HTTP通信をやってみる

Flutter: 2.8.0を使用

こちらのサイトのAPIを使用
https://reqres.in/

pabspec.yaml

name: getx_app
description: A new Flutter project.

# The following line prevents the package from being accidentally published to
# pub.dev using `flutter pub publish`. This is preferred for private packages.
publish_to: 'none' # Remove this line if you wish to publish to pub.dev

# 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: ">=2.15.0 <3.0.0"

# Dependencies specify other packages that your package needs in order to work.
# To automatically upgrade your package dependencies to the latest versions
# consider running `flutter pub upgrade --major-versions`. Alternatively,
# dependencies can be manually updated by changing the version numbers below to
# the latest version available on pub.dev. To see which dependencies have newer
# versions available, run `flutter pub outdated`.
dependencies:
  flutter:
    sdk: flutter


  # The following adds the Cupertino Icons font to your application.
  # Use with the CupertinoIcons class for iOS style icons.
  cupertino_icons: ^1.0.2
  http: ^0.13.4

dev_dependencies:
  flutter_test:
    sdk: flutter

  # The "flutter_lints" package below contains a set of recommended lints to
  # encourage good coding practices. The lint set provided by the package is
  # activated in the `analysis_options.yaml` file located at the root of your
  # package. See that file for information about deactivating specific lint
  # rules and activating additional ones.
  flutter_lints: ^1.0.0

# 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: Schyler
  #     fonts:
  #       - asset: fonts/Schyler-Regular.ttf
  #       - asset: fonts/Schyler-Italic.ttf
  #         style: italic
  #   - family: Trajan Pro
  #     fonts:
  #       - asset: fonts/TrajanPro.ttf
  #       - asset: fonts/TrajanPro_Bold.ttf
  #         weight: 700
  #
  # For details regarding fonts from package dependencies,
  # see https://flutter.dev/custom-fonts/#from-packages

main.dart

import 'dart:convert';

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

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.indigo,
      ),
      home: const MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {
  const MyHomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Future Builder"),
      ),
      body: Center(
        child: ElevatedButton(
          onPressed: () async {
            // get data url api
            var response =
                await http.get(Uri.parse("https://reqres.in/api/users"));
            List data =
                (json.decode(response.body) as Map<String, dynamic>)["data"];
            data.forEach((element) {
              Map<String, dynamic> user = element;
              print(user);
            });
          },
          child: Text("KLIK"),
        ),
      ),
    );
  }
}

