How to make use of cached data in my app?

Question

How to cache list data(images and names) in retrofit? Any suitable example for caching data will be more helpful?

Answer 1

ok. first of all you have to check headers coming in your api through postman. There you will see "Cache-Control" header. In this header, there has to be public cache value if you want to cache that api. Here is the code :

In your ApiClient.class where u kept your base URL, make this method :

public static CacheControl getCacheControl(CachePolicy cachePolicy) {
   switch (cachePolicy) {
       case CACHE_ONLY:
           return CacheControl.FORCE_CACHE;
       case NETWORK_ONLY:
           return CacheControl.FORCE_NETWORK;

       case NETWORK_ELSE_CACHE:
           return new CacheControl.Builder().maxAge(1, TimeUnit.MINUTES).maxStale(1, TimeUnit.MINUTES).build();

       case FRESH_CASHE_ELSE_NETWORK:
           return new CacheControl.Builder().maxAge(1, TimeUnit.MINUTES).minFresh(1, TimeUnit.MINUTES).build();


       case CACHE_ELSE_NETWORK:
          return new CacheControl.Builder().immutable().build();

   }
   return null;

}

Now make an enum class to keep these constants :

 public enum CachePolicy {
 CACHE_ONLY,
 NETWORK_ONLY,
 NETWORK_ELSE_CACHE,
 FRESH_CASHE_ELSE_NETWORK,
 CACHE_ELSE_NETWORK
 }

Paste this method in your ApiClient class with your base url :

public static Retrofit getClientAuthenticationWithCache(Context context, CacheControl
       cacheControl) {
   String URL_BASE = "your base url";
   long cacheSize = 10 * 1024 * 1024;  //10MiB
   Cache cache = new Cache(context.getCacheDir(), cacheSize);



   Interceptor interceptor = new Interceptor() {
       @Override
       public Response intercept(Chain chain) throws IOException {
           Request request = chain.request();
           request = request.newBuilder().cacheControl(cacheControl).build();
           return chain.proceed(request);
       }
   };

   OkHttpClient okHttpClient = new OkHttpClient.Builder()
           .cache(cache)
           .addInterceptor(interceptor)
           .build();

   Retrofit.Builder builder = new Retrofit.Builder()
           .baseUrl(URL_BASE)
           .client(okHttpClient)
           .addConverterFactory(GsonConverterFactory.create());

   return builder.build();

}

Now use this method in the activity/fragment where you are getting response as follow :

ApiClient.getClient(applicationContext, ApiClient.getCacheControl(CachePolicy.NETWORK_ELSE_CACHE)).create(ApiInterface::class.java)