Flutter http post给出错误但在邮递员中有效答案

【问题标题】：Flutter http post gives error but works in postmanFlutter http post给出错误但在邮递员中有效
【发布时间】：2019-06-22 19:59:41
【问题描述】：

我正在尝试向响应如下所示的 url 发出 post 请求

{"status":1,"msg":"Success"}

以下是我的代码

void signOut(String userId, String loginType, BuildContext context) async {
    print(userId + "\nFargo" + loginType);
    await checkInternetConnection().then((isAvailable) async {
      if (isAvailable) {
        //ToDO showProgress Bar
        final response = await http.post(SIGN_OUT_URL, headers: {
          "Accept": "application/json",
        }, body: {
          "userid": userId,
          "login_type": loginType
        });

        print("Response is" +
            response.body.toString() +
            "\nfgfdgfdgdf" +
            response.request.toString());

        final parsedJson = json.decode(response.body);
        signOutModel = SignOutModel.fromJson(parsedJson);
        if (signOutModel.status == 1) {

          //ToDO hide Progress Bar
        } else {
          //ToDO hide Progress Bar
          showMessageDialog(signOutModel.msg, context);
        }
      } else {
        showMessageDialog(CHECK_YOUR_INTERNET_CONNECTION, context);
      }
    });
  }

但是每当提出请求时，我都会收到以下错误

[

ERROR:flutter/shell/common/shell.cc(184)] Dart Error: Unhandled exception:
E/flutter ( 7932): FormatException: Unexpected character (at character 1)
E/flutter ( 7932): <!DOCTYPE html>
E/flutter ( 7932): ^
E/flutter ( 7932): 
E/flutter ( 7932): #0      _ChunkedJsonParser.fail (dart:convert/runtime/libconvert_patch.dart:1358:5)
E/flutter ( 7932): #1      _ChunkedJsonParser.parseNumber (dart:convert/runtime/libconvert_patch.dart:1254:9)
E/flutter ( 7932): #2      _ChunkedJsonParser.parse (dart:convert/runtime/libconvert_patch.dart:922:22)
E/flutter ( 7932): #3      _parseJson (dart:convert/runtime/libconvert_patch.dart:29:10)
E/flutter ( 7932): #4      JsonDecoder.convert (dart:convert/json.dart:540:36)
E/flutter ( 7932): #5      JsonCodec.decode (dart:convert/json.dart:167:41)
E/flutter ( 7932): #6      BaseScreenState.signOut.<anonymous closure> (package:dice_clutter/screens/base/base_screen.dart:223:33)
E/flutter ( 7932): <asynchronous suspension>
E/flutter ( 7932): #7      _RootZone.runUnary (dart:async/zone.dart:1379:54)
E/flutter ( 7932): #8      _FutureListener.handleValue (dart:async/future_impl.dart:129:18)
E/flutter ( 7932): #9      Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:642:45)
E/flutter ( 7932): #10     Future._propagateToListeners (dart:async/future_impl.dart:671:32)
E/flutter ( 7932): #11     Future._complete (dart:async/future_impl.dart:476:7)
E/flutter ( 7932): #12     _SyncCompleter.complete (dart:async/future_impl.dart:51:12)
E/flutter ( 7932): #13     _AsyncAwaitCompleter.complete (dart:async/runtime/libasync_patch.dart:28:18)
E/flutter ( 7932): #14     _completeOnAsyncReturn (dart:async/runtime/libasync_patch.dart:295:13)
E/flutter ( 7932): #15     checkInternetConnection (package:dice_clutter/helpers/internet_connection.dart)
E/flutter ( 7932): <asynchronous suspension>
E/flutter ( 7932): #16     BaseScreenState.signOut (package:dice_clutter/screens/base/base_screen.dart:208:11)
E/flutter ( 7932): <asynchronous suspension>
E/flutter ( 7932): #17     BaseScreenState.openScreen (package:dice_clutter/screens/base/base_screen.dart:202:7)
E/flutter ( 7932): #18     BaseScreenState.build.<anonymous closure>.<anonymous closure> (package:dice_clutter/screens/base/base_screen.dart:90:19)
E/flutter ( 7932): #19     _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:507:14)
E/flutter ( 7932): #20     _InkResponseState.build.<anonymous closure> (package:flutter/src/material/ink_well.dart:562:30)
E/flutter ( 7932): #21     GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:102:24)
E/flutter ( 7932): #22     TapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:242:9)
E/flutter ( 7932): #23     TapGestureRecognizer.acceptGesture (package:flutter/src/gestures/tap.dart:204:7)
E/flutter ( 7932): #24     GestureArenaManager.sweep (package:flutter/src/gestures/arena.dart:156:27)
E/flutter ( 7932): #25     _WidgetsFlutterBinding&BindingBase&GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:184:20)
E/flutter ( 7932): #26     _WidgetsFlutterBinding&BindingBase&GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:158:22)
E/flutter ( 7932): #27     _WidgetsFlutterBinding&BindingBase&GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:138:7)
E/flutter ( 7932): #28     _WidgetsFlutterBinding&BindingBase&GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:101:7)
E/flutter ( 7932): #29     _WidgetsFlutterBinding&BindingBase&GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:85:7)
E/flutter ( 7932): #30     _invoke1 (dart:ui/hooks.dart:168:13)
E/flutter ( 7932): #31     _dispatchPointerDataPacket (dart:ui/hooks.dart:122:5)

api 通过邮递员正常工作，我检查了我在 post 请求中输入的 url 和参数它们与邮递员的相同，但我仍然不断收到错误。

【问题讨论】：

服务器正在响应 HTML 而不是 JSON。你从中看到了什么：print("Response is" + response.body.toString() +？让它在 Postman 中工作很有用 - 所以请使用 Postman 配置的屏幕截图编辑问题。尝试将问题简化为最小示例。

标签： http dart flutter

【解决方案1】：

您的请求正文不是 JSON 字符串。您必须先使用dart:convert 包进行转换：

import 'dart:convert';
..
var body = jsonEncode({
  "userid": userId,
  "login_type": loginType
})
final response = await http.post(SIGN_OUT_URL, headers: {
  "Accept": "application/json",
  }, body: body
);

【讨论】：

感谢您的回答，但 json.encode 和 jsonEncode 之间的区别以及何时使用哪个
从导入 'dart:convert';图书馆
尝试在标题中将标题Content-Type 设置为application/json
在你的代码中这个打印的输出是什么：print("Response is" + response.body.toString() + "\nfgfdgfdgdf" + response.request.toString()); ?