実行結果

flutter: [{id: 1, email: george.bluth@reqres.in, first_name: George, last_name: Bluth, avatar: https://reqres.in/img/faces/1-image.jpg}, {id: 2, email: janet.weaver@reqres.in, first_name: Janet, last_name: Weaver, avatar: https://reqres.in/img/faces/2-image.jpg}, {id: 3, email: emma.wong@reqres.in, first_name: Emma, last_name: Wong, avatar: https://reqres.in/img/faces/3-image.jpg}, {id: 4, email: eve.holt@reqres.in, first_name: Eve, last_name: Holt, avatar: https://reqres.in/img/faces/4-image.jpg}, {id: 5, email: charles.morris@reqres.in, first_name: Charles, last_name: Morris, avatar: https://reqres.in/img/faces/5-image.jpg}, {id: 6, email: tracey.ramos@reqres.in, first_name: Tracey, last_name: Ramos, avatar: https://reqres.in/img/faces/6-image.jpg}]
Reloaded 1 of 638 libraries in 279ms.
2
flutter: {id: 1, email: george.bluth@reqres.in, first_name: George, last_name: Bluth, avatar: https://reqres.in/img/faces/1-image.jpg}
Reloaded 1 of 638 libraries in 204ms.
flutter: {id: 1, email: george.bluth@reqres.in, first_name: George, last_name: Bluth, avatar: https://reqres.in/img/faces/1-image.jpg}
flutter: {id: 2, email: janet.weaver@reqres.in, first_name: Janet, last_name: Weaver, avatar: https://reqres.in/img/faces/2-image.jpg}
flutter: {id: 3, email: emma.wong@reqres.in, first_name: Emma, last_name: Wong, avatar: https://reqres.in/img/faces/3-image.jpg}
flutter: {id: 4, email: eve.holt@reqres.in, first_name: Eve, last_name: Holt, avatar: https://reqres.in/img/faces/4-image.jpg}
flutter: {id: 5, email: charles.morris@reqres.in, first_name: Charles, last_name: Morris, avatar: https://reqres.in/img/faces/5-image.jpg}
flutter: {id: 6, email: tracey.ramos@reqres.in, first_name: Tracey, last_name: Ramos, avatar: https://reqres.in/img/faces/6-image.jpg}
flutter: {id: 1, email: george.bluth@reqres.in, first_name: George, last_name: Bluth, avatar: https://reqres.in/img/faces/1-image.jpg}
flutter: {id: 2, email: janet.weaver@reqres.in, first_name: Janet, last_name: Weaver, avatar: https://reqres.in/img/faces/2-image.jpg}
flutter: {id: 3, email: emma.wong@reqres.in, first_name: Emma, last_name: Wong, avatar: https://reqres.in/img/faces/3-image.jpg}
flutter: {id: 4, email: eve.holt@reqres.in, first_name: Eve, last_name: Holt, avatar: https://reqres.in/img/faces/4-image.jpg}
flutter: {id: 5, email: charles.morris@reqres.in, first_name: Charles, last_name: Morris, avatar: https://reqres.in/img/faces/5-image.jpg}
flutter: {id: 6, email: tracey.ramos@reqres.in, first_name: Tracey, last_name: Ramos, avatar: https://reqres.in/img/faces/6-image.jpg}
flutter: {id: 1, email: george.bluth@reqres.in, first_name: George, last_name: Bluth, avatar: https://reqres.in/img/faces/1-image.jpg}
flutter: {id: 2, email: janet.weaver@reqres.in, first_name: Janet, last_name: Weaver, avatar: https://reqres.in/img/faces/2-image.jpg}
flutter: {id: 3, email: emma.wong@reqres.in, first_name: Emma, last_name: Wong, avatar: https://reqres.in/img/faces/3-image.jpg}
flutter: {id: 4, email: eve.holt@reqres.in, first_name: Eve, last_name: Holt, avatar: https://reqres.in/img/faces/4-image.jpg}
flutter: {id: 5, email: charles.morris@reqres.in, first_name: Charles, last_name: Morris, avatar: https://reqres.in/img/faces/5-image.jpg}
flutter: {id: 6, email: tracey.ramos@reqres.in, first_name: Tracey, last_name: Ramos, avatar: https://reqres.in/img/faces/6-image.jpg}

printを**print(user["email"]);**に変更

flutter: george.bluth@reqres.in
flutter: janet.weaver@reqres.in
flutter: emma.wong@reqres.in
flutter: eve.holt@reqres.in
flutter: charles.morris@reqres.in
flutter: tracey.ramos@reqres.in

printを**print(user["first_name"]);**に変更

flutter: George
flutter: Janet
flutter: Emma
flutter: Eve
flutter: Charles
flutter: Tracey

SNS風のUIを作成

main.dart

import 'dart:convert';

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

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.indigo,
      ),
      home: const MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {
  const MyHomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text("Future Builder"),
        ),
        body: ListView.builder(
            itemCount: 5,
            itemBuilder: (context, index) =>
                ListTile(leading: CircleAvatar(),
            title: Text("Name Lengkap"),
            subtitle: Text("email"),
                )));
  }
}

FutureBuilderに書き換える

import 'dart:convert';

