I'm trying to cache response via OkHttp and Retrofit. I understand there are several questions similar to mine but none of those are able to address my issue.
Following is my Interceptor responsible for modifying the headers.
private static class CachingControlInterceptor implements Interceptor {
#Override
public Response intercept(Chain chain) throws IOException {
Request request = chain.request();
Response originalResponse = chain.proceed(request);
return originalResponse.newBuilder()
.header("Cache-Control", (UtilityMethods.isNetworkAvailable()) ?
"public, max-age=60" : "public, max-stale=604800")
.build();
}
}
Now, this works perfectly in the first case -
Internet connection is available.
A valid response is received and cached.
Disconnect the device from the internet.
Send the same request as previous one within a minute -> Response is same as last
Next, send the same request after a minute is complete -> No response (UnknownHostException)
This makes the first part ("public, max-age=60") complete.
But, somehow, "public, max-age=60" part does not work at all.
This part should enable okhttp to fetch the a week old stale data when the device is offline but instead, I get UnknownHostException.
I think this is what you are looking for :
.header("Cache-Control", (UtilityMethods.isNetworkAvailable()) ?
"public, max-age=60" : "public, only-if-cached, max-stale=604800")
This adds the only-if-cached directive for when the network is unavailable. This only accepts the response if it is in the cache.
Related
I read dozens of tutorial and Stackoverflow answers to my problem but nothing is working for me! Also, most of them are old so probably OKHTTP changed somehow.
All I want is to enable offline caching for Retrofit.
I am using GET
I tried using only offlineCacheInterceptor as an Interceptor, but I kept getting:
Unable to resolve host "jsonplaceholder.typicode.com": No address associated with hostname
I tried using a combination of offlineCacheInterceptoras an Interceptor + provideCacheInterceptor() as a NetworkInterceptor, but I kept getting:
504 Unsatisfiable Request (only-if-cached) and a null response.body()
I even made sure to add .removeHeader("Pragma") everywhere!
I tried all these Links:
https://newfivefour.com/android-retrofit2-okhttp3-cache-network-request-offline.html (One interceptor, Not working!!)
https://medium.com/mindorks/caching-with-retrofit-store-responses-offline-71439ed32fda (One interceptor, Not working!)
https://caster.io/lessons/retrofit-2-offline-cache (Separate Online + Offline caching, Not working)
https://www.journaldev.com/23297/android-retrofit-okhttp-offline-caching (Not working, 504 Unsatisfiable Request (only-if-cached))
http://mikescamell.com/gotcha-when-offline-caching-with-okhttp3/ (One interceptor, Not working!!)
https://stackoverflow.com/a/48295397/8086424 (Not Working)
Unable to resolve host "jsonplaceholder.typicode.com": No address associated with hostname
Can Retrofit with OKHttp use cache data when offline (TOO confusing!)
Here's my code:
public static Retrofit getRetrofitInstance(Context context) {
if (retrofit == null) {
c = context;
int cacheSize = 10 * 1024 * 1024; // 10 MB
Cache cache = new Cache(context.getCacheDir(), cacheSize);
OkHttpClient okHttpClient = new OkHttpClient.Builder()
.addInterceptor(provideHttpLoggingInterceptor())
.addInterceptor(offlineCacheInterceptor)
.addNetworkInterceptor(provideCacheInterceptor())
.cache(cache)
.build();
//////////////////////////
retrofit = new retrofit2.Retrofit.Builder()
.baseUrl(BASE_URL)
.addConverterFactory(GsonConverterFactory.create())
.client(okHttpClient)
.build();
}
return retrofit;
}
public static Interceptor offlineCacheInterceptor = new Interceptor() {
#Override
public Response intercept(Chain chain) throws IOException {
Request request = chain.request();
Log.e("bbbb", "bbbb");
if (!checkInternetAvailability()) {
Log.e("aaaaa", "aaaaaa");
CacheControl cacheControl = new CacheControl.Builder()
.maxStale(30, TimeUnit.DAYS)
.build();
request = request.newBuilder()
.cacheControl(cacheControl)
.removeHeader("Pragma")
.build();
}
return chain.proceed(request);
}
};
public static Interceptor provideCacheInterceptor() {
return new Interceptor() {
#Override
public Response intercept(Chain chain) throws IOException {
Response response = chain.proceed(chain.request());
