flutter_nayou/lib/app/core/dio_client.dart

import 'dart:io';

import 'package:connectivity_plus/connectivity_plus.dart';
import 'package:dio/dio.dart';
import 'package:flutter/cupertino.dart';

//import 'custom_interceptors.dart';

class DioClient {
  static final DioClient _instance = DioClient._internal();
  late Dio _dio;

  factory DioClient() => _instance;

  DioClient._internal() {
    _dio = Dio(BaseOptions(
      baseUrl: 'https://api.example.com', // 你的API地址
      connectTimeout: 5000,
      receiveTimeout: 3000,
    ));

    // 添加拦截器
    _dio.interceptors.add(CustomInterceptors());
  }

  Dio get dio => _dio;
}
class CustomInterceptors extends Interceptor {
  int _retryCount = 0;
  final List<String> _backupUrls = ['备用地址1', '备用地址2'];

  Future<bool> isConnected() async {
    var connectivityResult = await (Connectivity().checkConnectivity());
    return connectivityResult != ConnectivityResult.none;
  }

  @override
  Future<void> onError(DioError err, ErrorInterceptorHandler handler) async {
    // 检查网络连接状态
    bool isConnectNetWork = await isConnected();

    if (!isConnectNetWork) {
      // 无网络连接，设置友好的错误消息
      err.error = AppException(message: "当前网络不可用，请检查您的网络");
      return handler.next(err);
    } else if (err.error is SocketException || err.type == DioErrorType.other) {
      if (_retryCount < _backupUrls.length) {
        // 有网络连接但请求失败，尝试使用备用地址
        err.requestOptions.baseUrl = _backupUrls[_retryCount];
        _retryCount++;
        try {
          final Dio dio = Dio();
          final Response response = await dio.request<dynamic>(
            err.requestOptions.path,
            cancelToken: err.requestOptions.cancelToken,
            data: err.requestOptions.data,
            onReceiveProgress: err.requestOptions.onReceiveProgress,
            onSendProgress: err.requestOptions.onSendProgress,
            queryParameters: err.requestOptions.queryParameters,
            options: Options(
              method: err.requestOptions.method,
              headers: err.requestOptions.headers,
              contentType: err.requestOptions.contentType,
              responseType: err.requestOptions.responseType,
            ),
          );
          return handler.resolve(response);
        } catch (e) {
          return handler.next(err);
        }
      }
    }

    // 其他错误，统一处理
    AppException appException = AppException.create(err);
    debugPrint('DioError===: ${appException.toString()}');
    err.error = appException;
    return handler.next(err);
  }
}

class AppException implements Exception {
  final String message;
  AppException({required this.message});

  static AppException create(DioError err) {
    switch (err.type) {
      case DioErrorType.cancel:
        return AppException(message: '请求被取消');

      case DioErrorType.connectTimeout:
        return AppException(message: '连接超时');

      case DioErrorType.sendTimeout:
        return AppException(message: '请求超时');

      case DioErrorType.receiveTimeout:
        return AppException(message: '响应超时');

      case DioErrorType.response:
        return AppException(
          message: '服务器返回异常，状态码：${err.response?.statusCode}',
        );

      case DioErrorType.other:
        return AppException(
          message: '未知错误: ${err.message}',
        );

      default:
        return AppException(
          message: err.message,
        );
    }
  }

  @override
  String toString() {
    return message;
  }
}