test001/lib/plugin/xunfei/audiototext/audiototext.dart

import 'dart:convert';

import 'package:crypto/crypto.dart';
import 'package:demo001/plugin/xunfei/audiototext/result_test.dart';
import 'package:intl/intl.dart';
import 'package:web_socket_channel/web_socket_channel.dart';

typedef ResponseCallback = void Function(
    Xunfei_AudioToText_Result_Text_Item text);

class Xunfei_AudioToText {
  static const int STATUS_FIRST_FRAME = 0;
  static const int STATUS_CONTINUE_FRAME = 1;
  static const int STATUS_LAST_FRAME = 2;

  final String appId;
  final String apiKey;
  final String apiSecret;
  final String host = "iat-api.xfyun.cn";
  final String requestUri = "/v2/iat";
  WebSocketChannel? _channel;

  final ResponseCallback onResponse; // 回调函数类型
  late Xunfei_AudioToText_Result_Text currtext;
  // 静态变量保存唯一实例
  static Xunfei_AudioToText? _instance;
  Xunfei_AudioToText._internal({
    required this.appId,
    required this.apiKey,
    required this.apiSecret,
    required this.onResponse, // 在构造函数中传递回调
  });
  // 工厂构造函数
  factory Xunfei_AudioToText({
    required String appId,
    required String apiKey,
    required String apiSecret,
    required ResponseCallback onResponse,
  }) {
    _instance ??= Xunfei_AudioToText._internal(
      appId: appId,
      apiKey: apiKey,
      apiSecret: apiSecret,
      onResponse: onResponse,
    );
    return _instance!;
  }

  // 创建 WebSocket URL
  String _createUrl() {
    final now = DateTime.now();
    final date =
        DateFormat("EEE, dd MMM yyyy HH:mm:ss 'GMT'").format(now.toUtc());
    final signatureOrigin =
        "host: $host\ndate: $date\nGET $requestUri HTTP/1.1";

    // 使用 HmacUtil 计算 HMAC-SHA256 签名
    final signature = _hmacSha256(apiSecret, signatureOrigin);

    final authorization = base64.encode(utf8.encode(
        "hmac username=\"$apiKey\", algorithm=\"hmac-sha256\", headers=\"host date request-line\", signature=\"$signature\""));

    final queryParams = {
      "host": host,
      "date": date,
      "authorization": authorization,
    };

    final wsUri =
        'ws://$host$requestUri?${Uri(queryParameters: queryParams).query}';
    return wsUri;
  }

  //测试sdk
  Future<void> start() async {
    String wsUrl = _createUrl();
    await _connect(wsUrl);
    await Future.delayed(const Duration(seconds: 3));
    return;
  }

  // 上传音频
  Future<void> pushaudio(Stream<List<int>> audioStream) async {
    int frameSize = 1280; // 每一帧的音频大小
    double interval = 0.04; // 发送音频间隔(单位:s)
    int status = STATUS_FIRST_FRAME; // 音频的状态信息，标识音频是第一帧，还是中间帧、最后一帧
    currtext = Xunfei_AudioToText_Result_Text();
    int index = 0;
    List<int> buffer = [];
    try {
      await for (List<int> frame in audioStream) {
        // 将音频数据添加到 buffer
        buffer.addAll(frame);
        while (buffer.length >= frameSize) {
          List<int> sendFrame = buffer.sublist(0, frameSize);
          buffer = buffer.sublist(frameSize);

          // 判断是否读取到足够的帧
          if (index + frameSize <= buffer.length) {
            frame = buffer.sublist(index, index + frameSize);
            index += frameSize;
          } else {
            frame = buffer.sublist(index);
            index = buffer.length; // 结束
          }

          // 第一帧处理
          if (status == STATUS_FIRST_FRAME) {
            final param = {
              "common": {
                "app_id": appId,
              },
              "business": {
                "language": "zh_cn",
                "domain": "iat",
                "accent": "mandarin",
              },
              "data": {
                "status": status,
                "format": "audio/L16;rate=16000",
                "audio": base64Encode(sendFrame),
                "encoding": "raw",
              }
            };
            String data = json.encode(param);
            _channel?.sink.add(data);
            // print('第一帧已发送...' + data);
            status = STATUS_CONTINUE_FRAME;
          }
          // 中间帧处理
          else if (status == STATUS_CONTINUE_FRAME) {
            final param = {
              "data": {
                "status": status,
                "format": "audio/L16;rate=16000",
                "audio": base64Encode(sendFrame),
                "encoding": "raw",
              }
            };
            String data = json.encode(param);
            _channel?.sink.add(data);
            // print('中间帧已发送...');
          }
          // 最后一帧处理
          else if (status == STATUS_LAST_FRAME) {
            final param = {
              "data": {
                "status": status,
                "format": "audio/L16;rate=16000",
                "audio": base64Encode(sendFrame),
                "encoding": "raw",
              }
            };
            // print('最后一帧已发送...');
            String data = json.encode(param);
            _channel?.sink.add(data);
            break;
          }
          // 模拟音频采样间隔
          await Future.delayed(
              Duration(milliseconds: (interval * 1000).toInt()));
        }
      }
      status = STATUS_LAST_FRAME;
      String data = json.encode({
        "data": {
          "status": status,
          "format": "audio/L16;rate=16000",
          "audio": base64Encode([]),
          "encoding": "raw",
        }
      });
      _channel?.sink.add(data);
    } catch (e) {
      print("push msg: $e");
    }

    print('音频处理完成');
  }

  // 创建WebSocket连接
  Future<void> _connect(String url) async {
    _channel = WebSocketChannel.connect(Uri.parse(url));
    _channel?.stream.listen(
      (message) {
        onMessage(message);
      },
      onError: (error) {
        print('连接失败: $error');
      },
      onDone: () {
        print('WebSocket 连接已关闭');
      },
      cancelOnError: true,
    );
    Future.delayed(const Duration(seconds: 1));
  }

  Future<void> onMessage(String message) async {}

  // 使用SHA-256算法计算HMAC
  String _hmacSha256(String key, String message) {
    var keyBytes = utf8.encode(key); // 将密钥转为字节数组
    var messageBytes = utf8.encode(message); // 将消息转为字节数组
    var hmac = Hmac(sha256, keyBytes); // 创建 HMAC 对象，指定哈希算法和密钥
    var digest = hmac.convert(messageBytes); // 计算消息的哈希
    return base64.encode(digest.bytes); // 返回 base64 编码的哈希值
  }
}