blocks|key|2744818|text|2.x版本的编辑：|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|2744819|OkHttp拦截器是脱机时访问缓存的正确方式：|2744820|1)创建Interceptor：|2744821|private+static+final+Interceptor+REWRITE_CACHE_CONTROL_INTERCEPTOR+=+new+Interceptor()+{
++++@Override+public+Response+intercept(Chain+chain)+throws+IOException+{
++++++++Response+originalResponse+=+chain.proceed(chain.request());
++++++++if+(Utils.isNetworkAvailable(context))+{
++++++++++++int+maxAge+=+60;+//+read+from+cache+for+1+minute
++++++++++++return+originalResponse.newBuilder()
++++++++++++++++++++.header("Cache-Control",+"public,+max-age="+%2B+maxAge)
++++++++++++++++++++.build();
++++++++}+else+{
++++++++++++int+maxStale+=+60+*+60+*+24+*+28;+//+tolerate+4-weeks+stale
++++++++++++return+originalResponse.newBuilder()
++++++++++++++++++++.header("Cache-Control",+"public,+only-if-cached,+max-stale="+%2B+maxStale)
++++++++++++++++++++.build();
++++++++}
++++}|code-block|syntax|javascript|2744822|2)设置客户端：|2744823|OkHttpClient+client+=+new+OkHttpClient();
client.networkInterceptors().add(REWRITE_CACHE_CONTROL_INTERCEPTOR);

//setup+cache
File+httpCacheDirectory+=+new+File(context.getCacheDir(),+"responses");
int+cacheSize+=+10+*+1024+*+1024;+//+10+MiB
Cache+cache+=+new+Cache(httpCacheDirectory,+cacheSize);

//add+cache+to+the+client
client.setCache(cache);|2744824|3)添加要改造的客户端|2744825|Retrofit+retrofit+=+new+Retrofit.Builder()
++++++++.baseUrl(BASE_URL)
++++++++.client(client)
++++++++.addConverterFactory(GsonConverterFactory.create())
++++++++.build();|2744826|同时检查@kosiara+-+Bartosz+Kosarzycki的answer，你可能需要从响应中删除一些头部。|2744827|2744828|OKHttp+2.0.x+(检查原始答案)：|2744829|由于OKHttp+2.0.x+HttpResponseCache为Cache，因此setResponseCache为setCache。所以你应该像这样使用setCache：|CODE|2744830|++++++++File+httpCacheDirectory+=+new+File(context.getCacheDir(),+"responses");

++++++++Cache+cache+=+null;
++++++++try+{
++++++++++++cache+=+new+Cache(httpCacheDirectory,+10+*+1024+*+1024);
++++++++}+catch+(IOException+e)+{
++++++++++++Log.e("OKHttp",+"Could+not+create+http+cache",+e);
++++++++}

++++++++OkHttpClient+okHttpClient+=+new+OkHttpClient();
++++++++if+(cache+!=+null)+{
++++++++++++okHttpClient.setCache(cache);
++++++++}
++++++++String+hostURL+=+context.getString(R.string.host_url);

