Flutter使用usb_serial插件连接USB串口设备遇权限错误求助

问题描述 #

在TvBox H96Max设备上运行基于usb_serial插件的Flutter USB串口交互应用（使用官方示例代码）时，触发UsbManager.openDevice异常，核心错误为：

java.lang.SecurityException: User has not given 10087/com.example.untitled4 permission to access device /dev/bus/usb/001/002

导致无法打开USB串口端口，无法与设备进行数据交互。

原代码 #

import 'dart:async';
import 'dart:typed_data';

import 'package:flutter/material.dart';
import 'package:usb_serial/transaction.dart';
import 'package:usb_serial/usb_serial.dart';

void main() => runApp(MyApp());

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  UsbPort? _port;
  String _status = "Idle";
  List<Widget> _ports = [];
  List<Widget> _serialData = [];

  StreamSubscription<String>? _subscription;
  Transaction<String>? _transaction;
  UsbDevice? _device;

  TextEditingController _textController = TextEditingController();

  Future<bool> _connectTo(device) async {
    _serialData.clear();

    if (_subscription != null) {
      _subscription!.cancel();
      _subscription = null;
    }

    if (_transaction != null) {
      _transaction!.dispose();
      _transaction = null;
    }

    if (_port != null) {
      _port!.close();
      _port = null;
    }

    if (device == null) {
      _device = null;
      setState(() {
        _status = "Disconnected";
      });
      return true;
    }

    _port = await device.create();
    if (await (_port!.open()) != true) {
      setState(() {
        _status = "Failed to open port";
      });
      return false;
    }
    _device = device;

    await _port!.setDTR(true);
    await _port!.setRTS(true);
    await _port!.setPortParameters(115200, UsbPort.DATABITS_8, UsbPort.STOPBITS_1, UsbPort.PARITY_NONE);

    _transaction = Transaction.stringTerminated(_port!.inputStream as Stream<Uint8List>, Uint8List.fromList([13, 10]));

    _subscription = _transaction!.stream.listen((String line) {
      setState(() {
        _serialData.add(Text(line));
        if (_serialData.length > 20) {
          _serialData.removeAt(0);
        }
      });
    });

    setState(() {
      _status = "Connected";
    });
    return true;
  }

  void _getPorts() async {
    _ports = [];
    List<UsbDevice> devices = await UsbSerial.listDevices();
    if (!devices.contains(_device)) {
      _connectTo(null);
    }
    print(devices);

    devices.forEach((device) {
      _ports.add(ListTile(
          leading: Icon(Icons.usb),
          title: Text(device.productName!),
          subtitle: Text(device.manufacturerName!),
          trailing: ElevatedButton(
            child: Text(_device == device ? "Disconnect" : "Connect"),
            onPressed: () {
              _connectTo(_device == device ? null : device).then((res) {
                _getPorts();
              });
            },
          )));
    });

    setState(() {
      print(_ports);
    });
  }

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

    UsbSerial.usbEventStream!.listen((UsbEvent event) {
      _getPorts();
    });

    _getPorts();
  }

  @override
  void dispose() {
    super.dispose();
    _connectTo(null);
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        home: Scaffold(
      appBar: AppBar(
        title: const Text('USB Serial Plugin example app'),
      ),
      body: Center(
          child: Column(children: <Widget>[
        Text(_ports.length > 0 ? "Available Serial Ports" : "No serial devices available", style: Theme.of(context).textTheme.headline6),
        ..._ports,
        Text('Status: $_status\n'),
        Text('info: ${_port.toString()}\n'),
        ListTile(
          title: TextField(
            controller: _textController,
            decoration: InputDecoration(
              border: OutlineInputBorder(),
              labelText: 'Text To Send',
            ),
          ),
          trailing: ElevatedButton(
            child: Text("Send"),
            onPressed: _port == null
                ? null
                : () async {
                    if (_port == null) {
                      return;
                    }
                    String data = _textController.text + "\r\n";
                    await _port!.write(Uint8List.fromList(data.codeUnits));
                    _textController.text = "";
                  },
          ),
        ),
        Text("Result Data", style: Theme.of(context).textTheme.headline6),
        ..._serialData,
      ])),
    ));
  }
}

