import 'package:dio/dio.dart';

class CacheInterceptor extends Interceptor {

CacheInterceptor();

final _cache = <Uri, Response>{};

@override

void onRequest(RequestOptions options, RequestInterceptorHandler handler) {

final response = _cache[options.uri];

if (options.extra['refresh'] == true) {

print('${options.uri}: force refresh, ignore cache! \n');

return handler.next(options);

} else if (response != null) {

print('cache hit: ${options.uri} \n');

return handler.resolve(response);

}

super.onRequest(options, handler);

}

@override

void onResponse(Response response, ResponseInterceptorHandler handler) {

_cache[response.requestOptions.uri] = response;

super.onResponse(response, handler);

}

@override

void onError(DioException err, ErrorInterceptorHandler handler) {

print('onError: $err');

super.onError(err, handler);

}

}

void main() async {

final dio = Dio();

dio.options.baseUrl = 'https://pub.dev';

dio.interceptors

..add(CacheInterceptor())

..add(LogInterceptor(requestHeader: false, responseHeader: false));

await dio.get('/'); // second request

await dio.get('/'); // Will hit cache

// Force refresh

await dio.get('/', options: Options(extra: {'refresh': true}));

}