改造響應緩存

Question

這里有很多關於Retrofit緩存的復雜答案，但似乎都沒有幫助我。

如何緩存來自Retrofit響應的代碼響應？

我的應用程序可以正常下載下面的JSON，但我需要為它做一個緩存，我從來沒有在Android上進行緩存。

我需要離線打開應用程序並從我的Retrofit調用中獲取結果，就好像我在線一樣。

public class APIClient {

public static final String BASE_URL = "https://raw.githubusercontent.com/";
private static Retrofit retrofit = null;

public static Retrofit getClient() {
    if (retrofit==null) {
        OkHttpClient.Builder httpClient = new OkHttpClient.Builder();
        httpClient.addInterceptor(new Interceptor() {
            @Override
            public Response intercept(Interceptor.Chain chain) throws IOException {
                Request original = chain.request();

                Request request = original.newBuilder()
                        .method(original.method(), original.body())
                        .build();
                return chain.proceed(request);
            }
        });

        OkHttpClient client = httpClient.build();
        retrofit = new Retrofit.Builder()
                .baseUrl(BASE_URL)
                .addConverterFactory(GsonConverterFactory.create())
                .client(client)
                .build();
    }
    return retrofit;
}}

json響應非常簡單：

 { "fruits":[ { "name":"Apple", "image":"https://upload.wikimedia.org/wikipedia/commons/thumb/1/15/Red_Apple.jpg/265px-Red_Apple.jpg", "price":35 }, { "name":"Banana", "image":"https://upload.wikimedia.org/wikipedia/commons/thumb/4/44/Bananas_white_background_DS.jpg/320px-Bananas_white_background_DS.jpg", "price":12 }, { "name":"Grapes", "image":"https://upload.wikimedia.org/wikipedia/commons/thumb/b/bb/Table_grapes_on_white.jpg/320px-Table_grapes_on_white.jpg", "price":45 }, { "name":"Pineapple", "image":"https://upload.wikimedia.org/wikipedia/commons/thumb/c/cb/Pineapple_and_cross_section.jpg/286px-Pineapple_and_cross_section.jpg", "price":200 }, { "name":"cherry", "image":"http://www.desicomments.com/wp-content/uploads/2017/05/Cherry-Image-600x570.jpg", "price":13 }, { "name":"clementine", "image":"http://www.icecreamnation.org/wp-content/uploads/2013/04/Clementine_orange.jpg", "price":12.4 }, { "name":"olive", "image":"https://www.homenaturalcures.com/wp-content/uploads/olive.jpg", "price":9.5 }, { "name":"tomato", "image":"http://cdn2.stylecraze.com/wp-content/uploads/2013/05/tomato-hair-benefits1.jpg", "price":8.75 }, { "name":"huckleberry", "image":"http://farm3.static.flickr.com/2131/2082287810_47339fc93e.jpg", "price":11.75 }, { "name":"papaya", "image":"http://media.mercola.com/assets/images/foodfacts/papaya-nutrition-facts.jpg", "price":2.75 }, { "name":"lime", "image":"https://www.florihana.com/images/stories/virtuemart/product/FLE019%20-%20LIME.jpg", "price":5.75 }, { "name":"pear", "image":"https://www.organicfacts.net/wp-content/uploads/pear.jpg", "price":4.75 } ] } 

Answer 1

假設服務器遵循Cache-Control / If-Modified-Since標頭，那么您所要做的就是創建一個Cache對象並將其設置為OkHttpClient 。 改造將照顧其余部分。

    int cacheSize = 10 * 1024 * 1024; // 10 MB  
    Cache cache = new Cache(getCacheDir(), cacheSize);

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

    Retrofit.Builder builder = new Retrofit.Builder()  
            .baseUrl("http://10.0.2.2:3000/")
            .client(okHttpClient)
            .addConverterFactory(GsonConverterFactory.create());

    Retrofit retrofit = builder.build();

^{資料來源： futurestud.io}

Answer 2

使用retrofit 2.0和okHttp來緩存我們的服務器響應，我們都需要的是OkHttpClient，AddNetworkInterceptor添加緩存攔截器，你無法使用。 AddInterceptor，也不需要同時進行。

此方法不需要服務器端操作，也不需要其他服務器端緩存策略，如果服務器有自己的緩存策略，則應相應地修改代碼以適應服務器。

你可以參考這個鏈接，它幫助我解決了我的問題