Flutter去中心化应用插件flutter_dapp的使用

flutter_dapp 是一个用于 Flutter 的运行时应用程序插件。它使用 js_script 来处理逻辑脚本，并通过 xml_layout 来定义用户界面模板。

使用方法

以下是一个完整的示例，展示了如何使用 flutter_dapp 插件来构建一个简单的 Flutter 应用程序：

import 'dart:convert';
import 'dart:typed_data';

import 'package:archive/archive.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter_dapp/extensions/extension.dart';
import 'package:flutter_dapp/extensions/fetch.dart';
import 'package:flutter_dapp/flutter_dapp.dart';
import 'package:js_script/js_script.dart';

// 定义自定义文件系统
class AssetFileSystem extends DappFileSystem {
  final String prefix;
  Map<String, Uint8List> map = {};
  late Future<void> _ready;
  Future<void> get ready => _ready;

  AssetFileSystem({
    required BuildContext context,
    required this.prefix,
  }) {
    _ready = _setup(context);
  }

  Future<void> _setup(BuildContext context) async {
    final manifestJson = await DefaultAssetBundle.of(context).loadString('AssetManifest.json');
    final list = json.decode(manifestJson).keys.where((String key) => key.startsWith(prefix));
    for (String path in list) {
      String str = path.replaceFirst(prefix, '');
      if (str[0] != '/') str = '/' + str;
      var data = await rootBundle.load(path);
      map[str] = data.buffer.asUint8List(data.offsetInBytes, data.lengthInBytes);
    }
  }

  @override
  bool exist(String filename) {
    return map.containsKey(filename);
  }

  @override
  String? read(String filename) {
    var data = map[filename];
    if (data != null) {
      return utf8.decode(data);
    } else {
      return null;
    }
  }

  @override
  Uint8List? readBytes(String filename) {
    return map[filename];
  }
}

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  late Future<LoadData> _future;

  Future<LoadData> _loadData(BuildContext context) async {
    AssetFileSystem fileSystem = AssetFileSystem(
      context: context,
      prefix: 'assets/test'
    );
    await fileSystem.ready;

    JsScript script = JsScript();
    script.dispose();

    return LoadData(
      fileSystem,
      []
    );
  }

  @override
  Widget build(BuildContext context) {
    return FutureBuilder<LoadData>(
      future: _future,
      builder: (context, snapshot) {
        if (snapshot.hasData) {
          var data = snapshot.requireData;
          return DApp(
            entry: '/main',
            fileSystems: [
              data.fileSystem,
            ],
            onInitialize: (script) {
              for (var d in data.extensions) {
                d.attachTo(script);
              }
            },
          );
        } else {
          return Container();
        }
      }
    );
  }

  @override
  void initState() {
    super.initState();
    _future = _loadData(context);
  }
}

解释

AssetFileSystem: 自定义文件系统类，用于从资产目录加载脚本和模板。
LoadData: 包含文件系统和扩展对象的数据模型。
_MyHomePageState: 主页面的状态管理类，负责加载数据并初始化 DApp。
DApp: 核心组件，用于加载主脚本和模板作为入口小部件。

XML 标签说明

以下是 flutter_dapp 支持的一些常用 XML 标签及其属性：

scaffold

<scaffold appBar="PreferredSizeWidget" body="Widget" />

row

<row mainAxisAlignment="MainAxisAlignment" mainAxisSize="MainAxisSize" />

column

<column mainAxisAlignment="MainAxisAlignment" mainAxisSize="MainAxisSize" />

center

<center widthFactor="double" heightFactor="double" />

button

<button onPressed="Void Function" type="DButtonType" />

widget

<widget src="String" data="any" />

appbar

<appbar leading="Widget" actions="List<Widget>" bottom="PreferredSizeWidget" />

list-view

<list-view builder="Widget Function(context, index)" itemCount="int" />

list-item

<list-item leading="Widget" title="Widget" onTap="Void Function" />

img

<img src="String" width="double" height="double" fit="BoxFit" />

callback

<callback function="String" args="List" />

refresh

<refresh loading="bool" onRefresh="Void Function" onLoadMore="Void Function" />

tabs

<tabs scrollable="bool" elevation="double" background="Color">
  <tab title="String" icon="Widget" />
</tabs>

input

<input placeholder="String" text="String" onChange="Void Function(String newText)" />

icon

<icon size="double" color="Color" />

textstyle

<textstyle color="Color" size="double" />

stack

<stack alignment="Alignment" fit="StackFit" clip="Clip" />

view

<view width="double" height="double" color="Color" animate="bool" duration="Duration" />

border

<border top="BorderSide" right="BorderSide" bottom="BorderSide" left="BorderSide" />

linear-gradient

<linear-gradient begin="Alignment" end="Alignment" colors="List<Color>" stops="List<double>" />

slivers

<slivers direction="Axis" reverse="bool">
  <sliver-list-view builder="Widget Function(context, index)" itemCount="int" />
</slivers>

grid-view

<grid-view builder="IndexedWidgetBuilder" itemCount="int" crossAxisCount="int" childAspectRatio="double" />

