时间戳

首页 > 解决方案 > Dart - 无法从连接流中捕获异常

flutter - Dart - 无法从连接流中捕获异常

问题描述

我无法捕获connectivity.onConnectivityChanged.listen函数内抛出的异常。我尝试过使用 try-catch 块和onError函数，但我无法让它们工作。有人知道我做错了什么吗？

import 'package:flutter/foundation.dart';
import 'dart:async';

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

class DioConnectivityRequestRetrier {
  final Dio dio;
  final Connectivity connectivity;

  DioConnectivityRequestRetrier({
    @required this.dio,
    @required this.connectivity,
  });

  Future<Response> scheduleRequestRetry(RequestOptions requestOptions) async {
    StreamSubscription streamSubscription;
    final responseCompleter = Completer<Response>();
    try {
      connectivity.onConnectivityChanged.listen(
        (connectivityResult) {
          if (connectivityResult != ConnectivityResult.none) {
            // streamSubscription.cancel();

            // An exception when dio.request fails
            throw Exception;

            responseCompleter.complete(
              dio.request(
                requestOptions.path,
                cancelToken: requestOptions.cancelToken,
                data: requestOptions.data,
                onReceiveProgress: requestOptions.onReceiveProgress,
                onSendProgress: requestOptions.onSendProgress,
                queryParameters: requestOptions.queryParameters,
                options: requestOptions,
              ),
            );
          }
        },
      ).onError((e) {
        throw e;
      });
    } catch (e) {
      rethrow;
    }

    return responseCompleter.future;
  }
}

抛出异常时调试控制台的输出connectivity.onConnectivityChanged.listen：

E/flutter ( 8336): [ERROR:flutter/lib/ui/ui_dart_state.cc(177)] Unhandled Exception: Exception
E/flutter ( 8336): #0      DioConnectivityRequestRetrier.scheduleRequestRetry.<anonymous closure>
package:eindproduct/…/interceptor/dio_connectivity_request_retrier.dart:26
E/flutter ( 8336): #1      _rootRunUnary (dart:async/zone.dart:1198:47)
E/flutter ( 8336): #2      _CustomZone.runUnary (dart:async/zone.dart:1100:19)
E/flutter ( 8336): #3      _CustomZone.runUnaryGuarded (dart:async/zone.dart:1005:7)
E/flutter ( 8336): #4      _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:357:11)
E/flutter ( 8336): #5      _BufferingStreamSubscription._add (dart:async/stream_impl.dart:285:7)
E/flutter ( 8336): #6      _ForwardingStreamSubscription._add (dart:async/stream_pipe.dart:127:11)
E/flutter ( 8336): #7      _MapStream._handleData (dart:async/stream_pipe.dart:224:10)
E/flutter ( 8336): #8      _ForwardingStreamSubscription._handleData (dart:async/stream_pipe.dart:157:13)
E/flutter ( 8336): #9      _rootRunUnary (dart:async/zone.dart:1198:47)
E/flutter ( 8336): #10     _CustomZone.runUnary (dart:async/zone.dart:1100:19)
E/flutter ( 8336): #11     _CustomZone.runUnaryGuarded (dart:async/zone.dart:1005:7)
E/flutter ( 8336): #12     _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:357:11)
E/flutter ( 8336): #13     _BufferingStreamSubscription._add (dart:async/stream_impl.dart:285:7)
E/flutter ( 8336): #14     _ForwardingStreamSubscription._add (dart:async/stream_pipe.dart:127:11)
E/flutter ( 8336): #15     _MapStream._handleData (dart:async/stream_pipe.dart:224:10)
E/flutter ( 8336): #16     _ForwardingStreamSubscription._handleData (dart:async/stream_pipe.dart:157:13)
E/flutter ( 8336): #17     _rootRunUnary (dart:async/zone.dart:1198:47)
E/flutter ( 8336): #18     _CustomZone.runUnary (dart:async/zone.dart:1100:19)
E/flutter ( 8336): #19     _CustomZone.runUnaryGuarded (dart:async/zone.dart:1005:7)
E/flutter ( 8336): #20     _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:357:11)
E/flutter ( 8336): #21     _DelayedData.perform (dart:async/stream_impl.dart:611:14)
E/flutter ( 8336): #22     _StreamImplEvents.handleNext (dart:async/stream_impl.dart:730:11)
E/flutter ( 8336): #23     _PendingEvents.schedule.<anonymous closure> (dart:async/stream_impl.dart:687:7)
E/flutter ( 8336): #24     _rootRun (dart:async/zone.dart:1182:47)
E/flutter ( 8336): #25     _CustomZone.run (dart:async/zone.dart:1093:19)
E/flutter ( 8336): #26     _CustomZone.runGuarded (dart:async/zone.dart:997:7)
E/flutter ( 8336): #27     _CustomZone.bindCallbackGuarded.<anonymous closure> (dart:async/zone.dart:1037:23)
E/flutter ( 8336): #28     _rootRun (dart:async/zone.dart:1190:13)
E/flutter ( 8336): #29     _CustomZone.run (dart:async/zone.dart:1093:19)
E/flutter ( 8336): #30     _CustomZone.runGuarded (dart:async/zone.dart:997:7)
E/flutter ( 8336): #31     _CustomZone.bindCallbackGuarded.<anonymous closure> (dart:async/zone.dart:1037:23)
E/flutter ( 8336): #32     _microtaskLoop (dart:async/schedule_microtask.dart:41:21)
E/flutter ( 8336): #33     _startMicrotaskLoop (dart:async/schedule_microtask.dart:50:5)

标签： flutterdartstreamtry-catchconnectivity

解决方案

尝试这样的事情：

try {
     /// YOUR CODE HERE ///
    } on PlatformException catch (e) {
      print(e.toString());
    }

推荐阅读