Retorfit2和OkHttp3缓存

朱雀 2022-06-05 06:49 189阅读 0赞

# Retorfit2和OkHttp3缓存 #

> 需求如下:当用户在有网络的情况下,设置一个”缓冲时间”,比如在请求了一次网络数据之后,接下来60s内进行网络请求其实是拿的缓存,这样做可以减少服务器负担,节约流量.  
> 当无网络时,用缓存读取数据,数据默认保存2周.这样就可以进行离线阅读.

## 1.首先来配置拦截器 ##

配置好时间等属性,再结合判断是否有网络来进行设置

public class RewriteCacheControlInterceptor implements Interceptor { 
    
        private Context mContext;
        /** * 无网络,设缓存有效期为两周 */
        private static final long CACHE_STALE_SEC = 60 * 60 * 24 * 14;
        /** * 有网 缓存60s */
        private static final long MAX_AGE = 60;
    
        public RewriteCacheControlInterceptor(Context context) {
            this.mContext = context;
        }
    
        @Override
        public Response intercept(Chain chain) throws IOException {
            Request request = chain.request();
            String cacheControl = request.cacheControl().toString();
            if (!DevicesUtils.hasNetworkConnected(mContext)) {
                request = request.newBuilder()
                        .cacheControl(TextUtils.isEmpty(cacheControl) ? CacheControl.FORCE_CACHE :
                                CacheControl.FORCE_NETWORK)
                        .build();
            }
            Response originalResponse = chain.proceed(request);
            if (DevicesUtils.hasNetworkConnected(mContext)) {
                //有网的时候连接服务器请求,缓存60s
                return originalResponse.newBuilder()
                        .header("Cache-Control", "public, max-age=" + MAX_AGE)
                        .removeHeader("Pragma")
                        .build();
            } else {
                //网络断开时读取缓存
                return originalResponse.newBuilder()
                        .header("Cache-Control", "public, only-if-cached, max-stale=" + CACHE_STALE_SEC)
                        .removeHeader("Pragma")
                        .build();
            }
        }
    }

## 2. 初始化OkHttp3 ##

将拦截器设置进去即可.

/** * 初始化OkHttp */
    public static void initOkHttp(Context context) {
        //拦截器
        RewriteCacheControlInterceptor mRewriteCacheControlInterceptor = new
                RewriteCacheControlInterceptor(context);
    
        //缓存文件
        File cacheFile = context.getCacheDir();
        //设置缓存大小
        Cache cache = new Cache(cacheFile, MAX_CACHE_SIZE);
        if (cacheFile != null) {
            okHttpClient = new OkHttpClient.Builder()
                    //超时设置
                    .readTimeout(READ_TIME_OUT, TimeUnit.SECONDS)
                    .connectTimeout(CONNECT_TIME_OUT, TimeUnit.SECONDS)
                    //错误重连
                    .retryOnConnectionFailure(true)
                    //拦截器
                    .addNetworkInterceptor(mRewriteCacheControlInterceptor)
                    .addInterceptor(mRewriteCacheControlInterceptor)
                    //缓存
                    .cache(cache)
                    .build();
        } else {
            okHttpClient = new OkHttpClient.Builder().build();
        }
    
    }