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

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.indigo,
      ),
      home: const MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {
  const MyHomePage({Key? key}) : super(key: key);
  // ユーザーのデータをAPIから取得するメソッド
  Future getAllUser() async {
    // ３秒たって読み込む処理
    await Future.delayed(Duration(seconds: 3));
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text("Future Builder"),
        ),
        body: FutureBuilder(
            // ListViewをBuilderでラップしてFutureBuilderに書き換える
            future: getAllUser(),
            builder: (context, snapshot) {
              //, snapshotを追加
              if (snapshot.connectionState == ConnectionState.waiting) {
                // 読み間でいるWidgetを表示
                return Center(
                  child: Text("LOADING ...."),
                );
              } else {
                return ListView.builder(
                    itemCount: 5,
                    itemBuilder: (context, index) => ListTile(
                          leading: CircleAvatar(),
                          title: Text("Name Lengkap"),
                          subtitle: Text("email"),
                        ));
              }
            }));
  }
}

例外処理を追加

import 'dart:convert';

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

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.indigo,
      ),
      home: const MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {
  const MyHomePage({Key? key}) : super(key: key);
  // ユーザーのデータをAPIから取得するメソッド
  Future getAllUser() async {
    try {
      var response = await http.get(Uri.parse("https://reqres.in/api/users"));
      print(response.body);
    } catch (e) {
      print("例外処理が発生");
      print(e);
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text("Future Builder"),
        ),
        body: FutureBuilder(
            // ListViewをBuilderでラップしてFutureBuilderに書き換える
            future: getAllUser(),
            builder: (context, snapshot) {
              //, snapshotを追加
              if (snapshot.connectionState == ConnectionState.waiting) {
                // 読み間でいるWidgetを表示
                return Center(
                  child: Text("LOADING ...."),
                );
              } else {
                return ListView.builder(
                    itemCount: 5,
                    itemBuilder: (context, index) => ListTile(
                          leading: CircleAvatar(),
                          title: Text("Name Lengkap"),
                          subtitle: Text("email"),
                        ));
              }
            }));
  }
}

実行結果

Restarted application in 1,273ms.
Reloaded 1 of 638 libraries in 314ms.
flutter: {"page":1,"per_page":6,"total":12,"total_pages":2,"data":[{"id":1,"email":"george.bluth@reqres.in","first_name":"George","last_name":"Bluth","avatar":"https://reqres.in/img/faces/1-image.jpg"},{"id":2,"email":"janet.weaver@reqres.in","first_name":"Janet","last_name":"Weaver","avatar":"https://reqres.in/img/faces/2-image.jpg"},{"id":3,"email":"emma.wong@reqres.in","first_name":"Emma","last_name":"Wong","avatar":"https://reqres.in/img/faces/3-image.jpg"},{"id":4,"email":"eve.holt@reqres.in","first_name":"Eve","last_name":"Holt","avatar":"https://reqres.in/img/faces/4-image.jpg"},{"id":5,"email":"charles.morris@reqres.in","first_name":"Charles","last_name":"Morris","avatar":"https://reqres.in/img/faces/5-image.jpg"},{"id":6,"email":"tracey.ramos@reqres.in","first_name":"Tracey","last_name":"Ramos","avatar":"https://reqres.in/img/faces/6-image.jpg"}],"support":{"url":"https://reqres.in/#support-heading","text":"To keep ReqRes free, contributions towards server costs are appreciated!"}}

Listを使ってみる

import 'dart:convert';

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

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.indigo,
      ),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {
  // const MyHomePage({Key? key}) : super(key: key);
  // ユーザーというコレクションを定義
  List<Map<String, dynamic>> allUser = [];