++++++++api+=+new+RestAdapter.Builder()
++++++++++++++++.setEndpoint(hostURL)
++++++++++++++++.setClient(new+OkClient(okHttpClient))
++++++++++++++++.setRequestInterceptor(/*rest+of+the+answer+here+*/)
++++++++++++++++.build()
++++++++++++++++.create(MyApi.class);|2744831|2744832|原始答案：|2744833|事实证明，要使OkClient从缓存中读取，服务器响应必须具有Cache-Control:+public。|2744834|此外，如果您想从网络请求，当可用时，您应该添加Cache-Control:+max-age=0请求头。This+answer展示了如何将其参数化。我是这样使用它的：|2744835|RestAdapter.Builder+builder=+new+RestAdapter.Builder()
+++.setRequestInterceptor(new+RequestInterceptor()+{
++++++++@Override
++++++++public+void+intercept(RequestFacade+request)+{
++++++++++++request.addHeader("Accept",+"application/json;versions=1");
++++++++++++if+(MyApplicationUtils.isNetworkAvailable(context))+{
++++++++++++++++int+maxAge+=+60;+//+read+from+cache+for+1+minute
++++++++++++++++request.addHeader("Cache-Control",+"public,+max-age="+%2B+maxAge);
++++++++++++}+else+{
++++++++++++++++int+maxStale+=+60+*+60+*+24+*+28;+//+tolerate+4-weeks+stale
++++++++++++++++request.addHeader("Cache-Control",+
++++++++++++++++++++"public,+only-if-cached,+max-stale="+%2B+maxStale);
++++++++++++}
++++++++}
});|2744836|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/a/34266019/1120126|1|https://stackoverflow.com/a/20493369/1120126^0|6|3|0|0|0|0|0|0|0|0|4|T|Y|6|0|0|0|0|M|0|F|H|X|5|15|G|1M|8|25|8|0|0|0|0|5|0|7|8|V|L|0|N|O|1F|B|1|0|0^^$0|@$1|2|3|4|5|6|7|1P|8|@$9|1Q|A|1R|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|1S|8|@]|D|@]|E|$]]|$1|H|3|I|5|6|7|1T|8|@]|D|@]|E|$]]|$1|J|3|K|5|L|7|1U|8|@]|D|@]|E|$M|N]]|$1|O|3|P|5|6|7|1V|8|@]|D|@]|E|$]]|$1|Q|3|R|5|L|7|1W|8|@]|D|@]|E|$M|N]]|$1|S|3|T|5|6|7|1X|8|@]|D|@]|E|$]]|$1|U|3|V|5|L|7|1Y|8|@]|D|@]|E|$M|N]]|$1|W|3|X|5|6|7|1Z|8|@$9|20|A|21|B|C]]|D|@$9|22|A|23|1|24]]|E|$]]|$1|Y|3|-4|5|6|7|25|8|@]|D|@]|E|$]]|$1|Z|3|10|5|6|7|26|8|@$9|27|A|28|B|C]]|D|@]|E|$]]|$1|11|3|12|5|6|7|29|8|@$9|2A|A|2B|B|13]|$9|2C|A|2D|B|13]|$9|2E|A|2F|B|13]|$9|2G|A|2H|B|13]|$9|2I|A|2J|B|13]]|D|@]|E|$]]|$1|14|3|15|5|L|7|2K|8|@]|D|@]|E|$M|N]]|$1|16|3|-4|5|6|7|2L|8|@]|D|@]|E|$]]|$1|17|3|18|5|6|7|2M|8|@$9|2N|A|2O|B|C]]|D|@]|E|$]]|$1|19|3|1A|5|6|7|2P|8|@$9|2Q|A|2R|B|13]|$9|2S|A|2T|B|13]]|D|@]|E|$]]|$1|1B|3|1C|5|6|7|2U|8|@$9|2V|A|2W|B|13]]|D|@$9|2X|A|2Y|1|2Z]]|E|$]]|$1|1D|3|1E|5|L|7|30|8|@]|D|@]|E|$M|N]]|$1|1F|3|-4|5|6|7|31|8|@]|D|@]|E|$]]]|1G|$1H|$5|1I|1J|1K|E|$1L|1M]]|1N|$5|1I|1J|1K|E|$1L|1O]]]]

<h2>Edit for Retrofit 2.x:</h2>

OkHttp Interceptor is the right way to access cache when offline: 

1) Create Interceptor:

<pre class="lang-java prettyprint-override"><code>private static final Interceptor REWRITE_CACHE_CONTROL_INTERCEPTOR = new Interceptor() {
 @Override public Response intercept(Chain chain) throws IOException {
 Response originalResponse = chain.proceed(chain.request());
 if (Utils.isNetworkAvailable(context)) {
 int maxAge = 60; // read from cache for 1 minute
 return originalResponse.newBuilder()
 .header("Cache-Control", "public, max-age=" + maxAge)
 .build();
 } else {
 int maxStale = 60 * 60 * 24 * 28; // tolerate 4-weeks stale
 return originalResponse.newBuilder()
 .header("Cache-Control", "public, only-if-cached, max-stale=" + maxStale)
 .build();
 }
 }
</code></pre>

2) Setup client:

<pre class="lang-java prettyprint-override"><code>OkHttpClient client = new OkHttpClient();
client.networkInterceptors().add(REWRITE_CACHE_CONTROL_INTERCEPTOR);

//setup cache
File httpCacheDirectory = new File(context.getCacheDir(), "responses");
int cacheSize = 10 * 1024 * 1024; // 10 MiB
Cache cache = new Cache(httpCacheDirectory, cacheSize);

//add cache to the client
client.setCache(cache);
</code></pre>

3) Add client to retrofit

<pre class="lang-java prettyprint-override"><code>Retrofit retrofit = new Retrofit.Builder()
 .baseUrl(BASE_URL)
 .client(client)
 .addConverterFactory(GsonConverterFactory.create())
 .build();
</code></pre>

Also check @kosiara - Bartosz Kosarzycki's <a href="https://stackoverflow.com/a/34266019/1120126" title="answer">answer</a>. You may need to remove some header from the response.

