使用Retrofit 2.0.x进行HTTP缓存 [英] HTTP Caching with Retrofit 2.0.x
本文介绍了使用Retrofit 2.0.x进行HTTP缓存的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我正在尝试使用Retrofit 2.0在我的应用程序中缓存一些响应,但是我缺少一些东西.
I'm trying to cache some responses in my app using Retrofit 2.0, but I'm missing something.
我安装了一个缓存文件,如下所示:
I installed a caching file as follows:
private static File httpCacheDir;
private static Cache cache;
try {
httpCacheDir = new File(getApplicationContext().getCacheDir(), "http");
httpCacheDir.setReadable(true);
long httpCacheSize = 10 * 1024 * 1024; // 10 MiB
HttpResponseCache.install(httpCacheDir, httpCacheSize);
cache = new Cache(httpCacheDir, httpCacheSize);
Log.i("HTTP Caching", "HTTP response cache installation success");
} catch (IOException e) {
Log.i("HTTP Caching", "HTTP response cache installation failed:" + e);
}
public static Cache getCache() {
return cache;
}
在/data/user/0/<PackageNmae>/cache/http
中创建文件
,然后准备了一个网络拦截器,如下所示:
which creates a file in /data/user/0/<PackageNmae>/cache/http
, then prepared a network interceptor as follows:
public class CachingControlInterceptor implements Interceptor {
@Override
public Response intercept(Chain chain) throws IOException {
Request request = chain.request();
// Add Cache Control only for GET methods
if (request.method().equals("GET")) {
if (ConnectivityUtil.checkConnectivity(getContext())) {
// 1 day
request.newBuilder()
.header("Cache-Control", "only-if-cached")
.build();
} else {
// 4 weeks stale
request.newBuilder()
.header("Cache-Control", "public, max-stale=2419200")
.build();
}
}
Response originalResponse = chain.proceed(chain.request());
return originalResponse.newBuilder()
.header("Cache-Control", "max-age=86400")
.build();
}
}
我的Retrofit
和OkHttpClient
实例:
OkHttpClient client = new OkHttpClient();
client.setCache(getCache());
client.interceptors().add(new MainInterceptor());
client.interceptors().add(new LoggingInceptor());
client.networkInterceptors().add(new CachingControlInterceptor());
Retrofit restAdapter = new Retrofit.Builder()
.client(client)
.baseUrl(Constants.BASE_URL)
.addConverterFactory(GsonConverterFactory.create(gson))
.build();
productsService = restAdapter.create(ProductsService.class);
其中ProductsService.class
包含:
@Headers("Cache-Control: max-age=86400")
@GET("categories/")
Call<PagedResponse<Category>> listCategories();
和
Call<PagedResponse<Category>> call = getRestClient().getProductsService().listCategories();
call.enqueue(new GenericCallback<PagedResponse<Category>>() {
// whatever
// GenericCallback<T> implements Callback<T>
}
});
这里的问题是:设备离线时如何使它访问缓存的响应?
The question here is: How to make it access cached responses when device being offline?
后端响应的标头是:
Allow → GET, HEAD, OPTIONS
Cache-Control → max-age=86400, must-revalidate
Connection → keep-alive
Content-Encoding → gzip
Content-Language → en
Content-Type → application/json; charset=utf-8
Date → Thu, 17 Dec 2015 09:42:49 GMT
Server → nginx
Transfer-Encoding → chunked
Vary → Accept-Encoding, Cookie, Accept-Language
X-Frame-Options → SAMEORIGIN
x-content-type-options → nosniff
x-xss-protection → 1; mode=block
推荐答案
最后,我得到了答案.
Finally I get the answer.
网络拦截器应如下:
public class CachingControlInterceptor implements Interceptor {
@Override
public Response intercept(Chain chain) throws IOException {
Request request = chain.request();
// Add Cache Control only for GET methods
if (request.method().equals("GET")) {
if (ConnectivityUtil.checkConnectivity(YaootaApplication.getContext())) {
// 1 day
request = request.newBuilder()
.header("Cache-Control", "only-if-cached")
.build();
} else {
// 4 weeks stale
request = request.newBuilder()
.header("Cache-Control", "public, max-stale=2419200")
.build();
}
}
Response originalResponse = chain.proceed(request);
return originalResponse.newBuilder()
.header("Cache-Control", "max-age=600")
.build();
}
}
然后安装缓存文件就这么简单
then installing cache file is that simple
long SIZE_OF_CACHE = 10 * 1024 * 1024; // 10 MiB
Cache cache = new Cache(new File(context.getCacheDir(), "http"), SIZE_OF_CACHE);
OkHttpClient client = new OkHttpClient();
client.cache(cache);
client.networkInterceptors().add(new CachingControlInterceptor());
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