  // ユーザーのデータをAPIから取得するメソッド
  Future getAllUser() async {
    try {
      var response = await http.get(Uri.parse("https://reqres.in/api/users"));
      List data = (json.decode(response.body)
          as Map<String, dynamic>)["data"]; // MapでString, dynamic型に変換
      data.forEach((element) {
        allUser.add(element);
      });

      print(allUser);
    } catch (e) {
      print("例外処理が発生");
      print(e);
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text("Future Builder"),
        ),
        body: FutureBuilder(
            // ListViewをBuilderでラップしてFutureBuilderに書き換える
            future: getAllUser(),
            builder: (context, snapshot) {
              //, snapshotを追加
              if (snapshot.connectionState == ConnectionState.waiting) {
                // 読み間でいるWidgetを表示
                return Center(
                  child: Text("LOADING ...."),
                );
              } else {
                return ListView.builder(
                    itemCount: 5,
                    itemBuilder: (context, index) => ListTile(
                          leading: CircleAvatar(),
                          title: Text("Name Lengkap"),
                          subtitle: Text("email"),
                        ));
              }
            }));
  }
}

実行結果

Restarted application in 452ms.
flutter: [{id: 1, email: george.bluth@reqres.in, first_name: George, last_name: Bluth, avatar: https://reqres.in/img/faces/1-image.jpg}, {id: 2, email: janet.weaver@reqres.in, first_name: Janet, last_name: Weaver, avatar: https://reqres.in/img/faces/2-image.jpg}, {id: 3, email: emma.wong@reqres.in, first_name: Emma, last_name: Wong, avatar: https://reqres.in/img/faces/3-image.jpg}, {id: 4, email: eve.holt@reqres.in, first_name: Eve, last_name: Holt, avatar: https://reqres.in/img/faces/4-image.jpg}, {id: 5, email: charles.morris@reqres.in, first_name: Charles, last_name: Morris, avatar: https://reqres.in/img/faces/5-image.jpg}, {id: 6, email: tracey.ramos@reqres.in, first_name: Tracey, last_name: Ramos, avatar: https://reqres.in/img/faces/6-image.jpg}]

import 'dart:convert';

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

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.indigo,
      ),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {
  // const MyHomePage({Key? key}) : super(key: key);
  // ユーザーというコレクションを定義
  List<Map<String, dynamic>> allUser = [];

  // ユーザーのデータをAPIから取得するメソッド
  Future getAllUser() async {
    try {
      var response = await http.get(Uri.parse("https://reqres.in/api/users"));
      List data = (json.decode(response.body)
          as Map<String, dynamic>)["data"]; // MapでString, dynamic型に変換
      data.forEach((element) {
        allUser.add(element);
      });

      print(allUser);
    } catch (e) {
      print("例外処理が発生");
      print(e);
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text("Future Builder"),
        ),
        body: FutureBuilder(
            // ListViewをBuilderでラップしてFutureBuilderに書き換える
            future: getAllUser(),
            builder: (context, snapshot) {
              //, snapshotを追加
              if (snapshot.connectionState == ConnectionState.waiting) {
                // 読み間でいるWidgetを表示
                return Center(
                  child: Text("LOADING ...."),
                );
              } else {
                return ListView.builder(
                    itemCount: allUser.length, // Listのデータを数える
                    itemBuilder: (context, index) => ListTile(
                          leading: CircleAvatar(),
                          // ユーザーのファーストネームとラストネームを取得
                          title: Text("${allUser[index]['first_name']} ${allUser[index]['last_name']}"),
                          subtitle: Text("${allUser[index]['email']}"),
                        ));
              }
            }));
  }
}

List型のallUserから取得したデータを画面に表示

allUserから、画像、名前、メールアドレスを取得

import 'dart:convert';

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

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.indigo,
      ),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {
  // const MyHomePage({Key? key}) : super(key: key);
  // ユーザーというコレクションを定義
  List<Map<String, dynamic>> allUser = [];

