使用flutter开发windows桌面软件读取ACR22U设备的nfc卡片id，5分钟搞定demo

最近有个需求，要使用acr122u读卡器插入电脑usb口，然后读取nfc卡片的id，并和用户账号绑定，调研了很多方式，之前使用rust实现过一次，还有go实现过一次，然后使用electron的时候遇到安装pcsc-lite失败的问题，一直不能成功解决，所以就考虑使用flutter试试，结果成功了，哈哈哈，在这里记录一下过程。

安装依赖

我使用的依赖库是：flutter_pcsc | Flutter Package

所以按照官方提示直接添加依赖项到pubspec.yaml中：

flutter_pcsc: ^0.0.4

然后使用 pub get 命令获取安装一下依赖：

写代码读取nfc

直接复制官方的demo案例代码：

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

import 'package:flutter_pcsc/flutter_pcsc.dart';

void main() {
  MyApp? myApp;

  runZonedGuarded(() async {
    WidgetsFlutterBinding.ensureInitialized();
    FlutterError.onError = (FlutterErrorDetails details) {
      FlutterError.dumpErrorToConsole(details);
      myApp?.addError(details.toString());
    };

    runApp(myApp = MyApp());
  }, (Object error, StackTrace stack) {
    myApp?.addError(error.toString());
  });
}

class MyApp extends StatelessWidget {
  final GlobalKey<_MyAppBodyState> _myAppKey = GlobalKey();

  MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
          appBar: AppBar(
            title: const Text('Plugin example app'),
          ),
          body: MyAppBody(key: _myAppKey)),
    );
  }

  void addError(String msg) {
    _myAppKey.currentState?.messages.add(Message.error(msg));
  }
}

class MyAppBody extends StatefulWidget {
  const MyAppBody({required Key key}) : super(key: key);

  @override
  _MyAppBodyState createState() {
    return _MyAppBodyState();
  }
}

enum MessageType { info, error }

class Message {
  final String content;
  final MessageType type;
  Message(this.type, this.content);

  static info(String content) {
    return Message(MessageType.info, content);
  }

  static error(String content) {
    return Message(MessageType.error, content);
  }
}

class _MyAppBodyState extends State<MyAppBody> {
  static const List<int> getCardSerialNumberCommand = [
    0xFF,
    0xCA,
    0x00,
    0x00,
    0x00
  ];
  final ScrollController _scrollController = ScrollController();

  final List<Message> messages = [];

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

  Future<void> getCardSerialNumber() async {
    int ctx = await Pcsc.establishContext(PcscSCope.user);
    CardStruct? card;
    try {
      List<String> readers = await Pcsc.listReaders(ctx);

      if (readers.isEmpty) {
        messages.add(Message.error('Could not detect any reader'));
      } else {
        String reader = readers[0];
        setState(() {
          messages.add(Message.info('Using reader: $reader'));
        });

        card = await Pcsc.cardConnect(
            ctx, reader, PcscShare.shared, PcscProtocol.any);
        var response = await Pcsc.transmit(card, getCardSerialNumberCommand);
        var sw = response.sublist(response.length - 2);
        var sn = response.sublist(0, response.length - 2);

        if (sw[0] != 0x90 || sw[1] != 0x00) {
          setState(() {
            messages
                .add(Message.error('Card returned an error: ${hexDump(sw)}'));
          });
        } else {
          setState(() {
            messages.add(Message.info('Card Serial Number is: ${hexDump(sn)}'));
            messages.add(Message.info('Done'));
          });
        }
      }
    } finally {
      if (card != null) {
        try {
          await Pcsc.cardDisconnect(card.hCard, PcscDisposition.resetCard);
        } on Exception catch (e) {
          messages.add(Message.error(e.toString()));
        }
      }
      try {
        await Pcsc.releaseContext(ctx);
      } on Exception catch (e) {
        messages.add(Message.error(e.toString()));
      }
    }
  }

  static String hexDump(List<int> csn) {
    return csn
        .map((i) => i.toRadixString(16).padLeft(2, '0').toUpperCase())
        .join(' ');
  }

  _scrollToBottom() {
    _scrollController.jumpTo(_scrollController.position.maxScrollExtent);
  }

  @override
  Widget build(BuildContext context) {
    TextStyle errorStyle = const TextStyle(color: Colors.red);
    WidgetsBinding.instance?.addPostFrameCallback((_) => _scrollToBottom());
    return Row(crossAxisAlignment: CrossAxisAlignment.start, children: [
      Expanded(
          child: Column(children: [
        Expanded(
            child: ListView(
                controller: _scrollController,
                children: messages
                    .map((e) => Text(e.content,
                        style: e.type == MessageType.error ? errorStyle : null))
                    .toList())),
        Container(
            margin: const EdgeInsets.all(10),
            child: ElevatedButton(
                onPressed: () async {
                  await tryAgain();
                },
                child: const Text("Try again")))
      ]))
    ]);
  }

  tryAgain() async {
    messages.clear();
    await getCardSerialNumber();
  }
}

运行后应该是啥都没有的空页面，这时候插上acr122u设备，并放上nfc卡片：

然后点击下面的 Try again 按钮：就成功了 

打包测试

打包成msix或者exe程序测试一下，如果你想打包成msix安装包，可以看我的另外一篇文章：https://xiaoshen.blog.csdn.net/article/details/135308360

执行命令打包：

# 打包成exe程序

flutter build


# 如果你想打包成msix程序，需要安装msix依赖

dart run msix:create

 看到成功后就可以了

然后到项目里面这个文件夹下面，找到这个安装包，安装后运行一下试试：完美撒花