使用 okhttp3 检查并恢复缓存文件

Question

I am using okhttp3 to make requests to the server, not using retrofit. My idea is to make a call and save the response in cache for 15 minutes. if during those 15 minutes, the request is made again, recover the cache response, after 15 minutes, request it again from the server.

This is my code:

public class Handler_JSON_get {

    public Handler_JSON_get() {

    }

    public String makeServiceCall(String url, JSONObject data) {
        final MediaType JSON = MediaType.parse("application/json; charset=utf-8");

        Cache cache = new Cache(new File(Environment.getExternalStorageDirectory().getPath() + "/Android/data/MY_PACKAGE/", "cache"), 10 * 1024 * 1024);

        OkHttpClient okHttpClient;

            Log.i("2134","Usando caché");
             okHttpClient = new OkHttpClient.Builder()
                    .addNetworkInterceptor(provideCacheInterceptor())
                    .readTimeout(45, TimeUnit.SECONDS)
                    .protocols(Arrays.asList(Protocol.HTTP_1_1))
                    .addInterceptor(provideCacheInterceptor())
                    .cache(cache)
                    .build();

        Request request = new Request.Builder()
                .url(url)
                .get()
                .build();

        try {
            Response response = okHttpClient.newCall(request).execute();

            Log.i(TAG,"Response:"+response.code());

            return response.body().string();
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }

    Interceptor provideCacheInterceptor() {
        return new Interceptor() {
            @Override
            public Response intercept(Interceptor.Chain chain) throws IOException {
                Response response = chain.proceed(chain.request());
                CacheControl cacheControl = new CacheControl.Builder()
                        .maxAge(15, TimeUnit.MINUTES)
                        .build();

                return response.newBuilder()
                        .header("cache", cacheControl.toString())
                        .build();
            }
        };
    }
}

The problem is that he always makes the call to the server and I have many doubts.

okhttp3 is responsible for seeing if there is a cached response in the storage?

The call saves a journal file, is this the correct file?

What am I missing or what am I doing wrong?

I have seen that there are quite a few questions about it, but I can not make those answers compatible with my code.

I would sincerely appreciate the parts that are necessary in my code to function properly, I start to go crazy.

Thanks in advance.

Answer 1

It took me some time to spot it : The correct header name is Cache-Control , not cache :

return response.newBuilder()
                    .header("Cache-Control", cacheControl.toString())
                    .build();

Also it seems that adding the interceptor with addNetworkInterceptor is sufficient, it is not necessary to also add it with addInterceptor