394 lines
13 KiB
Dart
394 lines
13 KiB
Dart
// lib/services/nfc_service.dart
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//
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// NFC 封装服务（包含读取和写入方法，均提供回调与 Future 两种使用方式）
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// 请将此文件放到你的项目中（例如 lib/services/nfc_service.dart）并直接使用。
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import 'dart:async';
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import 'dart:convert';
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import 'dart:io';
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import 'dart:typed_data';
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import 'package:flutter/foundation.dart';
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import 'package:nfc_manager/nfc_manager.dart';
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import 'package:nfc_manager/ndef_record.dart';
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import 'package:nfc_manager/nfc_manager_android.dart';
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import 'package:nfc_manager/nfc_manager_ios.dart';
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import 'package:nfc_manager_ndef/nfc_manager_ndef.dart';
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/// NfcService 单例：提供 NFC 的读取与写入基础能力
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///
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/// - startScanOnceWithCallback(...)：回调式的一次性读取（发现标签即回调）
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/// - readOnceText(...)：Future 式读取，返回解析出的文本（若失败会抛异常）
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/// - writeText(...)：写入文本记录到标签（回调/返回写入结果）
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/// - stopSession()：停止当前会话
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///
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/// 注：iOS 必须在真机测试，并在 Xcode 中打开 NFC 权限；Android 需设备支持 NFC。
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class NfcService {
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NfcService._internal();
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static final NfcService instance = NfcService._internal();
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/// 是否正在进行 NFC 会话（扫描或写入）
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final ValueNotifier<bool> scanning = ValueNotifier(false);
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/// 日志广播流（方便 UI 订阅）
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final StreamController<String> _logController = StreamController.broadcast();
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Stream<String> get logs => _logController.stream;
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/// 检查设备是否支持 NFC
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Future<bool> isAvailable() => NfcManager.instance.isAvailable();
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/// 停止会话（若正在运行）
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Future<void> stopSession() async {
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if (scanning.value) {
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try {
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await NfcManager.instance.stopSession();
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} catch (_) {}
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scanning.value = false;
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}
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}
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// ---------------- 辅助方法 ----------------
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/// bytes -> "AA:BB:CC" 形式的大写十六进制字符串
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String _bytesToHex(Uint8List bytes) {
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return bytes.map((b) => b.toRadixString(16).padLeft(2, '0')).join(':').toUpperCase();
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}
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/// 递归在 Map/List 中查找第一个可用的字节数组 (List<int> / Uint8List)
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List<int>? _findFirstByteArray(dynamic value) {
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if (value == null) return null;
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if (value is Uint8List) return value.toList();
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if (value is List<int>) return value;
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if (value is List) {
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for (var item in value) {
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final found = _findFirstByteArray(item);
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if (found != null) return found;
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}
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return null;
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}
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if (value is Map) {
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for (final entry in value.entries) {
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final found = _findFirstByteArray(entry.value);
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if (found != null) return found;
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}
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}
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return null;
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}
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/// 从 tag（NfcTag / Map）中提取 UID，兼容多种实现
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String extractUidFromTag(dynamic tag) {
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try {
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dynamic raw = tag;
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// 有些实现把数据放 data 字段
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if (tag is Map && tag.containsKey('data')) raw = tag['data'];
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final bytes = _findFirstByteArray(raw);
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if (bytes != null && bytes.isNotEmpty) {
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return _bytesToHex(Uint8List.fromList(bytes));
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}
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// 再尝试一些常见的键名
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if (tag is Map) {
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final possible = ['id', 'identifier', 'Id', 'ID'];
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for (final k in possible) {
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if (tag[k] != null) {
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final b = _findFirstByteArray(tag[k]);
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if (b != null) return _bytesToHex(Uint8List.fromList(b));
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}
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}
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}
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// 最后一招：平台特定 API （如果存在）
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if (Platform.isAndroid) {
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try {
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final nfcA = NfcAAndroid.from(tag);
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if (nfcA != null && nfcA.tag.id != null) return _bytesToHex(Uint8List.fromList(nfcA.tag.id));
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} catch (_) {}
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} else if (Platform.isIOS) {
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try {
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final mifare = MiFareIos.from(tag);
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if (mifare != null && mifare.identifier != null) return _bytesToHex(Uint8List.fromList(mifare.identifier));
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} catch (_) {}
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}
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} catch (e) {
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debugPrint('extractUidFromTag error: $e');
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}
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return 'UNKNOWN';
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}
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/// 从 NDEF record 的 payload 解析文本（Text Record）并返回字符串
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String parseTextFromPayload(Uint8List payload) {
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if (payload.isEmpty) return '';
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final status = payload[0];
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final langLen = status & 0x3F;
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final textBytes = payload.sublist(1 + langLen);
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try {
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return utf8.decode(textBytes);
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} catch (e) {
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return String.fromCharCodes(textBytes);
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}
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}