<hr>

<h2>OKHttp 2.0.x (Check the original answer):</h2>

Since OKHttp 2.0.x <code>HttpResponseCache</code> is <code>Cache</code>, <code>setResponseCache</code> is <code>setCache</code>. So you should <code>setCache</code> like this:

<pre class="lang-java prettyprint-override"><code> File httpCacheDirectory = new File(context.getCacheDir(), "responses");

 Cache cache = null;
 try {
 cache = new Cache(httpCacheDirectory, 10 * 1024 * 1024);
 } catch (IOException e) {
 Log.e("OKHttp", "Could not create http cache", e);
 }

 OkHttpClient okHttpClient = new OkHttpClient();
 if (cache != null) {
 okHttpClient.setCache(cache);
 }
 String hostURL = context.getString(R.string.host_url);

 api = new RestAdapter.Builder()
 .setEndpoint(hostURL)
 .setClient(new OkClient(okHttpClient))
 .setRequestInterceptor(/*rest of the answer here */)
 .build()
 .create(MyApi.class);
</code></pre>

<hr>

<h2>Original Answer:</h2>

It turns out that server response must have <code>Cache-Control: public</code> to make <code>OkClient</code> to read from cache. 

Also If you want to request from network when available, you should add <code>Cache-Control: max-age=0</code> request header. <a href="https://stackoverflow.com/a/20493369/1120126">This answer</a> shows how to do it parameterized. This is how I used it:

<pre class="lang-java prettyprint-override"><code>RestAdapter.Builder builder= new RestAdapter.Builder()
 .setRequestInterceptor(new RequestInterceptor() {
 @Override
 public void intercept(RequestFacade request) {
 request.addHeader("Accept", "application/json;versions=1");
 if (MyApplicationUtils.isNetworkAvailable(context)) {
 int maxAge = 60; // read from cache for 1 minute
 request.addHeader("Cache-Control", "public, max-age=" + maxAge);
 } else {
 int maxStale = 60 * 60 * 24 * 28; // tolerate 4-weeks stale
 request.addHeader("Cache-Control", 
 "public, only-if-cached, max-stale=" + maxStale);
 }
 }
});
</code></pre>

blocks|key|2744843|text|上面所有的方法对我都不起作用。我尝试在+2.0.0-beta2中实现离线缓存。我使用okHttpClient.networkInterceptors()方法添加了一个拦截器，但在尝试脱机使用缓存时收到了java.net.UnknownHostException。事实证明，我还必须添加okHttpClient.interceptors()。|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|CODE|entityRanges|data|2744844|问题是缓存没有写入闪存，因为服务器返回了阻止OkHttp存储响应的Pragma:no-cache。即使在修改请求标头值之后，脱机缓存也不起作用。经过反复试验，我通过从响应中删除杂注而不是从request+-+response.newBuilder().removeHeader("Pragma");中删除杂注，在不修改后端的情况下让缓存正常工作|2744845|升级：2.0.0-beta2；OkHttp：2.5.0|2744846|OkHttpClient+okHttpClient+=+createCachedClient(context);
Retrofit+retrofit+=+new+Retrofit.Builder()
++++++++.client(okHttpClient)
++++++++.baseUrl(API_URL)
++++++++.addConverterFactory(GsonConverterFactory.create())
++++++++.build();
service+=+retrofit.create(RestDataResource.class);|code-block|syntax|javascript|2744847|..。|2744848|private+OkHttpClient+createCachedClient(final+Context+context)+{
++++File+httpCacheDirectory+=+new+File(context.getCacheDir(),+"cache_file");

