retrofit2.adapter.rxjava.RxJavaCallAdapterFactory Maven / Gradle / Ivy
/*
* 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.adapter.rxjava;
import java.lang.annotation.Annotation;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.concurrent.atomic.AtomicBoolean;
import retrofit2.Call;
import retrofit2.CallAdapter;
import retrofit2.Response;
import retrofit2.Retrofit;
import rx.Observable;
import rx.Producer;
import rx.Scheduler;
import rx.Subscriber;
import rx.exceptions.Exceptions;
import rx.functions.Action0;
import rx.functions.Func1;
import rx.subscriptions.Subscriptions;
/**
* A {@linkplain CallAdapter.Factory call adapter} which uses RxJava for creating observables.
*
* Adding this class to {@link Retrofit} allows you to return {@link Observable} from service
* methods.
*
{@code
* interface MyService {
* @GET("user/me")
* Observable getUser()
* }
* }
*/
public final class RxJavaCallAdapterFactory extends CallAdapter.Factory {
/**
* Returns an instance which creates synchronous observables that do not operate on any scheduler
* by default.
*/
public static RxJavaCallAdapterFactory create() {
return new RxJavaCallAdapterFactory(null);
}
/**
* Returns an instance which creates synchronous observables that
* {@linkplain Observable#subscribeOn(Scheduler) subscribe on} {@code scheduler} by default.
*/
public static RxJavaCallAdapterFactory createWithScheduler(Scheduler scheduler) {
if (scheduler == null) throw new NullPointerException("scheduler == null");
return new RxJavaCallAdapterFactory(scheduler);
}
private final Scheduler scheduler;
private RxJavaCallAdapterFactory(Scheduler scheduler) {
this.scheduler = scheduler;
}
@Override
public CallAdapter get(Type returnType, Annotation[] annotations, Retrofit retrofit) {
Class rawType = getRawType(returnType);
String canonicalName = rawType.getCanonicalName();
boolean isSingle = "rx.Single".equals(canonicalName);
boolean isCompletable = "rx.Completable".equals(canonicalName);
if (rawType != Observable.class && !isSingle && !isCompletable) {
return null;
}
if (!isCompletable && !(returnType instanceof ParameterizedType)) {
String name = isSingle ? "Single" : "Observable";
throw new IllegalStateException(name + " return type must be parameterized"
+ " as " + name + " or " + name + "");
}
if (isCompletable) {
// Add Completable-converter wrapper from a separate class. This defers classloading such that
// regular Observable operation can be leveraged without relying on this unstable RxJava API.
// Note that this has to be done separately since Completable doesn't have a parametrized
// type.
return CompletableHelper.createCallAdapter(scheduler);
}
CallAdapter> callAdapter = getCallAdapter(returnType, scheduler);
if (isSingle) {
// Add Single-converter wrapper from a separate class. This defers classloading such that
// regular Observable operation can be leveraged without relying on this unstable RxJava API.
return SingleHelper.makeSingle(callAdapter);
}
return callAdapter;
}
private CallAdapter> getCallAdapter(Type returnType, Scheduler scheduler) {
Type observableType = getParameterUpperBound(0, (ParameterizedType) returnType);
Class rawObservableType = getRawType(observableType);
if (rawObservableType == Response.class) {
if (!(observableType instanceof ParameterizedType)) {
throw new IllegalStateException("Response must be parameterized"
+ " as Response or Response");
}
Type responseType = getParameterUpperBound(0, (ParameterizedType) observableType);
return new ResponseCallAdapter(responseType, scheduler);
}
if (rawObservableType == Result.class) {
if (!(observableType instanceof ParameterizedType)) {
throw new IllegalStateException("Result must be parameterized"
+ " as Result or Result");
}
Type responseType = getParameterUpperBound(0, (ParameterizedType) observableType);
return new ResultCallAdapter(responseType, scheduler);
}
return new SimpleCallAdapter(observableType, scheduler);
}
static final class CallOnSubscribe implements Observable.OnSubscribe> {
private final Call originalCall;
CallOnSubscribe(Call originalCall) {
this.originalCall = originalCall;
}
@Override public void call(final Subscriber> subscriber) {
// Since Call is a one-shot type, clone it for each new subscriber.
Call call = originalCall.clone();
// Wrap the call in a helper which handles both unsubscription and backpressure.
RequestArbiter requestArbiter = new RequestArbiter<>(call, subscriber);
subscriber.add(Subscriptions.create(requestArbiter));
subscriber.setProducer(requestArbiter);
}
}
static final class RequestArbiter extends AtomicBoolean implements Action0, Producer {
private final Call call;
private final Subscriber> subscriber;
RequestArbiter(Call call, Subscriber> subscriber) {
this.call = call;
this.subscriber = subscriber;
}
@Override public void request(long n) {
if (n < 0) throw new IllegalArgumentException("n < 0: " + n);
if (n == 0) return; // Nothing to do when requesting 0.
if (!compareAndSet(false, true)) return; // Request was already triggered.
try {
Response response = call.execute();
if (!subscriber.isUnsubscribed()) {
subscriber.onNext(response);
}
} catch (Throwable t) {
Exceptions.throwIfFatal(t);
if (!subscriber.isUnsubscribed()) {
subscriber.onError(t);
}
return;
}
if (!subscriber.isUnsubscribed()) {
subscriber.onCompleted();
}
}
@Override public void call() {
call.cancel();
}
}
static final class ResponseCallAdapter implements CallAdapter> {
private final Type responseType;
private final Scheduler scheduler;
ResponseCallAdapter(Type responseType, Scheduler scheduler) {
this.responseType = responseType;
this.scheduler = scheduler;
}
@Override public Type responseType() {
return responseType;
}
@Override public Observable> adapt(Call call) {
Observable> observable = Observable.create(new CallOnSubscribe<>(call));
if (scheduler != null) {
return observable.subscribeOn(scheduler);
}
return observable;
}
}
static final class SimpleCallAdapter implements CallAdapter> {
private final Type responseType;
private final Scheduler scheduler;
SimpleCallAdapter(Type responseType, Scheduler scheduler) {
this.responseType = responseType;
this.scheduler = scheduler;
}
@Override public Type responseType() {
return responseType;
}
@Override public Observable adapt(Call call) {
Observable observable = Observable.create(new CallOnSubscribe<>(call)) //
.lift(OperatorMapResponseToBodyOrError.instance());
if (scheduler != null) {
return observable.subscribeOn(scheduler);
}
return observable;
}
}
static final class ResultCallAdapter implements CallAdapter> {
private final Type responseType;
private final Scheduler scheduler;
ResultCallAdapter(Type responseType, Scheduler scheduler) {
this.responseType = responseType;
this.scheduler = scheduler;
}
@Override public Type responseType() {
return responseType;
}
@Override public Observable> adapt(Call call) {
Observable> observable = Observable.create(new CallOnSubscribe<>(call)) //
.map(new Func1, Result>() {
@Override public Result call(Response response) {
return Result.response(response);
}
}).onErrorReturn(new Func1>() {
@Override public Result call(Throwable throwable) {
return Result.error(throwable);
}
});
if (scheduler != null) {
return observable.subscribeOn(scheduler);
}
return observable;
}
}
}