Flutter智能卡读写插件flutter_pcsc的使用

flutter_pcsc 是一个用于在 Windows、macOS 和 Linux 上使用 PCSC 智能卡读卡器的 Flutter 插件。本文将介绍如何使用这个插件，并提供一个完整的示例 demo。

使用说明

前提条件

• 一个 PCSC 智能卡读卡器。
• 在 Linux 系统上，需要安装 pcscd 和 libpcsclite1。

示例代码

以下是一个简单的示例，展示了如何使用 flutter_pcsc 插件与智能卡进行通信：

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

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

class MyApp extends StatelessWidget {
  [@override](/user/override)
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('Plugin example app'),
        ),
        body: SmartCardReader(),
      ),
    );
  }
}

class SmartCardReader extends StatefulWidget {
  [@override](/user/override)
  _SmartCardReaderState createState() => _SmartCardReaderState();
}

class _SmartCardReaderState extends State<SmartCardReader> {
  List<String> messages = [];

  [@override](/user/override)
  void initState() {
    super.initState();
    readCard();
  }

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

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

        card = await Pcsc.cardConnect(ctx, reader, PcscShare.shared, PcscProtocol.any);
        var response = await Pcsc.transmit(card, [0xFF, 0xCA, 0x00, 0x00, 0x00]);
        setState(() {
          messages.add('Response: ${response.toString()}');
        });

        await Pcsc.cardDisconnect(card.hCard, PcscDisposition.resetCard);
      }
    } catch (e) {
      setState(() {
        messages.add('Error: $e');
      });
    } finally {
      await Pcsc.releaseContext(ctx);
    }
  }

  [@override](/user/override)
  Widget build(BuildContext context) {
    return ListView.builder(
      itemCount: messages.length,
      itemBuilder: (context, index) {
        return ListTile(
          title: Text(messages[index]),
        );
      },
    );
  }
}

macOS 应用注意事项

对于 macOS 应用程序，为了能够使用智能卡，需要在 DebugProfile.entitlements 和 Release.entitlements 文件中设置以下权限：

<key>com.apple.security.smartcard</key>
<true/>

如果不正确设置，上下文将无法建立。

完整示例 Demo

以下是一个更完整的示例，包含错误处理和用户界面更新：

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

enum MessageType { info, error }

class Message {
  final String content;
  final MessageType type;

  Message(this.type, this.content);

  static info(String content) => Message(MessageType.info, content);
  static error(String content) => Message(MessageType.error, content);
}

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

  [@override](/user/override)
  _MyAppBodyState createState() => _MyAppBodyState();
}

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

  [@override](/user/override)
  void initState() {
    super.initState();
    getCardSerialNumber();
  }

  Future<void> getCardSerialNumber() async {
    int ctx;
    CardStruct? card;
    try {
      ctx = await Pcsc.establishContext(PcscSCope.user);
      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'));
          });
        }
      }
    } catch (e) {
      messages.add(Message.error(e.toString()));
    } finally {
      if (card != null) {
        try {
          await Pcsc.cardDisconnect(card.hCard, PcscDisposition.resetCard);
        } catch (e) {
          messages.add(Message.error(e.toString()));
        }
      }
      try {
        await Pcsc.releaseContext(ctx);
      } 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(' ');
  }

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

  [@override](/user/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 {
                messages.clear();
                await getCardSerialNumber();
              },
              child: const Text("Try again"),
            ),
          )
        ]),
      )
    ]);
  }
}

void main() {
  runApp(MaterialApp(
    home: Scaffold(
      appBar: AppBar(
        title: const Text('Plugin example app'),
      ),
      body: MyAppBody(),
    ),
  ));
}