swagger/lib/intercept.dart

import 'package:dio/dio.dart';
import 'package:flutter/material.dart';

class DioPage extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return _DioPageState();
  }
}

class _DioPageState extends State<DioPage> {

Dio dio = Dio(
  BaseOptions(
    baseUrl: 'http://localhost:8080/api/v1',
    connectTimeout: Durations.short4,
    receiveTimeout: Durations.short3,
  ),
);

Future<void> fetchData() async {
  try {
    Response response = await dio.get('http://localhost:8080/api/v1');
    print(response.data);
  } on DioException catch (e) {
    print(e.message);
  }
}

Future<void> postData() async {
  try {
    Response response = await dio.post(
      'http://localhost:8080/api/v1',
      data: {'key': 'value'},
    );
    print(response.data);
  } on DioException catch (e) {
    print(e.message);
  }
}

Future<String> refreshToken() async {
  // Perform a request to the refresh token endpoint and return the new access token.
  // You can replace this with your own implementation.
  return 'your_new_access_token';
}

  @override
  Widget build(BuildContext context) {
    Function(dynamic options, dynamic handler) onRequest;
    Future Function(DioException e, dynamic handler) onError;
    dio.interceptors.add(
  InterceptorsWrapper(
    onRequest:  onRequest = (options, handler) {
      // Add the access token to the request header
      options.headers['Authorization'] = 'Bearer your_access_token';
      return handler.next(options);
    },
    onError:  onError = (DioException e, handler) async {
      if (e.response?.statusCode == 401) {
        // If a 401 response is received, refresh the access token
        String newAccessToken = await refreshToken();

        // Update the request header with the new access token
        e.requestOptions.headers['Authorization'] = 'Bearer $newAccessToken';

        // Repeat the request with the updated header
        return handler.resolve(await dio.fetch(e.requestOptions));
      }
      return handler.next(e);
    },
  ),
);
    throw UnimplementedError();
  }


}