Unity 获取Android 的 USB权限

在Unity中获取Android的USB权限需要使用Android的Java层代码，可以通过Unity的AndroidJavaObject类来调用Java代码实现。以下是获取USB权限的示例代码：

private void GetUsbPermission()
{
    AndroidJavaObject context = new AndroidJavaClass("com.unity3d.player.UnityPlayer").GetStatic<AndroidJavaObject>("currentActivity").Call<AndroidJavaObject>("getApplicationContext");
    AndroidJavaObject usbManager = context.Call<AndroidJavaObject>("getSystemService", "usb");
    AndroidJavaObject usbDevice = GetUsbDevice();

    if (usbDevice != null)
    {
        AndroidJavaObject pendingIntent = AndroidJavaObject("android.app.PendingIntent").CallStatic<AndroidJavaObject>("getBroadcast", context, 0, new AndroidJavaObject("android.content.Intent"), 0);
        AndroidJavaObject intentFilter = AndroidJavaObject("android.content.IntentFilter").CallStatic<AndroidJavaObject>("create", "android.hardware.usb.action.USB_DEVICE_ATTACHED");
        AndroidJavaObject broadcastReceiver = new AndroidJavaObject("android.content.BroadcastReceiver");
        broadcastReceiver.Call("onReceive", context, new AndroidJavaObject("android.content.Intent"));

        context.Call("registerReceiver", broadcastReceiver, intentFilter);
        usbManager.Call("requestPermission", usbDevice, pendingIntent);
    }
}

private AndroidJavaObject GetUsbDevice()
{
    AndroidJavaObject context = new AndroidJavaClass("com.unity3d.player.UnityPlayer").GetStatic<AndroidJavaObject>("currentActivity").Call<AndroidJavaObject>("getApplicationContext");
    AndroidJavaObject usbManager = context.Call<AndroidJavaObject>("getSystemService", "usb");
    AndroidJavaObject usbDevice = null;

    AndroidJavaObject deviceList = usbManager.Call<AndroidJavaObject>("getDeviceList");
    AndroidJavaObject[] deviceArray = AndroidJNIHelper.ConvertFromJNIArray<AndroidJavaObject[]>(deviceList.GetRawObject());

    foreach (AndroidJavaObject device in deviceArray)
    {
        int deviceClass = device.Call<int>("getDeviceClass");
        int deviceSubClass = device.Call<int>("getDeviceSubclass");
        if (deviceClass == 0x02 && deviceSubClass == 0x01)
        {
            usbDevice = device;
            break;
        }
    }

    return usbDevice;
}

这段代码主要包括两个方法：

1. `GetUsbDevice()`：获取连接的USB设备，判断设备的类型是否为USB存储设备。
2. `GetUsbPermission()`：获取USB权限，注册USB设备连接广播，请求USB权限。

需要注意的是，这段代码只是示例代码，具体的实现需要根据实际情况进行修改和优化。