OkCache is an open-source caching library for Android and JVM applications that leverages OkHttp to provide advanced HTTP caching strategies. It simplifies HTTP caching in your Retrofit APIs by allowing you to enable caching via annotations and choose from several fetch strategies, such as always fetching from the network, caching only, and various fallback approaches.

• Annotation-Driven Caching:
  Use the @Cached(maxAge = ...) annotation on your Retrofit API endpoints to enable caching with a specific expiration time.

• Multiple Fetch Strategies:
  Control caching behavior using fetch strategies:

  • NETWORK_ONLY: Always fetch fresh data from the network.
  • CACHE_ONLY: Use only the cached response; throw an error if unavailable.
  • NETWORK_FIRST: Try the network first; if that fails, fall back to the cache (if the cache is fresh).
  • CACHE_FIRST: Try the cache first; if the cache is empty or stale, perform a network call.
  • CACHE_STALE: Use the cached response even if stale.

• Interceptor-Based Implementation:
  Custom OkHttp interceptors (both request and network interceptors) manage caching policies based on the provided fetch strategy.

If you publish OkCache to Maven Central, add the dependency in your build.gradle.kts file:

dependencies {
    implementation("com.github.ktomek:okcache:1.0-SNAPSHOT")
}

Alternatively, if you’re using JitPack:

repositories {
    maven { url = uri("https://jitpack.io") }
}

dependencies {
    implementation("com.github.ktomek:okcache:1.0-SNAPSHOT")
}

Annotate your API methods with @Cached to activate caching. For example:

interface MyApiService {
    @Cached(maxAge = 60) // Cache for 60 seconds
    @GET("data")
    fun getData(): Call<MyData>
}

Set up your OkHttpClient with the request and network interceptors:

val networkInfoProvider: NetworkInfoProvider = YourNetworkInfoProvider()
val cacheDir = File(context.cacheDir, "http_cache")
val cacheSize = 10L * 1024 * 1024  // 10 MB

val okHttpClient = OkHttpClient.Builder()
    .cache(Cache(cacheDir, cacheSize))
    .addInterceptor(RequestCacheControlInterceptor(networkInfoProvider))
    .addNetworkInterceptor(ResponseCacheControlInterceptor())
    .build()

Initialize Retrofit with your customized OkHttpClient:

val retrofit = Retrofit.Builder()
    .baseUrl("https://api.example.com/")
    .client(okHttpClient)
    .addConverterFactory(GsonConverterFactory.create())
    .build()

val apiService = retrofit.create(MyApiService::class.java)

OkCache allows you to control the caching strategy at runtime using the FetchStrategy enum and a dedicated header.

interface MyApiService {
    @Cached(maxAge = 60)
    @GET("data")
    suspend fun getData(@Header(HEADER_FETCH_STRATEGY) strategy: FetchStrategy): MyData
}

val apiService = retrofit.create(MyApiService::class.java)

try {
    val result = apiService.getData(FetchStrategy.NETWORK_ONLY)
    // Handle successful result
} catch (e: DeviceOfflineException) {
    // No network available and cache fallback was not allowed
}

val apiService = retrofit.create(MyApiService::class.java)

try {
    val result = apiService.getData(FetchStrategy.CACHE_ONLY)
    // Handle successful result
} catch (e: NoCachedResponseException) {
    // Cache was required but not available
}

Contributions are welcome!
Please review our CONTRIBUTING.md for details on code style, testing, and how to submit pull requests.

This project is licensed under the MIT License.

MIT License

Copyright (c) 2023 ktomek

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