Unity C#安卓应用OTG连接Arduino串口通信权限问题求助

Unity开发的Arduino串口通信游戏在Windows、Linux平台可正常运行，但在Android上报错：

Error Unity IOException: Permission denied
Error Unity Rethrow as UnauthorizedAccessException: Access to the path '/dev' is denied.

已尝试添加自定义AndroidManifest.xml并添加权限，但未解决问题：

<?xml version="1.0" encoding="utf-8"?>
<manifest
    xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.unity3d.player"
    xmlns:tools="http://schemas.android.com/tools">
    
    <!--ADDED THESE PERMISSIONS: START-->
    <uses-permission android:name="android.permission.MANAGE_USB" />
    <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
    <uses-feature android:name="android.hardware.usb.host" android:required="true" />
    <!--ADDED THESE PERMISSIONS: END-->

    <application>
        <activity android:name="com.unity3d.player.UnityPlayerActivity" android:theme="@style/UnityThemeSelector"> 
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
            <meta-data android:name="unityplayer.UnityActivity" android:value="true" />
        </activity>
    </application>
</manifest>

现希望无需开发Java/Kotlin插件，找到最简的权限获取及串口通信解决方案。

# 最简解决方案
- **补充权限并动态申请**
  Android 6.0及以上版本需要动态申请危险权限，除Manifest中已添加的权限，需额外添加存储权限（部分设备访问/dev下串口依赖此权限）：
  ```xml
  <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
  <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

同时在C#脚本中动态申请权限，并触发USB设备授权弹窗：

using UnityEngine;
using UnityEngine.Android;

public class USBPermissionHandler : MonoBehaviour
{
    void Start()
    {
        // 申请存储权限
        if (!Permission.HasUserAuthorizedPermission(Permission.ExternalStorageRead))
            Permission.RequestUserPermission(Permission.ExternalStorageRead);
        if (!Permission.HasUserAuthorizedPermission(Permission.ExternalStorageWrite))
            Permission.RequestUserPermission(Permission.ExternalStorageWrite);
        
        // 请求USB设备权限
        RequestArduinoUSBPermission();
    }

    void RequestArduinoUSBPermission()
    {
        AndroidJavaClass unityPlayer = new AndroidJavaClass("com.unity3d.player.UnityPlayer");
        AndroidJavaObject currentActivity = unityPlayer.GetStatic<AndroidJavaObject>("currentActivity");
        AndroidJavaObject usbManager = currentActivity.Call<AndroidJavaObject>("getSystemService", "usb");
        
        // 获取已连接的USB设备列表，筛选Arduino设备（需替换为对应VID/PID）
        AndroidJavaObject deviceList = usbManager.Call<AndroidJavaObject>("getDeviceList");
        AndroidJavaObject iterator = deviceList.Call<AndroidJavaObject>("entrySet").Call<AndroidJavaObject>("iterator");
        
        while (iterator.Call<bool>("hasNext"))
        {
            AndroidJavaObject entry = iterator.Call<AndroidJavaObject>("next");
            AndroidJavaObject device = entry.Call<AndroidJavaObject>("getValue");
            int vid = device.Call<int>("getVendorId");
            int pid = device.Call<int>("getProductId");
            
            // 匹配Arduino Uno的VID/PID，其他型号需修改对应值
            if (vid == 0x2341 && pid == 0x0043)
            {
                AndroidJavaClass usbManagerClass = new AndroidJavaClass("android.hardware.usb.UsbManager");
                string permissionIntentAction = usbManagerClass.GetStatic<string>("ACTION_USB_DEVICE_ATTACHED");
                AndroidJavaObject permissionIntent = new AndroidJavaObject("android.content.Intent", permissionIntentAction);
                permissionIntent.Call<AndroidJavaObject>("putExtra", usbManagerClass.GetStatic<string>("EXTRA_DEVICE"), device);
                currentActivity.Call("startActivityForResult", permissionIntent, 1);
                break;
            }
        }
    }
}

• 跳过/dev遍历，直接指定常见Arduino串口路径
  Android下Arduino串口通常为/dev/ttyUSB0或/dev/ttyACM0，直接尝试连接这两个路径，避免因遍历/dev目录触发权限拒绝：

  using System.IO.Ports;
  
  public class ArduinoSerial : MonoBehaviour
  {
      void ConnectToArduino()
      {
          string[] targetPorts = { "/dev/ttyUSB0", "/dev/ttyACM0" };
          SerialPort activePort = null;
  
          foreach (string port in targetPorts)
          {
              try
              {
                  activePort = new SerialPort(port, 9600);
                  activePort.Open();
                  Debug.Log($"Successfully connected to {port}");
                  break;
              }
              catch (System.Exception e)
              {
                  Debug.Log($"Failed to open {port}: {e.Message}");
                  activePort = null;
              }
          }
  
          // 使用activePort进行后续通信
      }
  }
  

• 使用现成Unity串口插件
  直接导入Unity Asset Store中的成熟串口插件（如Serial Port Utility for Android），这类插件已封装好权限申请、设备检测和通信逻辑，无需编写Java/Kotlin代码，调用插件API即可快速实现功能。

内容的提问来源于stack exchange，提问作者Aarat Satsangi