使用Retrofit 2.0.x的HTTP缓存
使用Retrofit 2.0.x的HTTP缓存
提问于 2015-12-16 19:38:38
我试图使用Retrofit 2.0在我的应用程序中缓存一些响应，但我遗漏了一些东西。
我安装了缓存文件，如下所示：
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;
}它在/data/user/0/<PackageNmae>/cache/http中创建了一个文件，然后准备了一个网络拦截器，如下所示：
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:如何让它在设备脱机时访问缓存的响应？
后端响应头部为：
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回答 4
Stack Overflow用户
回答已采纳
发布于 2015-12-22 01:58:20
我终于得到了答案。
网络拦截器应如下所示：
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();
}
}那么安装缓存文件就这么简单了
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());Stack Overflow用户
发布于 2015-12-17 10:04:21
在您的CachingControlInterceptor中，您创建了新请求，但从未实际使用过它们。您调用newBuilder并忽略结果，因此实际上永远不会将标头修改发送到任何地方。尝试将这些值赋给request，然后在chain.request()上调用它，而不是在request上调用它。
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 = 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();
}
}Stack Overflow用户
发布于 2016-09-01 22:10:33
您还可以尝试：
public class CachingInterceptor implements Interceptor {
@Override
public okhttp3.Response intercept(Chain chain) throws IOException {
Request request = chain.request();
request = new Request.Builder()
.cacheControl(new CacheControl.Builder()
.maxAge(1, TimeUnit.DAYS)
.minFresh(4, TimeUnit.HOURS)
.maxStale(8, TimeUnit.HOURS)
.build())
.url(request.url())
.build();
return chain.proceed(request);
}
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/34311058
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