// re-write response header to force use of cache
CacheControl cacheControl = new CacheControl.Builder()
.maxAge(2, TimeUnit.MINUTES)
.build();
return response.newBuilder()
.header(CACHE_CONTROL, cacheControl.toString())
.removeHeader("Pragma")
.build();
}
};
}
I am using jsonplaceholder.typicode.com/photos that returns:
content-type: application/json; charset=utf-8
date: Sun, 21 Oct 2018 14:26:41 GMT
set-cookie: __cfduid=d9e935012d2f789245b1e2599a41e47511540132001; expires=Mon, 21-Oct-19 14:26:41 GMT; path=/; domain=.typicode.com; HttpOnly
x-powered-by: Express
vary: Origin, Accept-Encoding
access-control-allow-credentials: true
expires: Sun, 21 Oct 2018 18:26:41 GMT
x-content-type-options: nosniff
etag: W/"105970-HCYFejK2YCxztz8++2rHnutkPOQ"
via: 1.1 vegur
cf-cache-status: REVALIDATED
expect-ct: max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct"
server: cloudflare
cf-ray: 46d466910cab3d77-MXP
Cache-Control: public, max-age=60
June 2021 (Retrofit 2.9.0 or OKHTTP 3.14.9) Complete Solution (Update)
Same approach is still working since: Oct. 2018
Oct. 2018 (Retrofit 2.4 or OKHTTP 3.11) Complete Solution
Ok, so Online & Offline caching using OKHTTP or Retrofit has been causing so many problems for many people on stackoverflow and other forums. There are tons of misleading information and non-working code samples all over the internet.
So, today I will explain how you can implement online & offline caching using Retrofit & OKHTTP with clear steps + How to test and know whether you are getting the data from cache or network.
If you are getting a 504 Unsatisfiable Request (only-if-cached) OR an Unable to resolve host "HOST": No address associated with hostnamethen you can use any of the following solutions.
Before you begin, you must always remember to:
Make sure you are using a GET request and not a POST!
Always make sure you add .removeHeader("Pragma") as shown below (This lets you override the server's caching protocol)
Avoid using the HttpLoggingInterceptor while testing, it can cause some confusion in the beginning. Enable it in the end if you want.
ALWAYS ALWAYS ALWAYS delete your app from the device and reinstall it again upon every change in code, if you want to explore using Interceptors. Otherwise changing code while the old cache data is still on the device will cause you lots of confusion and misleading deductions!
The order of adding Interceptors to OKHTTPClient object matters!
N.B: If you want to depend on your server's caching protocol for online and offline caching, then don't read the 2 solutions. Just read this article. All you need is to create a cache object and attache it to OKHTTPClient object.
Solution 1: (Longer, but you have full control)
Step 1: (Create onlineInterceptor)
static Interceptor onlineInterceptor = new Interceptor() {
#Override
public okhttp3.Response intercept(Chain chain) throws IOException {
okhttp3.Response response = chain.proceed(chain.request());
int maxAge = 60; // read from cache for 60 seconds even if there is internet connection
return response.newBuilder()
.header("Cache-Control", "public, max-age=" + maxAge)
.removeHeader("Pragma")
.build();
}
};
Step 2: (Create Offline Interceptor) (Only if you want cache access when offline)
static Interceptor offlineInterceptor= new Interceptor() {
#Override
public okhttp3.Response intercept(Chain chain) throws IOException {
Request request = chain.request();
if (!isInternetAvailable()) {
int maxStale = 60 * 60 * 24 * 30; // Offline cache available for 30 days
request = request.newBuilder()
.header("Cache-Control", "public, only-if-cached, max-stale=" + maxStale)
.removeHeader("Pragma")
.build();
}
return chain.proceed(request);
}
};
Step 3: (Create a cache object)
int cacheSize = 10 * 1024 * 1024; // 10 MB
Cache cache = new Cache(context.getCacheDir(), cacheSize);
Step 4: (Add interceptors and cache to an OKHTTPClient object)
OkHttpClient okHttpClient = new OkHttpClient.Builder()
// .addInterceptor(provideHttpLoggingInterceptor()) // For HTTP request & Response data logging
.addInterceptor(OFFLINE_INTERCEPTOR)
.addNetworkInterceptor(ONLINE_INTERCEPTOR)
.cache(cache)
.build();
Step 5:(If you are using Retrofit, add the OKHTTPClient object to it)
retrofit = new retrofit2.Retrofit.Builder()
.baseUrl(BASE_URL)
.addConverterFactory(GsonConverterFactory.create())
.client(okHttpClient)
.build();
DONE!
