Flutter：一个程序在调试模式下运行良好，但在发布后运行良好，为什么？

Question

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): #4 _FutureListener.handleValue (dart:async/future_impl.dart:126) E/flutter (25796): #5
Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:639) E/flutter (25796): #6
Future._propagateToListeners (dart:async/future_impl.dart:668) E/flutter (25796): #7 Future._complete (dart:async/future_impl.dart:473) E/flutter (25796): #8
_SyncCompleter.complete ( dart:async/future_impl.dart:51) E/flutter (25796): #9 _AsyncAwaitCompleter.complete。(dart:async-patch/async_patch.dart:33) E/flutter (25796): #10
_rootRun (dart:async/zone.dart:1120) E/flutter (25796): #11 _CustomZone.run (dart:async /zone.dart:1021) E/flutter (25796): #12 _CustomZone.runGuarded (dart:async/zone.dart:923) E/flutter (25796): #13 _CustomZone.bindCallbackGuarded。(dart:async/zone.dart:963) E/flutter (25796): #14 _rootRun (dart:async/zone.dart:1124) E/flutter (25796): #15 _CustomZone.run (dart:async/zone .dart:1021) E/flutter (25796): #16
_CustomZone.runGuarded (dart:async/zone.dart:923) E/flutter (25796)：#17 _CustomZone.bindCallbackGuarded。(dart:async/zone.dart:963) E/flutter (25796): #18 _microtaskLoop (dart:async/schedule_microtask.dart:41) E/flutter (25796): #19
_startMicrotaskLoop (dart:async/schedule_microtask.dart :50)

Answer 1

确保你有

<uses-permission android:name="android.permission.INTERNET" />

在您的应用程序的 android/app/src/main/AndroidManifest.xml 中