導入 Http/http.dart 包時出錯 (error in importing Http/http.dart package)

問題描述

導入 Http/http.dart 包時出錯 (error in importing Http/http.dart package)

我用適當的縮進更新了依賴項，然後顫振 pub get 然後在代碼中導入它。也嘗試重新啟動我的ide。當我嘗試構建應用程序時彈出錯誤。

錯誤：

無法找到某些源的模塊，這通常是導入錯誤的結果，包中缺少依賴項（或者可能需要將 dev_dependency 移動到真正的依賴項），或者構建失敗（如果導入生成的文件）。

請檢查以下導入：

import 'package:http/http.dart' as http; from myapp|lib/myapp.dart at 83:1

Code:

    import 'package:flutter/material.dart';
    import 'package:http/http.dart' as http;
    import 'dart:convert';
    import 'dart:async';

     void main(){
       runApp(MaterialApp(
         home: HomePage(),
       ));
     }

     class HomePage extends StatefulWidget {

       @override
       _HomePageState createState() => _HomePageState();
     }

     class _HomePageState extends State<HomePage> {


       Future getData() async{
         http.Response response = await http.get("http://dummy.restapiexample.com/api/v1/employees");
         debugPrint(response.body);
       }

       @override
      void initState() {
        super.initState();
        getData();
      }

       @override
       Widget build(BuildContext context) {
         return Scaffold(
           appBar: AppBar(
             title: Text("Employees"),
             backgroundColor: Colors.green,
           ),
         );
       }
     }

pubspec.yaml

    name: myapp
    description: A new Flutter project.

    # The following defines the version and build number for your application.
    # A version number is three numbers separated by dots, like 1.2.43
    # followed by an optional build number separated by a +.
    # Both the version and the builder number may be overridden in flutter
    # build by specifying ‑‑build‑name and ‑‑build‑number, respectively.
    # In Android, build‑name is used as versionName while build‑number used as versionCode.
    # Read more about Android versioning at https://developer.android.com/studio/publish/versioning
    # In iOS, build‑name is used as CFBundleShortVersionString while build‑number used as CFBundleVersion.
    # Read more about iOS versioning at
    # https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
    version: 1.0.0+1

    environment:
      sdk: ">=2.1.0 <3.0.0"

    dependencies:
      flutter:
        sdk: flutter

      http: ^0.12.0+4

      # The following adds the Cupertino Icons font to your application.
      # Use with the CupertinoIcons class for iOS style icons.
      cupertino_icons: ^0.1.2

    dev_dependencies:
      flutter_test:
        sdk: flutter


    # For information on the generic Dart part of this file, see the
    # following page: https://dart.dev/tools/pub/pubspec

    # The following section is specific to Flutter.
    flutter:

      # The following line ensures that the Material Icons font is
      # included with your application, so that you can use the icons in
      # the material Icons class.
      uses‑material‑design: true

      # To add assets to your application, add an assets section, like this:
      # assets:
      #  ‑ images/a_dot_burr.jpeg
      #  ‑ images/a_dot_ham.jpeg

      # An image asset can refer to one or more resolution‑specific "variants", see
      # https://flutter.dev/assets‑and‑images/#resolution‑aware.

      # For details regarding adding assets from package dependencies, see
      # https://flutter.dev/assets‑and‑images/#from‑packages

      # To add custom fonts to your application, add a fonts section here,
      # in this "flutter" section. Each entry in this list should have a
      # "family" key with the font family name, and a "fonts" key with a
      # list giving the asset and other descriptors for the font. For
      # example:
      fonts:
        ‑ family: IndieFlower
          fonts:
            ‑ asset: fonts/IndieFlower‑Regular.ttf

      #
      # For details regarding fonts from package dependencies,
      # see https://flutter.dev/custom‑fonts/#from‑packages

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參考解法

方法 1:

Have you tried restarting your IDE?

https://flutter.dev/docs/development/packages‑and‑plugins/using‑packages

Stop and restart the app, if necessary If the package brings platform‑specific code (Java/Kotlin for Android, Swift/Objective‑C for iOS), that code must be built into your app. Hot reload and hot restart only update the Dart code, so a full restart of the app might be required to avoid errors like MissingPluginException when using the package.

方法 2:

I see your Flutter version is 1.13.6. I also experienced some strange problems with this version, but when I switched to dev channel all the problems are gone.

Try this too:

 flutter channel dev
 flutter upgrade

方法 3:

do not use vscode run&debug feature , use this command to run flutter run ‑d web‑server ‑‑web‑hostname= ‑‑web‑port= ‑‑profile ‑v ,replace "ipaddress" and "freeport" with your system input

(by Ankit Singh、Mário Garcia、Spatz、vikas bhutani)

參考文件

1. error in importing Http/http.dart package (CC BY‑SA 2.5/3.0/4.0)