在pubspec.yaml文件中加入对这个插件的依赖：

dependencies:
  connectivity: ^0.4.2

终端

flutter packages get

代码判断

import 'package:connectivity/connectivity.dart';

//网络状态
    String netWork;
    var connectivityResult = await (Connectivity().checkConnectivity());
    if (connectivityResult == ConnectivityResult.mobile) {
      netWork = '4G';
      // 网络类型为移动网络
    } else if (connectivityResult == ConnectivityResult.wifi) {
      // 网络类型为WIFI
      netWork = 'WIFI';
    } else {
      netWork = 'NotReachable';
    }
    print('connectivityResult--->$connectivityResult;netWork----->$netWork');

如果运行出错出现

MissingPluginException(No implementation found for method check on channel xxx)

解决方案
https://blog.csdn.net/timtian008/article/details/105701459