++++Cache+cache+=+new+Cache(httpCacheDirectory,+20+*+1024+*+1024);
++++OkHttpClient+okHttpClient+=+new+OkHttpClient();
++++okHttpClient.setCache(cache);
++++okHttpClient.interceptors().add(
++++++++++++new+Interceptor()+{
++++++++++++++++@Override
++++++++++++++++public+Response+intercept(Chain+chain)+throws+IOException+{
++++++++++++++++++++Request+originalRequest+=+chain.request();
++++++++++++++++++++String+cacheHeaderValue+=+isOnline(context)+
++++++++++++++++++++++++?+"public,+max-age=2419200"+
++++++++++++++++++++++++:+"public,+only-if-cached,+max-stale=2419200"+;
++++++++++++++++++++Request+request+=+originalRequest.newBuilder().build();
++++++++++++++++++++Response+response+=+chain.proceed(request);
++++++++++++++++++++return+response.newBuilder()
++++++++++++++++++++++++.removeHeader("Pragma")
++++++++++++++++++++++++.removeHeader("Cache-Control")
++++++++++++++++++++++++.header("Cache-Control",+cacheHeaderValue)
++++++++++++++++++++++++.build();
++++++++++++++++}
++++++++++++}
++++);
++++okHttpClient.networkInterceptors().add(
++++++++++++new+Interceptor()+{
++++++++++++++++@Override
++++++++++++++++public+Response+intercept(Chain+chain)+throws+IOException+{
++++++++++++++++++++Request+originalRequest+=+chain.request();
++++++++++++++++++++String+cacheHeaderValue+=+isOnline(context)+
++++++++++++++++++++++++?+"public,+max-age=2419200"+
++++++++++++++++++++++++:+"public,+only-if-cached,+max-stale=2419200"+;
++++++++++++++++++++Request+request+=+originalRequest.newBuilder().build();
++++++++++++++++++++Response+response+=+chain.proceed(request);
++++++++++++++++++++return+response.newBuilder()
++++++++++++++++++++++++.removeHeader("Pragma")
++++++++++++++++++++++++.removeHeader("Cache-Control")
++++++++++++++++++++++++.header("Cache-Control",+cacheHeaderValue)
++++++++++++++++++++++++.build();
++++++++++++++++}
++++++++++++}
++++);
++++return+okHttpClient;
}|2744849|2744850|public+interface+RestDataResource+{

++++@GET("rest-data")+
++++Call<List<RestItem>>+getRestData();

}|2744851|entityMap^0|J|C|16|Y|2T|T|3Y|R|0|X|F|2W|19|0|3|B|M|5|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@$9|Z|A|10|B|C]|$9|11|A|12|B|D]|$9|13|A|14|B|D]|$9|15|A|16|B|D]]|E|@]|F|$]]|$1|G|3|H|5|6|7|17|8|@$9|18|A|19|B|D]|$9|1A|A|1B|B|D]]|E|@]|F|$]]|$1|I|3|J|5|6|7|1C|8|@$9|1D|A|1E|B|C]|$9|1F|A|1G|B|C]]|E|@]|F|$]]|$1|K|3|L|5|M|7|1H|8|@]|E|@]|F|$N|O]]|$1|P|3|Q|5|6|7|1I|8|@]|E|@]|F|$]]|$1|R|3|S|5|M|7|1J|8|@]|E|@]|F|$N|O]]|$1|T|3|Q|5|6|7|1K|8|@]|E|@]|F|$]]|$1|U|3|V|5|M|7|1L|8|@]|E|@]|F|$N|O]]|$1|W|3|-4|5|6|7|1M|8|@]|E|@]|F|$]]]|X|$]]

All of the anwsers above did not work for me. I tried to implement offline cache in retrofit 2.0.0-beta2. I added an interceptor using <code>okHttpClient.networkInterceptors()</code> method but received <code>java.net.UnknownHostException</code> when I tried to use the cache offline. It turned out that I had to add <code>okHttpClient.interceptors()</code> as well.

The problem was that cache wasn't written to flash storage because the server returned <code>Pragma:no-cache</code> which prevents OkHttp from storing the response. Offline cache didn't work even after modifying request header values. After some trial-and-error I got the cache to work without modifying the backend side by removing pragma from reponse instead of the request - <code>response.newBuilder().removeHeader("Pragma");</code>

Retrofit: 2.0.0-beta2; OkHttp: 2.5.0

<pre><code>OkHttpClient okHttpClient = createCachedClient(context);
Retrofit retrofit = new Retrofit.Builder()
 .client(okHttpClient)
 .baseUrl(API_URL)
 .addConverterFactory(GsonConverterFactory.create())
 .build();
service = retrofit.create(RestDataResource.class);
</code></pre>

...

<pre><code>private OkHttpClient createCachedClient(final Context context) {
 File httpCacheDirectory = new File(context.getCacheDir(), "cache_file");