  // ユーザーのデータをAPIから取得するメソッド
  Future getAllUser() async {
    try {
      var response = await http.get(Uri.parse("https://reqres.in/api/users"));
      List data = (json.decode(response.body)
          as Map<String, dynamic>)["data"]; // MapでString, dynamic型に変換
      data.forEach((element) {
        allUser.add(element);
      });

      print(allUser);
    } catch (e) {
      print("例外処理が発生");
      print(e);
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text("Future Builder"),
        ),
        body: FutureBuilder(
            // ListViewをBuilderでラップしてFutureBuilderに書き換える
            future: getAllUser(),
            builder: (context, snapshot) {
              //, snapshotを追加
              if (snapshot.connectionState == ConnectionState.waiting) {
                // 読み間でいるWidgetを表示
                return Center(
                  child: Text("LOADING ...."),
                );
              } else {
                return ListView.builder(
                    itemCount: allUser.length, // Listのデータを数える
                    itemBuilder: (context, index) => ListTile(
                          // CircleAvatarはイメージと画像を丸くしてくれる。
                          leading: CircleAvatar(
                            backgroundColor: Colors.grey[300],
                            // コンソールのjsonのデータのavatarを表示
                            backgroundImage: NetworkImage(allUser[index]['avatar']),
                          ),
                          // コンソールのjsonのデータのfirst_nameとlast_nameを表示
                          title: Text("${allUser[index]['first_name']} ${allUser[index]['last_name']}"),
                          // コンソールのjsonのデータのemailを表示
                          subtitle: Text("${allUser[index]['email']}"),
                        ));
              }
            }));
  }
}

モデルを作成してロジック分ける

lib
├── main.dart
└── models
    └── user.dart

models/user.dart

// To parse this JSON data, do
//
//     final userModel = userModelFromJson(jsonString);

import 'dart:convert';

UserModel userModelFromJson(String str) => UserModel.fromJson(json.decode(str));

String userModelToJson(UserModel data) => json.encode(data.toJson());

class UserModel {
  UserModel({
    required this.id,
    required this.email,
    required this.firstName,
    required this.lastName,
    required this.avatar,
  });

  int id;
  String email;
  String firstName;
  String lastName;
  String avatar;

  factory UserModel.fromJson(Map<String, dynamic> json) => UserModel(
        id: json["id"],
        email: json["email"],
        firstName: json["first_name"],
        lastName: json["last_name"],
        avatar: json["avatar"],
      );

  Map<String, dynamic> toJson() => {
        "id": id,
        "email": email,
        "first_name": firstName,
        "last_name": lastName,
        "avatar": avatar,
      };
}

main.dart

import 'dart:convert';

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

import './models/user.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: HomePage(),
    );
  }
}

class HomePage extends StatelessWidget {
  List<UserModel> allUser = [];

  Future getAllUser() async {
    try {
      var response = await http.get(Uri.parse("https://reqres.in/api/users"));
      List data = (json.decode(response.body) as Map<String, dynamic>)["data"];
      data.forEach((element) {
        allUser.add(UserModel.fromJson(element));
      });

      print(allUser);
    } catch (e) {
      //print jika terjadi error
      print("Terjadi kesalahan");
      print(e);
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Future Builder"),
      ),
      body: FutureBuilder(
        future: getAllUser(),
        builder: (context, snapshot) {
          if (snapshot.connectionState == ConnectionState.waiting) {
            return Center(
              child: Text("LOADING ...."),
            );
          } else {
            if (allUser.length == 0) {
              return Center(
                child: Text("TIDAK ADA DATA"),
              );
            }
            return ListView.builder(
              itemCount: allUser.length,
              itemBuilder: (context, index) => ListTile(
                leading: CircleAvatar(
                  backgroundColor: Colors.grey[300],
                  backgroundImage: NetworkImage(allUser[index].avatar),
                ),
                title: Text("${allUser[index].firstName} ${allUser[index].lastName}"),
                subtitle: Text("${allUser[index].email}"),
              ),
            );
          }
        },
      ),
    );
  }
}

問題なく、buildできてます

最後に

今回やってみたUdemyのGetxの講座で紹介されていたFutureBuilderのチュートリアルをやってみて、Web通信のやり方がわかってきた気がします。
Mapとかjson.decodeとか色々出てきました!
やってることは、jsonのデータの型を変換している。
これで、人間でも理解できるデータに変換してくれている。