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String _formatMessageToString(dynamic msg) {
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if (msg == null) return '<empty>';
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try {
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final records = (msg is Map && msg['records'] != null)
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? List<dynamic>.from(msg['records'])
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: (msg is dynamic ? (msg.records as List<dynamic>?) : null);
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if (records == null || records.isEmpty) return '<empty>';
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final sb = StringBuffer();
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for (var i = 0; i < records.length; i++) {
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final r = records[i];
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sb.writeln('Record $i: ${r.toString()}');
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try {
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// 解析 payload
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Uint8List? p;
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if (r is Map && r['payload'] != null) {
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final ptmp = r['payload'];
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if (ptmp is Uint8List) p = ptmp;
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else if (ptmp is List<int>) p = Uint8List.fromList(ptmp);
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} else {
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final pr = (r as dynamic).payload;
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if (pr is Uint8List) p = pr;
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else if (pr is List<int>) p = Uint8List.fromList(pr);
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}
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if (p != null) {
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final txt = parseTextFromPayload(p);
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sb.writeln(' text: $txt');
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}
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} catch (_) {}
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}
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return sb.toString();
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} catch (e) {
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return msg.toString();
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}
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}
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// ---------------- 读取 API ----------------
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/// 回调式的一次性扫描（发现标签后立即回调）
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///
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/// onResult(uid, parsedText, rawMessage) - 当发现标签时回调
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/// onError(error) - 出错时回调
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/// timeout - 超时时间（可选）
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Future<void> startScanOnceWithCallback({
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required void Function(String uid, String parsedText, dynamic rawMessage) onResult,
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void Function(Object error)? onError,
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Duration? timeout,
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}) async {
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final available = await isAvailable();
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if (!available) {
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onError?.call('NFC not available');
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return;
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}
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if (scanning.value) {
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onError?.call('Another session running');
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return;
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}
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scanning.value = true;
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_logController.add('NFC scanning started');
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Timer? timer;
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if (timeout != null) {
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timer = Timer(timeout, () async {
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await stopSession();
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_logController.add('NFC scanning timeout');
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onError?.call('timeout');
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});
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}
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try {
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await NfcManager.instance.startSession(
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onDiscovered: (dynamic tag) async {
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try {
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final uid = extractUidFromTag(tag);
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dynamic rawMsg;
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String parsedText = '';
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// 尝试用 Ndef.from 获取消息
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try {
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final ndef = Ndef.from(tag);
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if (ndef != null) {
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rawMsg = ndef.cachedMessage;
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if (rawMsg != null) {
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// 解析第一条文本记录（若存在）
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if ((rawMsg.records as List).isNotEmpty) {
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final first = rawMsg.records.first;
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final payload = first.payload;
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if (payload is Uint8List) parsedText = parseTextFromPayload(payload);
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else if (payload is List<int>) parsedText = parseTextFromPayload(Uint8List.fromList(payload));
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}
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}
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} else {
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rawMsg = null;
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}
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} catch (_) {
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// 回退：尝试从 tag map 中嗅探 cachedMessage / records
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try {
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if (tag is Map) {
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rawMsg = tag['cachedMessage'] ?? tag['ndef']?['cachedMessage'] ?? tag['message'];
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if (rawMsg != null) {
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final recs = (rawMsg['records'] ?? (rawMsg as dynamic).records) as dynamic;
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if (recs != null && recs is List && recs.isNotEmpty) {
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final r = recs.first;
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final p = (r is Map) ? r['payload'] : (r as dynamic).payload;
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if (p is Uint8List) parsedText = parseTextFromPayload(p);
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else if (p is List<int>) parsedText = parseTextFromPayload(Uint8List.fromList(p));
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}
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}
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}
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} catch (_) {}
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}
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// 回调结果
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onResult(uid, parsedText, rawMsg);
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_logController.add('UID: $uid\nmessage: ${_formatMessageToString(rawMsg)}');
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await stopSession();
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} catch (e) {
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onError?.call(e);
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await stopSession();
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} finally {
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timer?.cancel();
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scanning.value = false;
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}
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},
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// 尽量多协议尝试以提升兼容性
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pollingOptions: {NfcPollingOption.iso14443},
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);