 Cache cache = new Cache(httpCacheDirectory, 20 * 1024 * 1024);
 OkHttpClient okHttpClient = new OkHttpClient();
 okHttpClient.setCache(cache);
 okHttpClient.interceptors().add(
 new Interceptor() {
 @Override
 public Response intercept(Chain chain) throws IOException {
 Request originalRequest = chain.request();
 String cacheHeaderValue = isOnline(context) 
 ? "public, max-age=2419200" 
 : "public, only-if-cached, max-stale=2419200" ;
 Request request = originalRequest.newBuilder().build();
 Response response = chain.proceed(request);
 return response.newBuilder()
 .removeHeader("Pragma")
 .removeHeader("Cache-Control")
 .header("Cache-Control", cacheHeaderValue)
 .build();
 }
 }
 );
 okHttpClient.networkInterceptors().add(
 new Interceptor() {
 @Override
 public Response intercept(Chain chain) throws IOException {
 Request originalRequest = chain.request();
 String cacheHeaderValue = isOnline(context) 
 ? "public, max-age=2419200" 
 : "public, only-if-cached, max-stale=2419200" ;
 Request request = originalRequest.newBuilder().build();
 Response response = chain.proceed(request);
 return response.newBuilder()
 .removeHeader("Pragma")
 .removeHeader("Cache-Control")
 .header("Cache-Control", cacheHeaderValue)
 .build();
 }
 }
 );
 return okHttpClient;
}
</code></pre>

...

<pre><code>public interface RestDataResource {

 @GET("rest-data") 
 Call&lt;List&lt;RestItem&gt;&gt; getRestData();

}
</code></pre>

blocks|key|158941|text|在@kosiara-bartosz-kasarzycki的answer的基础上，我创建了一个示例项目，该项目使用retrofit、okhttp、rxjava和guava从内存->磁盘->网络中正确加载。https://github.com/digitalbuddha/StoreDemo|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|158942|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/a/34266019/1235698|1|https://github.com/digitalbuddha/StoreDemo^0|T|6|0|2T|16|1|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@$A|O|B|P|1|Q]|$A|R|B|S|1|T]]|C|$]]|$1|D|3|-4|5|6|7|U|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]|L|$5|G|H|I|C|$J|M]]]]

building on @kosiara-bartosz-kasarzycki's <a href="https://stackoverflow.com/a/34266019/1235698">answer</a>, I created a sample project that properly loads from memory->disk->network using retrofit, okhttp, rxjava and guava.
<a href="https://github.com/digitalbuddha/StoreDemo" rel="nofollow noreferrer">https://github.com/digitalbuddha/StoreDemo</a>

blocks|key|2744860|text|我的解决方案是：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2744861|private+BackendService()+{

++++httpCacheDirectory+=+new+File(context.getCacheDir(),++"responses");
++++int+cacheSize+=+10+*+1024+*+1024;+//+10+MiB
++++Cache+cache+=+new+Cache(httpCacheDirectory,+cacheSize);

++++httpClient+=+new+OkHttpClient.Builder()
++++++++++++.addNetworkInterceptor(REWRITE_RESPONSE_INTERCEPTOR)
++++++++++++.addInterceptor(OFFLINE_INTERCEPTOR)
++++++++++++.cache(cache)
++++++++++++.build();

++++Retrofit+retrofit+=+new+Retrofit.Builder()
++++++++++++.baseUrl("https://api.backend.com")
++++++++++++.client(httpClient)
++++++++++++.addConverterFactory(GsonConverterFactory.create())
++++++++++++.build();

++++backendApi+=+retrofit.create(BackendApi.class);
}

private+static+final+Interceptor+REWRITE_RESPONSE_INTERCEPTOR+=+chain+->+{
++++Response+originalResponse+=+chain.proceed(chain.request());
++++String+cacheControl+=+originalResponse.header("Cache-Control");

++++if+(cacheControl+==+null+%7C%7C+cacheControl.contains("no-store")+%7C%7C+cacheControl.contains("no-cache")+%7C%7C
++++++++++++cacheControl.contains("must-revalidate")+%7C%7C+cacheControl.contains("max-age=0"))+{
++++++++return+originalResponse.newBuilder()
++++++++++++++++.header("Cache-Control",+"public,+max-age="+%2B+10)
++++++++++++++++.build();
++++}+else+{
++++++++return+originalResponse;
++++}
};

private+static+final+Interceptor+OFFLINE_INTERCEPTOR+=+chain+->+{
++++Request+request+=+chain.request();

++++if+(!isOnline())+{
++++++++Log.d(TAG,+"rewriting+request");

++++++++int+maxStale+=+60+*+60+*+24+*+28;+//+tolerate+4-weeks+stale
++++++++request+=+request.newBuilder()
++++++++++++++++.header("Cache-Control",+"public,+only-if-cached,+max-stale="+%2B+maxStale)
++++++++++++++++.build();
++++}

