/
GuavaCallAdapterFactory.java
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/
GuavaCallAdapterFactory.java
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/*
* Copyright (C) 2016 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.guava;
import com.google.common.util.concurrent.AbstractFuture;
import com.google.common.util.concurrent.ListenableFuture;
import java.io.IOException;
import java.lang.annotation.Annotation;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import retrofit2.Call;
import retrofit2.CallAdapter;
import retrofit2.Callback;
import retrofit2.Response;
import retrofit2.Retrofit;
/**
* A {@linkplain CallAdapter.Factory call adapter} which creates Guava futures.
* <p>
* Adding this class to {@link Retrofit} allows you to return {@link ListenableFuture} from service
* methods.
* <pre><code>
* interface MyService {
* @GET("user/me")
* ListenableFuture<User> getUser()
* }
* </code></pre>
* There are two configurations supported for the {@code ListenableFuture} type parameter:
* <ul>
* <li>Direct body (e.g., {@code ListenableFuture<User>}) returns the deserialized body for 2XX
* responses, sets {@link HttpException} errors for non-2XX responses, and sets {@link IOException}
* for network errors.</li>
* <li>Response wrapped body (e.g., {@code ListenableFuture<Response<User>>}) returns a
* {@link Response} object for all HTTP responses and sets {@link IOException} for network
* errors</li>
* </ul>
*/
public final class GuavaCallAdapterFactory extends CallAdapter.Factory {
public static GuavaCallAdapterFactory create() {
return new GuavaCallAdapterFactory();
}
private GuavaCallAdapterFactory() {
}
@Override
public CallAdapter<?> get(Type returnType, Annotation[] annotations, Retrofit retrofit) {
if (getRawType(returnType) != ListenableFuture.class) {
return null;
}
if (!(returnType instanceof ParameterizedType)) {
throw new IllegalStateException("ListenableFuture return type must be parameterized"
+ " as ListenableFuture<Foo> or ListenableFuture<? extends Foo>");
}
Type innerType = getParameterUpperBound(0, (ParameterizedType) returnType);
if (getRawType(innerType) != Response.class) {
// Generic type is not Response<T>. Use it for body-only adapter.
return new BodyCallAdapter(innerType);
}
// Generic type is Response<T>. Extract T and create the Response version of the adapter.
if (!(innerType instanceof ParameterizedType)) {
throw new IllegalStateException("Response must be parameterized"
+ " as Response<Foo> or Response<? extends Foo>");
}
Type responseType = getParameterUpperBound(0, (ParameterizedType) innerType);
return new ResponseCallAdapter(responseType);
}
private static class BodyCallAdapter implements CallAdapter<ListenableFuture<?>> {
private final Type responseType;
BodyCallAdapter(Type responseType) {
this.responseType = responseType;
}
@Override public Type responseType() {
return responseType;
}
@Override public <R> ListenableFuture<R> adapt(final Call<R> call) {
return new AbstractFuture<R>() {
{
call.enqueue(new Callback<R>() {
@Override public void onResponse(Call<R> call, Response<R> response) {
if (response.isSuccessful()) {
set(response.body());
} else {
setException(new HttpException(response));
}
}
@Override public void onFailure(Call<R> call, Throwable t) {
setException(t);
}
});
}
@Override protected void interruptTask() {
call.cancel();
}
};
}
}
private static class ResponseCallAdapter implements CallAdapter<ListenableFuture<?>> {
private final Type responseType;
ResponseCallAdapter(Type responseType) {
this.responseType = responseType;
}
@Override public Type responseType() {
return responseType;
}
@Override public <R> ListenableFuture<Response<R>> adapt(final Call<R> call) {
return new AbstractFuture<Response<R>>() {
{
call.enqueue(new Callback<R>() {
@Override public void onResponse(Call<R> call, Response<R> response) {
set(response);
}
@Override public void onFailure(Call<R> call, Throwable t) {
setException(t);
}
});
}
@Override protected void interruptTask() {
call.cancel();
}
};
}
}
}