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} catch (e) {
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scanning.value = false;
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timer?.cancel();
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onError?.call(e);
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}
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}
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/// Future 式读取：解析第一条文本记录并返回字符串（格式：'UID\n文本'）
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Future<String> readOnceText({Duration timeout = const Duration(seconds: 10)}) async {
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final completer = Completer<String>();
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await startScanOnceWithCallback(
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onResult: (uid, parsedText, rawMsg) {
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if (parsedText.isEmpty) {
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completer.completeError('No text record found (UID: $uid)');
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} else {
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completer.complete('UID: $uid\n$parsedText');
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}
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},
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onError: (err) {
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if (!completer.isCompleted) completer.completeError(err);
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},
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timeout: timeout,
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);
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return completer.future;
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}
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// ---------------- 写入 API ----------------
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/// 构造 NDEF Text payload（status byte + lang + utf8 bytes）
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Uint8List _buildTextPayload(String text, {String lang = 'en'}) {
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final textBytes = utf8.encode(text);
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final langBytes = utf8.encode(lang);
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final status = langBytes.length & 0x3F;
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final payload = <int>[status, ...langBytes, ...textBytes];
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return Uint8List.fromList(payload);
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}
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/// 写入文本到标签（单条 Text record）
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///
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/// - text: 要写入的文本
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/// - timeout: 超时时间（可选）
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/// - onComplete: 回调 (ok, err)
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///
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/// 返回 true 表示写入成功（同时 onComplete 也会被触发）
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Future<bool> writeText(String text, {Duration? timeout, void Function(bool ok, Object? err)? onComplete}) async {
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final available = await isAvailable();
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if (!available) {
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onComplete?.call(false, 'NFC not available');
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return false;
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}
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if (scanning.value) {
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onComplete?.call(false, 'Another session running');
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return false;
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}
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scanning.value = true;
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Timer? timer;
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if (timeout != null) {
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timer = Timer(timeout, () async {
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await stopSession();
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scanning.value = false;
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onComplete?.call(false, 'timeout');
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});
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}
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bool success = false;
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try {
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await NfcManager.instance.startSession(onDiscovered: (dynamic tag) async {
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try {
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final ndef = Ndef.from(tag);
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if (ndef == null) {
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onComplete?.call(false, 'Tag 不支持 NDEF');
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await stopSession();
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return;
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}
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final payload = _buildTextPayload(text, lang: 'en');
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final record = NdefRecord(
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typeNameFormat: TypeNameFormat.wellKnown,
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type: Uint8List.fromList('T'.codeUnits),
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identifier: Uint8List(0),
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payload: payload,
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);
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final message = NdefMessage(records: [record]);
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await ndef.write(message: message);
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// 取出 UID (优先取 nfca.identifier，如果没有就取顶层 id)
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String? uid;
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if (Platform.isAndroid) {
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try {
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final nfcA = NfcAAndroid.from(tag);
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if (nfcA != null && nfcA.tag.id != null) {
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uid = _bytesToHex(Uint8List.fromList(nfcA.tag.id));
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}
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} catch (_) {}
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} else if (Platform.isIOS) {
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try {
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final mifare = MiFareIos.from(tag);
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if (mifare != null && mifare.identifier != null) {
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uid = _bytesToHex(Uint8List.fromList(mifare.identifier));
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}
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} catch (_) {}
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}
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success = true;
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onComplete?.call(true, uid); // ✅ 把 UID 返回出去
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_logController.add('NFC write success, UID=$uid');
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} catch (e) {
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debugPrint('NFC write error: $e');
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onComplete?.call(false, e);
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} finally {
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await stopSession();
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timer?.cancel();
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scanning.value = false;
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}
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}, pollingOptions: {NfcPollingOption.iso14443});
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} catch (e) {
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scanning.value = false;
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timer?.cancel();
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onComplete?.call(false, e);
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}
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return success;
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}
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/// 释放资源
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void dispose() {
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try {
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_logController.close();
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} catch (_) {}
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}
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}
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