++++return+chain.proceed(request);
};

public+static+boolean+isOnline()+{
++++ConnectivityManager+cm+=+(ConnectivityManager)+MyApplication.getApplication().getSystemService(Context.CONNECTIVITY_SERVICE);
++++NetworkInfo+netInfo+=+cm.getActiveNetworkInfo();
++++return+netInfo+!=+null+&&+netInfo.isConnectedOrConnecting();
}|code-block|syntax|javascript|2744862|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

My solution:

<pre><code>private BackendService() {

 httpCacheDirectory = new File(context.getCacheDir(), "responses");
 int cacheSize = 10 * 1024 * 1024; // 10 MiB
 Cache cache = new Cache(httpCacheDirectory, cacheSize);

 httpClient = new OkHttpClient.Builder()
 .addNetworkInterceptor(REWRITE_RESPONSE_INTERCEPTOR)
 .addInterceptor(OFFLINE_INTERCEPTOR)
 .cache(cache)
 .build();

 Retrofit retrofit = new Retrofit.Builder()
 .baseUrl("https://api.backend.com")
 .client(httpClient)
 .addConverterFactory(GsonConverterFactory.create())
 .build();

 backendApi = retrofit.create(BackendApi.class);
}

private static final Interceptor REWRITE_RESPONSE_INTERCEPTOR = chain -&gt; {
 Response originalResponse = chain.proceed(chain.request());
 String cacheControl = originalResponse.header("Cache-Control");

 if (cacheControl == null || cacheControl.contains("no-store") || cacheControl.contains("no-cache") ||
 cacheControl.contains("must-revalidate") || cacheControl.contains("max-age=0")) {
 return originalResponse.newBuilder()
 .header("Cache-Control", "public, max-age=" + 10)
 .build();
 } else {
 return originalResponse;
 }
};

private static final Interceptor OFFLINE_INTERCEPTOR = chain -&gt; {
 Request request = chain.request();

 if (!isOnline()) {
 Log.d(TAG, "rewriting request");

 int maxStale = 60 * 60 * 24 * 28; // tolerate 4-weeks stale
 request = request.newBuilder()
 .header("Cache-Control", "public, only-if-cached, max-stale=" + maxStale)
 .build();
 }

 return chain.proceed(request);
};

public static boolean isOnline() {
 ConnectivityManager cm = (ConnectivityManager) MyApplication.getApplication().getSystemService(Context.CONNECTIVITY_SERVICE);
 NetworkInfo netInfo = cm.getActiveNetworkInfo();
 return netInfo != null &amp;&amp; netInfo.isConnectedOrConnecting();
}
</code></pre>

blocks|key|156466|text|使用Retrofit2和OkHTTP3进行缓存：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|156467|OkHttpClient+client+=+new+OkHttpClient
++.Builder()
++.cache(new+Cache(App.sApp.getCacheDir(),+10+*+1024+*+1024))+//+10+MB
++.addInterceptor(new+Interceptor()+{
++++@Override+public+Response+intercept(Chain+chain)+throws+IOException+{
++++++Request+request+=+chain.request();
++++++if+(NetworkUtils.isNetworkAvailable())+{
++++++++request+=+request.newBuilder().header("Cache-Control",+"public,+max-age="+%2B+60).build();
++++++}+else+{
++++++++request+=+request.newBuilder().header("Cache-Control",+"public,+only-if-cached,+max-stale="+%2B+60+*+60+*+24+*+7).build();
++++++}
++++++return+chain.proceed(request);
++++}
++})
++.build();|code-block|syntax|javascript|156468|NetworkUtils.isNetworkAvailable()静态方法：|156469|public+static+boolean+isNetworkAvailable(Context+context)+{
++++++++ConnectivityManager+cm+=
++++++++++++++++(ConnectivityManager)+context.getSystemService(Context.CONNECTIVITY_SERVICE);
++++++++NetworkInfo+activeNetwork+=+cm.getActiveNetworkInfo();
++++++++return+activeNetwork+!=+null+&&
++++++++++++++++activeNetwork.isConnectedOrConnecting();
++++}|156470|然后只需将客户端添加到改进的构建器中：|156471|Retrofit+retrofit+=+new+Retrofit.Builder()
++++++++++++++++++++.baseUrl(BASE_URL)
++++++++++++++++++++.client(client)
++++++++++++++++++++.addConverterFactory(GsonConverterFactory.create())
++++++++++++++++++++.build();|156472|原文来源：https://newfivefour.com/android-retrofit2-okhttp3-cache-network-request-offline.html|offset|length|156473|entityMap|0|LINK|mutability|MUTABLE|url|https://newfivefour.com/android-retrofit2-okhttp3-cache-network-request-offline.html^0|0|0|0|0|0|0|5|2C|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|11|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|12|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|13|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|14|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|15|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|16|8|@]|9|@$Q|17|R|18|1|19]]|A|$]]|$1|S|3|-4|5|6|7|1A|8|@]|9|@]|A|$]]]|T|$U|$5|V|W|X|A|$Y|Z]]]]

