continuation = (Continuation) args[args.length - 1];
// Calls to OkHttp Call.enqueue() like those inside await and awaitNullable can sometimes
// invoke the supplied callback with an exception before the invoking stack frame can return.
// Coroutines will intercept the subsequent invocation of the Continuation and throw the
// exception synchronously. A Java Proxy cannot throw checked exceptions without them being
// declared on the interface method. To avoid the synchronous checked exception being wrapped
// in an UndeclaredThrowableException, it is intercepted and supplied to a helper which will
// force suspension to occur so that it can be instead delivered to the continuation to
// bypass this restriction.
try {
return isNullable
? KotlinExtensions.awaitNullable(call, continuation)
: KotlinExtensions.await(call, continuation);
} catch (Exception e) {
return KotlinExtensions.suspendAndThrow(e, continuation);
}
}
}
}