Solution 2: (Just use a library to do all that for you! But deal with the limitations)
Use OkCacheControl library
Step 1 (Create Cache object as shown above)
Step 2 (Create an OKHTTPClient object)
OkHttpClient okHttpClient = OkCacheControl.on(new OkHttpClient.Builder())
.overrideServerCachePolicy(1, MINUTES)
.forceCacheWhenOffline(networkMonitor)
.apply() // return to the OkHttpClient.Builder instance
//.addInterceptor(provideHttpLoggingInterceptor())
.cache(cache)
.build();
Step 3:(Attach the OKHTTPClient object to Retrofit as shown above)
Step 4: (Create a NetworkMonitor Object)
static OkCacheControl.NetworkMonitor networkMonitor=new
OkCacheControl.NetworkMonitor() {
#Override
public boolean isOnline() {
return isInternetAvailable();
}
};
DONE!
Testing:
In order to know whether your device is getting data from the network or from cache, simply add the following code to your onResponse method of Retrofit.
public void onResponse(Call<List<RetroPhoto>> call, Response<List<RetroPhoto>> response) {
if (response.raw().cacheResponse() != null) {
Log.e("Network", "response came from cache");
}
if (response.raw().networkResponse() != null) {
Log.e("Network", "response came from server");
}
}
If the device is using the Network, you will get "response came from server".
If device is using Cache, you will get both of the above responses! For more info about this read this article.
For more info about using OKHTTP interceptors go to this page.
I'm using Retrofit2 to make requests to server.
The problem is: sometimes the server will return code 401 for every request from an user. If the user get this code, he should be immediately kicked out from the app (logged out and not be able to do anything before re-login).
So for every request that being sent to the server, I want to check if the server response this code. It's not beautiful writing this check in all the request calls, so I want to write this check only one and it will perform every time user makes request!
Retrofit (current release) needs an HTTP client to make requests. OkHttp library by same developer comes bundled with Retrofit as default client. OkHttp supports adding Interceptor's to the client which can intercept request execution.
For Example:
import android.util.Log;
import java.io.IOException;
import okhttp3.Interceptor;
import okhttp3.Request;
import okhttp3.Response;
public class ErrorInterceptor implements Interceptor {
#Override
public Response intercept(Chain chain) throws IOException {
// before request
Request request = chain.request();
// execute request
Response response = chain.proceed(request);
// after request
// inspect status codes of unsuccessful responses
switch (response.code()){
case 401:
// do something else
Log.e("TEST","Unauthorized error for: " +request.url());
// perhaps throw a custom exception ?
throw new IOException("Unauthorized !!");
}
return response;
}
}
To use it, include it in OkHttpClient that Retrofit instance uses:
OkHttpClient client = new OkHttpClient.Builder()
.addInterceptor(new ErrorInterceptor())
.build();
Retrofit retrofit = new Retrofit.Builder()
.client(client)
.baseUrl("/")
.build();
So, you can implement an Interceptor for each "global logic" or "cross-cutting concern" and add them all in a sequence to Retrofit.
If you need check "401" code there is special object in OkHttp for it: Authenticator (Recipes in OkHttp). For example:
public class RefreshTokenAuthenticator implements Authenticator {
#Override
public Request authenticate(Route route, Response response) throws IOException {
// You get here, if response code was 401.
// Then you can somehow change your request or data in your app in this method and resend your request.
Request request = response.request();
HttpUrl url = request.url().newBuilder()
.setQueryParameter("access_token", "new_access_token_may_be")
.build();
request = request.newBuilder()
.url(url)
.build();
return request;
}
}
I have seen good long discussion on this topic and it is claimed to be fixed in 2.3.0.
Here is the combination I am using
compile 'com.squareup.retrofit2:retrofit:2.0.0-beta4'
compile 'com.squareup.retrofit2:converter-gson:2.0.0-beta4'
compile 'com.squareup.okhttp3:logging-interceptor:3.0.1'
compile 'com.squareup.okhttp3:okhttp:3.2.0'
logs I see against received response, have Etag; but subsequent request I do doesn't have If-None-Match passed in its header.
I tested it by inserting If-None-Match explicitly by my code, caching worked and response was expected one. So there is surely something wrong with version of libraries I am using or something not good about my code.
Here I am setting up okClient.