Cache with Retrofit2 and OkHTTP3:

<pre><code>OkHttpClient client = new OkHttpClient
 .Builder()
 .cache(new Cache(App.sApp.getCacheDir(), 10 * 1024 * 1024)) // 10 MB
 .addInterceptor(new Interceptor() {
 @Override public Response intercept(Chain chain) throws IOException {
 Request request = chain.request();
 if (NetworkUtils.isNetworkAvailable()) {
 request = request.newBuilder().header("Cache-Control", "public, max-age=" + 60).build();
 } else {
 request = request.newBuilder().header("Cache-Control", "public, only-if-cached, max-stale=" + 60 * 60 * 24 * 7).build();
 }
 return chain.proceed(request);
 }
 })
 .build();
</code></pre>

NetworkUtils.isNetworkAvailable() static method:

<pre><code>public static boolean isNetworkAvailable(Context context) {
 ConnectivityManager cm =
 (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
 NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
 return activeNetwork != null &amp;&amp;
 activeNetwork.isConnectedOrConnecting();
 }
</code></pre>

Then just add client to the retrofit builder:

<pre><code>Retrofit retrofit = new Retrofit.Builder()
 .baseUrl(BASE_URL)
 .client(client)
 .addConverterFactory(GsonConverterFactory.create())
 .build();
</code></pre>

Original source: <a href="https://newfivefour.com/android-retrofit2-okhttp3-cache-network-request-offline.html" rel="nofollow">https://newfivefour.com/android-retrofit2-okhttp3-cache-network-request-offline.html</a>

blocks|key|155308|text|答案是肯定的，基于上面的回答，我开始编写单元测试来验证所有可能的用例：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|155309|155310|Use缓存当offline|unordered-list-item|offset|length|style|BOLD|155311|Use缓存响应时首先缓存响应，直到过期，然后使用网络|155312|先使用网络，然后对某些请求进行缓存对于某些响应，|155313|不会存储在缓存中|155314|155315|我构建了一个小的助手库来轻松地配置OKHttp缓存，你可以在Github上看到相关的单元测试：https://github.com/ncornette/OkCacheControl/blob/master/okcache-control/src/test/java/com/ncornette/cache/OkCacheControlTest.java|155316|一个Unittest，用于演示离线时缓存的使用：|155317|@Test
public+void+test_USE_CACHE_WHEN_OFFLINE()+throws+Exception+{
++++//given
++++givenResponseInCache("Expired+Response+in+cache",+-5,+MINUTES);
++++given(networkMonitor.isOnline()).willReturn(false);

++++//when
++++//This+response+is+only+used+to+not+block+when+test+fails
++++mockWebServer.enqueue(new+MockResponse().setResponseCode(404));
++++Response+response+=+getResponse();

++++//then
++++then(response.body().string()).isEqualTo("Expired+Response+in+cache");
++++then(cache.hitCount()).isEqualTo(1);
}|code-block|syntax|javascript|155318|如您所见，即使缓存已过期，也可以使用它。希望这能有所帮助。|155319|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/ncornette/OkCacheControl/blob/master/okcache-control/src/test/java/com/ncornette/cache/OkCacheControlTest.java^0|0|0|0|D|0|0|0|0|0|1B|3L|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|19|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|1A|8|@]|9|@]|A|$]]|$1|C|3|D|5|E|7|1B|8|@$F|1C|G|1D|H|I]]|9|@]|A|$]]|$1|J|3|K|5|E|7|1E|8|@]|9|@]|A|$]]|$1|L|3|M|5|E|7|1F|8|@]|9|@]|A|$]]|$1|N|3|O|5|E|7|1G|8|@]|9|@]|A|$]]|$1|P|3|-4|5|6|7|1H|8|@]|9|@]|A|$]]|$1|Q|3|R|5|6|7|1I|8|@]|9|@$F|1J|G|1K|1|1L]]|A|$]]|$1|S|3|T|5|6|7|1M|8|@]|9|@]|A|$]]|$1|U|3|V|5|W|7|1N|8|@]|9|@]|A|$X|Y]]|$1|Z|3|10|5|6|7|1O|8|@]|9|@]|A|$]]|$1|11|3|-4|5|6|7|1P|8|@]|9|@]|A|$]]]|12|$13|$5|14|15|16|A|$17|18]]]]