更多关于Flutter去中心化应用插件flutter_dapp的使用的实战教程也可以访问 https://www.itying.com/category-92-b0.html

htzhanglong 1楼

更多关于Flutter去中心化应用插件flutter_dapp的使用的实战系列教程也可以访问 https://www.itying.com/category-92-b0.html

flutter_dapp 是一个用于在 Flutter 应用中集成去中心化应用（DApp）的插件。它允许开发者与以太坊区块链进行交互，包括发送交易、调用智能合约、查询区块链数据等。以下是如何使用 flutter_dapp 插件的基本步骤：

1. 添加依赖

首先，在 pubspec.yaml 文件中添加 flutter_dapp 依赖：

dependencies:
  flutter:
    sdk: flutter
  flutter_dapp: ^0.1.0  # 请使用最新版本

然后运行 flutter pub get 来安装依赖。

2. 初始化 `flutter_dapp`

在你的 Flutter 应用中，首先需要初始化 flutter_dapp。通常，你可以在 main.dart 文件中进行初始化：

import 'package:flutter/material.dart';
import 'package:flutter_dapp/flutter_dapp.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await FlutterDapp.initialize();
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter DApp',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(),
    );
  }
}

3. 连接到以太坊网络

在应用中，你可以使用 flutter_dapp 连接到以太坊网络。以下是一个简单的示例，展示如何连接到以太坊主网：

import 'package:flutter/material.dart';
import 'package:flutter_dapp/flutter_dapp.dart';

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  late EthereumClient client;

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

  Future<void> connectToEthereum() async {
    client = await FlutterDapp.connectToEthereum(
      rpcUrl: 'https://mainnet.infura.io/v3/YOUR_INFURA_PROJECT_ID',
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Flutter DApp'),
      ),
      body: Center(
        child: Text('Connected to Ethereum Network'),
      ),
    );
  }
}

4. 与智能合约交互

你可以使用 flutter_dapp 与智能合约进行交互。以下是一个简单的示例，展示如何调用智能合约的方法：

import 'package:flutter/material.dart';
import 'package:flutter_dapp/flutter_dapp.dart';

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  late EthereumClient client;
  late Contract contract;

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

  Future<void> connectToEthereum() async {
    client = await FlutterDapp.connectToEthereum(
      rpcUrl: 'https://mainnet.infura.io/v3/YOUR_INFURA_PROJECT_ID',
    );

    contract = await client.getContract(
      address: '0xYourContractAddress',
      abi: 'YourContractABI',
    );
  }

  Future<void> callContractMethod() async {
    var result = await contract.call('yourMethodName', [arg1, arg2]);
    print(result);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Flutter DApp'),
      ),
      body: Center(
        child: ElevatedButton(
          onPressed: callContractMethod,
          child: Text('Call Contract Method'),
        ),
      ),
    );
  }
}

5. 发送交易

你还可以使用 flutter_dapp 发送交易。以下是一个简单的示例，展示如何发送以太币：

import 'package:flutter/material.dart';
import 'package:flutter_dapp/flutter_dapp.dart';

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  late EthereumClient client;

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

  Future<void> connectToEthereum() async {
    client = await FlutterDapp.connectToEthereum(
      rpcUrl: 'https://mainnet.infura.io/v3/YOUR_INFURA_PROJECT_ID',
    );
  }

  Future<void> sendTransaction() async {
    var transaction = await client.sendTransaction(
      to: '0xRecipientAddress',
      value: EtherAmount.fromUnitAndValue(EtherUnit.ether, 1),
    );
    print(transaction);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Flutter DApp'),
      ),
      body: Center(
        child: ElevatedButton(
          onPressed: sendTransaction,
          child: Text('Send Transaction'),
        ),
      ),
    );
  }
}

6. 处理钱包和私钥

flutter_dapp 还支持处理钱包和私钥。你可以使用它来创建钱包、导入私钥、签名交易等。

import 'package:flutter/material.dart';
import 'package:flutter_dapp/flutter_dapp.dart';

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  late Wallet wallet;

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

  Future<void> createWallet() async {
    wallet = await FlutterDapp.createWallet();
    print('Wallet Address: ${wallet.address}');
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Flutter DApp'),
      ),
      body: Center(
        child: Text('Wallet Created'),
      ),
    );
  }
}

7. 处理错误和异常

在使用 flutter_dapp 时，务必处理可能出现的错误和异常。你可以使用 try-catch 块来捕获和处理异常。

try {
  var result = await contract.call('yourMethodName', [arg1, arg2]);
  print(result);
} catch (e) {
  print('Error: $e');
}

Flutter去中心化应用插件flutter_dapp的使用

Flutter去中心化应用插件flutter_dapp的使用

使用方法

解释

XML 标签说明

scaffold

row

column

center

button

widget

appbar

list-view

list-item

img

callback

refresh

tabs

input

icon

textstyle

stack

view

border

linear-gradient

slivers

grid-view

1. 添加依赖

2. 初始化 flutter_dapp

3. 连接到以太坊网络

4. 与智能合约交互

5. 发送交易

6. 处理钱包和私钥

7. 处理错误和异常

2. 初始化 `flutter_dapp`