我想在每个 dio 请求之前使用 flutter 中的拦截器和连接包检查互联网连接

1.首先你应该将包安装到你的项目中，你可以使用下面的cammand添加它，connectivity

flutter pub add connectivity_plus

2.现在您应该导入到您的工作区中。进口

'package:connectivity_plus/connectivity_plus.dart';

您可以使用此链接引用它。

3.设置拦截器以在每个 Dio 请求之前检查互联网连接。创建一个从 Dio 包扩展的类：查看下面的代码段，Interceptor

import 'package:dio/dio.dart';
import 'package:connectivity/connectivity.dart';

class ConnectivityInterceptor extends Interceptor {
  final Connectivity connectivity;

  ConnectivityInterceptor(this.connectivity);

  @override
  Future onRequest(RequestOptions options, RequestInterceptorHandler handler) async {
    var connectivityResult = await connectivity.checkConnectivity();
    if (connectivityResult == ConnectivityResult.none) {
      // Handle case when there is no internet connection
      throw DioError(
        requestOptions: options,
        response: Response(
          requestOptions: options,
          statusCode: 503, // You can set your custom status code
          statusMessage: 'No internet connection',
        ),
      );
    }
    return super.onRequest(options, handler);
  }
}

4.In 您的主要函数或配置 Dio 的位置，请使用拦截器设置 Dio 实例：

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

void main() {
  Dio dio = Dio();
  Connectivity connectivity = Connectivity();
  dio.interceptors.add(ConnectivityInterceptor(connectivity));
  
  runApp(MyApp(dio: dio));
}

class MyApp extends StatelessWidget {
  final Dio dio;

  MyApp({required this.dio});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('Dio Connectivity Example'),
        ),
        body: Center(
          child: ElevatedButton(
            onPressed: () {
              makeDioRequest();
            },
            child: Text('Make Dio Request'),
          ),
        ),
      ),
    );
  }

  Future<void> makeDioRequest() async {
    try {
      Response response = await dio.get('https://api.example.com/data');
      print('Response: ${response.data}');
      // Handle the response
    } on DioError catch (e) {
      if (e.response != null && e.response!.statusCode == 503) {
        // Handle case when there is no internet connection
        print('No internet connection');
        // Show a dialog or snackbar indicating no internet
      } else {
        // Handle other Dio errors
        print('Dio error: $e');
        // Show a dialog or snackbar with the error
      }
    }
  }
}

class ConnectivityInterceptor extends Interceptor {
  final Connectivity connectivity;

  ConnectivityInterceptor(this.connectivity);

  @override
  Future onRequest(RequestOptions options, RequestInterceptorHandler handler) async {
    var connectivityResult = await connectivity.checkConnectivity();
    if (connectivityResult == ConnectivityResult.none) {
      // Handle case when there is no internet connection
      throw DioError(
        requestOptions: options,
        response: Response(
          requestOptions: options,
          statusCode: 503, // You can set your custom status code
          statusMessage: 'No internet connection',
        ),
      );
    }
    return super.onRequest(options, handler);
  }
}

我使用带有按钮的简单应用程序，您可以使用此指南给出一些想法。

我不知道您为什么要使用 and 包的目的（如果您有特定目的，请忽略答案），但为了简单地检查互联网连接是否可用，我使用库如下：interceptorconnectivityInternetAddress.lookupdart:io

/// [_isInternetAvailable] Checks if the
/// internet connection is available or not.
Future<bool> _isInternetAvailable() async {
  try {
    final foo = await InternetAddress.lookup('google.com');
    return foo.isNotEmpty && foo[0].rawAddress.isNotEmpty ? true : false;
  } catch (e) {
    return false;
  }
}