The answer is YES, based on the above answers, I started writing unit tests to verify all possible use cases : 

<ul>
<li>Use cache when offline</li>
<li>Use cached response first until expired, then network</li>
<li>Use network first then cache for some requests</li>
<li>Do not store in cache for some responses</li>
</ul>

I built a small helper lib to configure OKHttp cache easily, you can see the related unittest here on Github : <a href="https://github.com/ncornette/OkCacheControl/blob/master/okcache-control/src/test/java/com/ncornette/cache/OkCacheControlTest.java" rel="noreferrer">https://github.com/ncornette/OkCacheControl/blob/master/okcache-control/src/test/java/com/ncornette/cache/OkCacheControlTest.java</a>

Unittest that demonstrates the use of cache when offline : 

<pre><code>@Test
public void test_USE_CACHE_WHEN_OFFLINE() throws Exception {
 //given
 givenResponseInCache("Expired Response in cache", -5, MINUTES);
 given(networkMonitor.isOnline()).willReturn(false);

 //when
 //This response is only used to not block when test fails
 mockWebServer.enqueue(new MockResponse().setResponseCode(404));
 Response response = getResponse();

 //then
 then(response.body().string()).isEqualTo("Expired Response in cache");
 then(cache.hitCount()).isEqualTo(1);
}
</code></pre>

As you can see, cache can be used even if it has expired.
Hope it will help.

blocks|key|2744972|text|注意！缓存中内置的OkHttp只适用于GET方法(请参考上面的解决方案)。如果你想缓存POST请求，你必须自己实现。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2744973|📷|atomic|2744974|​|2744975|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/f2a08759e9d9d76c7a02e0c769c169a7.png|imageAlt^0|J|3|17|4|0|0|1|0|0|0^^$0|@$1|2|3|4|5|6|7|T|8|@$9|U|A|V|B|C]|$9|W|A|X|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|Y|8|@]|D|@$9|Z|A|10|1|11]]|E|$]]|$1|I|3|J|5|6|7|12|8|@]|D|@]|E|$]]|$1|K|3|-4|5|6|7|13|8|@]|D|@]|E|$]]]|L|$M|$5|N|O|P|E|$Q|R|S|-4]]]]

Attention! OkHttp build in cache only work for <code>GET</code> method(refer to above solution). If you want to cache <code>POST</code> request, you must implement yourself.
<a href="https://i.stack.imgur.com/YKIdw.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/YKIdw.png" alt="enter image description here" /></a>

I'm trying to use Retrofit &amp; OKHttp to cache HTTP responses. I followed <a href="https://gist.github.com/swankjesse/5889518" rel="noreferrer" title="gist">this gist</a> and, ended up with this code:

<pre class="lang-java prettyprint-override"><code>File httpCacheDirectory = new File(context.getCacheDir(), "responses");

HttpResponseCache httpResponseCache = null;
try {
 httpResponseCache = new HttpResponseCache(httpCacheDirectory, 10 * 1024 * 1024);
} catch (IOException e) {
 Log.e("Retrofit", "Could not create http cache", e);
}

OkHttpClient okHttpClient = new OkHttpClient();
okHttpClient.setResponseCache(httpResponseCache);

api = new RestAdapter.Builder()
 .setEndpoint(API_URL)
 .setLogLevel(RestAdapter.LogLevel.FULL)
 .setClient(new OkClient(okHttpClient))
 .build()
 .create(MyApi.class);
</code></pre>

And this is MyApi with the Cache-Control headers


<pre><code>public interface MyApi {
 @Headers("Cache-Control: public, max-age=640000, s-maxage=640000 , max-stale=2419200")
 @GET("/api/v1/person/1/")
 void requestPerson(
 Callback&lt;Person&gt; callback
 );
</code></pre>

First I request online and check the cache files. The correct JSON response and headers are there. But when I try to request offline, I always get <code>RetrofitError UnknownHostException</code>. Is there anything else I should do to make Retrofit read the response from cache?

EDIT:
Since OKHttp 2.0.x <code>HttpResponseCache</code> is <code>Cache</code>, <code>setResponseCache</code> is <code>setCache</code>

Can Retrofit with OKHttp use cache data when offline

单元测试

服务器

JSON

我正在尝试使用Retrofit & OKHttp来缓存HTTP响应。我关注了，最后得到了下面的代码：File httpCacheDirectory = new File(context.getCacheDir(), "responses");HttpResponseCache httpResponseCache = n...

问离线时是否可以使用缓存数据通过OKHttp进行改造
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