小编mrb*_*mrb的帖子

我的项目在调试模式下一切正常，但发布后，除了一个程序外，一切正常。

这是程序：

 Future<void> downloadFile() async{
Dio dio = Dio();

var directory = await getApplicationDocumentsDirectory();
await dio.download(bookUrl, "${directory.path}/$className + $bookName.pdf",
onReceiveProgress: (rec, total){
  setState(() {
    downloading = true;
    percentage = ((rec/total) * 100).toStringAsFixed(0)+'%';
  });
}

);

setState(() {
  downloading = false;
  percentage = 'Download Completed';
});

}

这是发布应用程序运行时我收到的错误消息：

E/flutter (25796): [ERROR:flutter/lib/ui/ui_dart_state.cc(148)] 未处理的异常：DioError [DioErrorType.DEFAULT]：SocketException：主机查找失败：'www.ets.org'（操作系统错误：没有与主机名关联的地址，errno = 7) E/flutter (25796): #0 Dio._makeRequest (package:dio/src/dio.dart:799) E/flutter (25796): E/flutter (25796): # 1 Dio._request.. (package:dio/src/dio.dart:711) E/flutter (25796): #2 _rootRunUnary (dart:async/zone.dart:1132) E/flutter (25796): #3 _CustomZone .runUnary (dart:async/zone.dart:1029) E/flutter (25796): …