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Demonstrate HTTP caching with OkHttp and Retrofit.
/*
* Copyright (C) 2013 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.
*/
import com.google.mockwebserver.MockResponse;
import com.google.mockwebserver.MockWebServer;
import com.squareup.okhttp.HttpResponseCache;
import com.squareup.okhttp.OkHttpClient;
import java.io.File;
import java.util.UUID;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;
import retrofit.RestAdapter;
import retrofit.client.OkClient;
import retrofit.http.GET;
import retrofit.http.Path;
import static org.fest.assertions.api.Assertions.assertThat;
public class RetrofitCachingExample {
interface SodaService {
@GET("/{brand}") Object cola(@Path("brand") String brand);
}
public static void main(String[] args) throws Exception {
// Create a web server. MockWebServer is good. Use it.
MockWebServer mockWebServer = new MockWebServer();
mockWebServer.play();
// Create an HTTP client that uses a cache on the file system. Android applications should use
// their Context to get a cache directory.
OkHttpClient okHttpClient = new OkHttpClient();
File cacheDir = new File(System.getProperty("java.io.tmpdir"), UUID.randomUUID().toString());
HttpResponseCache cache = new HttpResponseCache(cacheDir, 1024);
okHttpClient.setResponseCache(cache);
// Create a Retrofit RestAdapter for our SodaService interface.
Executor executor = Executors.newCachedThreadPool();
RestAdapter restAdapter = new RestAdapter.Builder()
.setExecutors(executor, executor)
.setClient(new OkClient(okHttpClient))
.setServer(mockWebServer.getUrl("/").toString())
.build();
SodaService sodaService = restAdapter.create(SodaService.class);
// /pepsi hits the web server and returns a response that will be fully cached for 60 seconds.
mockWebServer.enqueue(new MockResponse()
.addHeader("Cache-Control: max-age=60")
.setBody("\"You got the right one, baby\""));
assertThat(sodaService.cola("pepsi")).isEqualTo("You got the right one, baby");
assertThat(cache.getRequestCount()).isEqualTo(1);
assertThat(cache.getNetworkCount()).isEqualTo(1);
assertThat(cache.getHitCount()).isEqualTo(0);
// /coke hits the web server and returns a response that will be conditionally cached.
mockWebServer.enqueue(new MockResponse()
.addHeader("ETag: v1")
.setBody("\"Always Coca-Cola\""));
assertThat(sodaService.cola("coke")).isEqualTo("Always Coca-Cola");
assertThat(cache.getRequestCount()).isEqualTo(2);
assertThat(cache.getNetworkCount()).isEqualTo(2);
assertThat(cache.getHitCount()).isEqualTo(0);
// /pepsi returns a response from the cache.
assertThat(sodaService.cola("pepsi")).isEqualTo("You got the right one, baby");
assertThat(cache.getRequestCount()).isEqualTo(3);
assertThat(cache.getNetworkCount()).isEqualTo(2);
assertThat(cache.getHitCount()).isEqualTo(1);
// /coke validates the cached response. The server says the cached version is still good.
mockWebServer.enqueue(new MockResponse()
.setResponseCode(304));
assertThat(sodaService.cola("coke")).isEqualTo("Always Coca-Cola");
assertThat(cache.getRequestCount()).isEqualTo(4);
assertThat(cache.getNetworkCount()).isEqualTo(3);
assertThat(cache.getHitCount()).isEqualTo(2);
mockWebServer.shutdown();
}
}
@osrl

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commented May 1, 2014

Hello,
Is there anything else i should do to make it work offline?

I've already fallowed your gist. But i get RetrofitError (UnknownHostException)

I've asked a SO question here: http://stackoverflow.com/questions/23429046/can-retrofit-with-okhttp-can-use-cache-data-when-offline

@feresr

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commented May 27, 2014

In android, how do I get access to a context if I'm not creating my API client on an activity (why would I?)

@bidrohi

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commented Aug 6, 2014

feresr, you would use the application context.

@ryancford

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commented Sep 15, 2015

Or pass context as an argument.

@markshiz

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commented Oct 5, 2015

@swankjesse I realize this is an old gist, but I am so confused. I implemented this test with the latest version of OkHttpClient, 2.5.0, and it passes, but the logging for the ETag request is bogus. The logged response always shows 200, and I never see the ETag being sent in the request. What is going on here? What should I trust? Do I need to break out the http proxy? 😃

See: https://gist.github.com/markshiz/5cfe5546c5ec5cfbd309

EDIT:

See this tweet for explanation: https://twitter.com/JakeWharton/status/651220291763331073
TL;DR: Logging in Retrofit v1 is an approximation.

@ncornette

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commented Jun 23, 2016

See this test : https://github.com/ncornette/OkCacheControl/blob/master/okcache-control/src/test/java/com/ncornette/cache/OkCacheControlTest.java

The lib also solves @feresr point about not passing the context, it uses a callback to ask for network state

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