HttpLoggingInterceptor httpLoggingInterceptor = new HttpLoggingInterceptor();
httpLoggingInterceptor.setLevel(HttpLoggingInterceptor.Level.HEADERS);
okhttp3.OkHttpClient okClient = new okhttp3.OkHttpClient.Builder()
.addInterceptor(new HeaderInterceptor())
.addInterceptor(httpLoggingInterceptor)
.cache(createCacheForOkHTTP())
.connectTimeout(5, TimeUnit.MINUTES)
.readTimeout(5, TimeUnit.MINUTES)
.build();
retrofit = new Retrofit.Builder()
.baseUrl(AppConfig.API_URL)
.addConverterFactory(GsonConverterFactory.create())
.client(okClient)
.build();
My header interceptor contains the logic that is pretty much focused to my API itself. Here it is
private class HeaderInterceptor
implements Interceptor {
private String generateAuthHeader(AuthResponse accessToken) {
if (accessToken == null) {
return "";
}
return String.format("Bearer %s", accessToken.getAccessToken());
}
#Override
public okhttp3.Response intercept(Chain chain)
throws IOException {
Request request = chain.request();
final String authorizationValue = generateAuthHeader(runtime.getPrefAccessToken());
if (!TextUtils.isEmpty(authorizationValue)) {
request = request.newBuilder()
.addHeader(AppConfig.API_KEY_AUTHORIZATION, authorizationValue)
.addHeader(AppConfig.API_KEY_ACCEPT, AppConfig.API_ACCEPT)
.build();
//.addHeader("If-None-Match", "a69385c6d34596e48cdddd3ce475d290")
} else {
request = request.newBuilder()
.addHeader(AppConfig.API_KEY_CONTENT_TYPE, AppConfig.API_CONTENT_TYPE)
.addHeader(AppConfig.API_KEY_ACCEPT, AppConfig.API_ACCEPT)
.build();
}
okhttp3.Response response = chain.proceed(request);
return response;
}
}
And here is the method using which I am setting up cache.
private Cache createCacheForOkHTTP() {
Cache cache = null;
cache = new Cache(App.getInstance().getBaseContext().getCacheDir(), 1024 * 1024 * 10);
return cache;
}
Looking for some quick and effective response as I already have spent reasonable time finding the solution but no luck.
Thanks
Your code seems to be working, I haven't tried it out but i faced the same issue few weeks ago. It turned out that it was because of the log from retrofit did not show the if-none-match header. But when i tried to intercept the request using proxy and redirect the request to my laptop first (i was using mitmproxy app), the if-none-match header appeared.
Anyway, if you look into /okhttp3/internal/http/CacheStrategy.java inside this method private CacheStrategy getCandidate(), you will see that OkHttp3 is actually using the etag & if-none-match header properly.
Hope this clarifies.
I am caching http response using okHttp, I didn't implemented anything in server side. so for caching I am using Interceptor. and I have set cache age to one week. so it works fine for one week, If I have changed the device time to more than one week then it is loads from the server and it is not taking from cache, what I need is after expiring the age it should take the new response from server and it should persist until expiring the cache. my Interceptor is given below.
private class CacheInterceptor implements Interceptor {
Context mContext;
public CacheInterceptor(Context context) {
this.mContext = context;
}
#Override
public Response intercept(Chain chain) throws IOException {
Request request = chain.request();
request = request.newBuilder()
.header(HEADER_SESSION_ID, sessionId)
.header(HEADER_MOBILE_OS, Constants.MOBILE_OS)
.build();
}
Response response = chain.proceed(request);
return response.newBuilder()
.header("Cache-Control", "public, max-age=" + CACHE_MAX_AGE)ONE_WEEK).build();
}
}
}
can any one guide me through this ?
okhttp sends both if-modified-since date and if-none-match checksum headers in requests. There's usually no need for both and if-none-match is enough to figure out the version the client has. Sending both just confuses some http/1.1 server implementations
I have tried
builder = new Request.Builder().removeHeader("if-modified-since");
But that doesn't seem to do it. I assume the header is added later.
Is there a way to tell okhttp not to send if-modified-since ?
Yes. you can in builder.
You basically need to rebuild your request. Here is a complete sample:
httpClient.addInterceptor(new Interceptor() {
#Override
public okhttp3.Response intercept(Chain chain) throws IOException {
Request newRequest = chain
.request()
.newBuilder()
.removeHeader("if-modified-since")
.build();
return chain.proceed(newRequest);
}
});