如何处理 http 错误（FormatException: Unexpected end of input (at character 1)）答案

【问题标题】：How to handle http errors (FormatException: Unexpected end of input (at character 1))如何处理 http 错误（FormatException: Unexpected end of input (at character 1)）
【发布时间】：2019-10-08 11:14:22
【问题描述】：

如何处理这种错误信息？为什么会来？是那个问题吗？我每 10 秒调用一次下面的方法。

   checkQuick(String url, String token) async {
    result =
        (await HelperDatabase1().displayGetUserPreference()).elementAt(0)?.data;
    final response = await http.get(
      '$url/nativeapi/v1.0/User/GetUserPreference',
      headers: {'Authorization': 'Bearer $token'},
    );
    final jsonResponse = json.decode(response.body);
    GetUserPreference model = GetUserPreference.fromJson(jsonResponse);
    var data = GetUserPreference(data: model.data);
    //result = data.data;

      if (result != data.data) {
     //  await HelperDatabase1().updateGetUserPreference(1, data.data);
        print('inside');
        await HelperDatabase1().deleteGetUserPreference();
        await HelperDatabase1().storeGetUserPreference(url, token);
      }
  }

有时会出现以下错误消息。

E/flutter ( 7148): [ERROR:flutter/lib/ui/ui_dart_state.cc(148)] Unhandled Exception: FormatException: Unexpected end of input (at character 1)
E/flutter ( 7148): 
E/flutter ( 7148): ^
E/flutter ( 7148):

E/flutter (7148): #0 _ChunkedJsonParser.fail (dart:convert-patch/convert_patch.dart:1392:5) E/flutter (7148): #1
_ChunkedJsonParser.close (dart:convert-patch/convert_patch.dart:510:7) E/flutter (7148): #2 _parseJson (dart:convert-patch/convert_patch.dart:30:10) E/flutter (7148): #3
JsonDecoder.convert (dart:convert/json.dart:493:36) E/flutter (7148):

4 JsonCodec.decode (dart:convert/json.dart:151:41) E/flutter (7148): #5 _ListPageState.checkQuick

(package:reborn_next_job02/ui/AssetRegisters.dart:153:31) E/flutter ( 7148）：E/颤振（7148）：#6
_ListPageState.initState。 (包:reborn_next_job02/ui/AssetRegisters.dart:47:7) E/flutter ( 7148): #7 _rootRunUnary (dart:async/zone.dart:1132:38) E/flutter (7148):#8 _CustomZone.runUnary (dart:async/zone.dart:1029:19) E/颤振（7148）：#9 _CustomZone.runUnaryGuarded (dart:async/zone.dart:931:7) E/flutter (7148): #10
_CustomZone.bindUnaryCallbackGuarded。 (dart:async/zone.dart:968:26) E/flutter (7148): #11 _rootRunUnary (dart:async/zone.dart:1136:13) E/flutter (7148): #12
_CustomZone.runUnary (dart:async/zone.dart:1029:19) E/flutter (7148): #13 _CustomZone.bindUnaryCallback。 (dart:async/zone.dart:952:26) E/flutter (7148): #14
_Timer._runTimers (dart:isolate-patch/timer_impl.dart:382:19) E/flutter (7148): #15 _Timer._handleMessage (dart:isolate-patch/timer_impl.dart:416:5) E/flutter (7148): #16
_RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:171:12)

【问题讨论】：

标签： dart flutter flutter-dependencies

【解决方案1】：

检查之前的 response.statusCode 是否为 200。貌似response.body是空的，因为调用失败，所以json.decode(response.body)抛出异常。

【讨论】：