完整错误信息 #

exception in UsbManager.openDevice
E/UsbManager(19118): java.lang.SecurityException: User has not given 10087/com.example.untitled4 permission to access device /dev/bus/usb/001/002
E/UsbManager(19118):   at android.os.Parcel.createExceptionOrNull(Parcel.java:2426)
E/UsbManager(19118):   at android.os.Parcel.createException(Parcel.java:2410)
E/UsbManager(19118):   at android.os.Parcel.readException(Parcel.java:2393)
E/UsbManager(19118):   at android.os.Parcel.readException(Parcel.java:2335)
E/UsbManager(19118):   at android.hardware.usb.IUsbManager$Stub$Proxy.openDevice(IUsbManager.java:1022)
E/UsbManager(19118):   at android.hardware.usb.UsbManager.openDevice(UsbManager.java:719)
E/UsbManager(19118):   at dev.bessems.usbserial.UsbSerialPlugin.openDevice(UsbSerialPlugin.java:145)
E/UsbManager(19118):   at dev.bessems.usbserial.UsbSerialPlugin.createTyped(UsbSerialPlugin.java:186)
E/UsbManager(19118):   at dev.bessems.usbserial.UsbSerialPlugin.onMethodCall(UsbSerialPlugin.java:288)
E/UsbManager(19118):   at io.flutter.plugin.common.MethodChannel$IncomingMethodCallHandler.onMessage(MethodChannel.java:258)
E/UsbManager(19118):   at io.flutter.embedding.engine.dart.DartMessenger.invokeHandler(DartMessenger.java:295)
E/UsbManager(19118):   at io.flutter.embedding.engine.dart.DartMessenger.lambda$dispatchMessageToQueue$0$io-flutter-embedding-engine-dart-DartMessenger(DartMessenger.java:322)
E/UsbManager(19118):   at io.flutter.embedding.engine.dart.DartMessenger$$ExternalSyntheticLambda0.run(Unknown Source:12)
E/UsbManager(19118):   at android.os.Handler.handleCallback(Handler.java:938)
E/UsbManager(19118):   at android.os.Handler.dispatchMessage(Handler.java:99)
E/UsbManager(19118):   at android.os.Looper.loopOnce(Looper.java:201)
E/UsbManager(19118):   at android.os.Looper.loop(Looper.java:288)
E/UsbManager(19118):   at android.app.ActivityThread.main(ActivityThread.java:7870)
E/UsbManager(19118):   at java.lang.reflect.Method.invoke(Native Method)
E/UsbManager(19118):   at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548)
E/UsbManager(19118):   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1003)
D/CompatibilityChangeReporter(19118): Compat change id reported: 160794467; UID 10087; state: ENABLED
E/flutter (19118): [ERROR:flutter/runtime/dart_vm_initializer.cc(41)] Unhandled Exception: PlatformException(UsbSerialPortAdapter, Failed to acquire USB device., null, null)
E/flutter (19118): #0      StandardMethodCodec.decodeEnvelope (package:flutter/src/services/message_codecs.dart:653:7)
E/flutter (19118): #1      MethodChannel._invokeMethod (package:flutter/src/services/platform_channel.dart:315:18)
E/flutter (19118): <asynchronous suspension>
E/flutter (19118): #2      UsbSerial.createFromDeviceId (package:usb_serial/usb_serial.dart:433:33)
E/flutter (19118): <asynchronous suspension>
E/flutter (19118): #3      UsbDevice.create (package:usb_serial/usb_serial.dart:333:13)
E/flutter (19118): <asynchronous suspension>
E/flutter (19118): #4      _MyAppState.build.<anonymous closure> (package:untitled4/main.dart:175:26)
E/flutter (19118): <asynchronous suspension>

解决方案 #

1. 配置AndroidManifest.xml权限 #

在android/app/src/main/AndroidManifest.xml中添加以下权限和配置：

<!-- USB主机功能声明 -->
<uses-feature android:name="android.hardware.usb.host" />
<!-- USB设备访问权限 -->
<uses-permission android:name="android.permission.USB_PERMISSION" />

<application ...>
    <!-- 监听USB设备连接事件 -->
    <activity ...>
        <intent-filter>
            <action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" />
        </intent-filter>
        <meta-data
            android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED"
            android:resource="@xml/usb_device_filter" />
    </activity>
</application>

若需指定特定USB设备，创建android/app/src/main/res/xml/usb_device_filter.xml文件：

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <usb-device vendor-id="你的设备VID" product-id="你的设备PID" />
</resources>

（设备VID/PID可通过应用设备列表中的device.vid和device.pid获取）

2. 修改代码添加动态权限请求 #

在_connectTo方法中，打开设备前先请求USB权限，修改后的核心代码如下：

Future<bool> _connectTo(device) async {
    // 原有清理代码保持不变

    if (device == null) {
      _device = null;
      setState(() {
        _status = "Disconnected";
      });
      return true;
    }

    // 新增：请求USB设备权限
    bool hasPermission = await UsbSerial.requestPermission(device);
    if (!hasPermission) {
      setState(() {
        _status = "Permission denied";
      });
      return false;
    }

    // 后续打开设备及配置代码保持不变
    _port = await device.create();
    if (await (_port!.open()) != true) {
      setState(() {
        _status = "Failed to open port";
      });
      return false;
    }
    _device = device;

    // 后续串口参数配置、数据流监听代码保持不变
}

3. TvBox设备特殊适配 #

• 进入TvBox系统设置，找到应用权限管理，手动给目标应用开启USB访问权限；
• 若设备有开发者选项，开启USB调试（部分TvBox需此选项才能正常识别USB主机设备）；
• 确保USB串口设备已正确连接，且设备本身支持Android主机模式。

内容的提问来源于stack exchange，提问作者Reem