求助：Android Kiosk模式下如何让Google FILES应用访问U盘？

我基于Advanced Android Kiosk Mode模板做了定制，实现了两个核心功能：

• 允许Kiosk应用启动其他应用
• 支持用户从U盘选择.apk文件完成应用更新

为选择.apk文件，Kiosk应用会调用设备预装的Google FILES应用，但在Kiosk模式下，FILES应用无法识别U盘。

已尝试的修改 #

我修改了Kiosk应用中的GetRestrictions函数，移除了DISALLOW_MOUNT_PHYSICAL_MEDIA限制，但问题依然存在：

function TKioskApplication.GetRestrictions: TArrayOfJStrings;
begin
//  SetLength(Result, 6);
  SetLength(Result, 5);
  Result[0] := StringToJString(TJUserManagerDISALLOW_FACTORY_RESET);
  Result[1] := StringToJString(TJUserManagerDISALLOW_SAFE_BOOT);
//  Result[2] := StringToJString(TJUserManagerDISALLOW_MOUNT_PHYSICAL_MEDIA);
  Result[2] := StringToJString(TJUserManagerDISALLOW_ADJUST_VOLUME);
  Result[3] := StringToJString(TJUserManagerDISALLOW_ADD_USER);
  Result[4] := StringToJString(TJUserManagerDISALLOW_CREATE_WINDOWS);
end;

Android日志分析 #

连接U盘时的系统日志显示，设备已识别到U盘硬件，但最终U盘状态为state=UNMOUNTED，无法被访问：

2-1 new high-speed USB device number 4 using ehci-platform
2-1 New USB device found, idVendor=0718, idProduct=0619, bcdDevice= 1.00
2-1 New USB device strings: Mfr=1, Product=2, SerialNumber=3
2-1 Product: Trans-It Drive
2-1 Manufacturer: TDKMedia
2-1 SerialNumber: 07BA0703BE242FA7
2-1: 1.0: USB Mass Storage device detected
host0: usb-storage 2-1:1.0
uid=1000(system) android.fg identical 129 lines
Close system dialogs
USB device attached: vidpid 0718:0619 mfg/product/ver/serial TDKMedia/Trans-It Drive/1.00/07BA0703BE242FA7 hasAudio/HID/Storage: false/false/true
Close system dialogs
uid=10117(com.android.systemui) identical 130 lines
NotificationShadeWindow: com.android.systemui.statusbar.phone.NotificationShadeWindowView{dbf45aa I.E...... ......ID 0,0-1280,800} canPanelBeCollapsed(): false
1 configs
Added device UsbDevice[mName=/dev/bus/usb/002/004,mVendorId=1816,mProductId=1561,mClass=0,mSubclass=0,mProtocol=0,mManufacturerName=TDKMedia,mProductName=Trans-It Drive,mVersion=1.00,mSerialNumberReader=com.android.server.usb.UsbSerialReader@6898cac, mHasAudioPlayback=false, mHasAudioCapture=false, mHasMidi=false, mHasVideoCapture=false, mHasVideoPlayback=false, mConfigurations=[
UsbConfiguration[mId=1,mName=null,mAttributes=128,mMaxPower=100,mInterfaces=[
UsbInterface[mId=0,mAlternateSetting=0,mName=null,mClass=8,mSubclass=6,mProtocol=80,mEndpoints=[
UsbEndpoint[mAddress=129,mAttributes=2,mMaxPacketSize=512,mInterval=0]
UsbEndpoint[mAddress=2,mAttributes=2,mMaxPacketSize=512,mInterval=0]]]]
Clear notification
Close system dialogs
NotificationShadeWindow: com.android.systemui.statusbar.phone.NotificationShadeWindowView{dbf45aa I.E...... ......ID 0,0-1280,800} canPanelBeCollapsed(): false
0 0:0:0: Direct-Access TDKMedia Trans-It Drive PMAP PQ: 0 ANSI: 4
0 0:0:0: Attached scsi generic sg0 type 0
uid=10117(com.android.systemui) identical 26 lines
NotificationShadeWindow: com.android.systemui.statusbar.phone.NotificationShadeWindowView{dbf45aa I.E...... ......ID 0,0-1280,800} canPanelBeCollapsed(): false
Updating roots due to change on user 0at content://com.android.externalstorage.documents
NotificationShadeWindow: com.android.systemui.statusbar.phone.NotificationShadeWindowView{dbf45aa I.E...... ......ID 0,0-1280,800} canPanelBeCollapsed(): false
0 0:0:0: [sda] 7555072 512-byte logical blocks: (3.87 GB/3.60 GiB)
0 0:0:0: [sda] Write Protect is off
0 0:0:0: [sda] Mode Sense: 23 00 00 00
0 0:0:0: [sda] No Caching mode page found
0 0:0:0: [sda] Assuming drive cache: write through
sda1
uid=1000(system) android.fg identical 46 lines
Close system dialogs
/system/bin/sgdisk
--android-dump
/dev/block/vold/disk:8,0
0 0:0:0: [sda] Attached SCSI removable disk
DISK mbr
PART 1 c
uid=10117(com.android.systemui) identical 18 lines
NotificationShadeWindow: com.android.systemui.statusbar.phone.NotificationShadeWindowView{dbf45aa I.E...... ......ID 0,0-1280,800} canPanelBeCollapsed(): false
-----for all public volume is visible-----
Ignoring mount public:8,1 due to policy
Notifying volume state changed for session with id: public:8,1
No session found for sessionId: public:8,1
After updating volumes, found 1 active roots
Notifying about public volume: VolumeInfo{public:8,1}:
type=PUBLIC diskId=disk:8,0 partGuid= mountFlags=VISIBLE mountUserId=0
state=UNMOUNTED
fsType=null fsUuid=null fsLabel=null
path=null internalPath=null
After updating volumes, found 1 active roots
Close system dialogs
NotificationShadeWindow: com.android.systemui.statusbar.phone.NotificationShadeWindowView{dbf45aa I.E...... ......ID 0,0-1280,800} canPanelBeCollapsed(): false
uid=10117(com.android.systemui) identical 162 lines
NotificationShadeWindow: com.android.systemui.statusbar.phone.NotificationShadeWindowView{dbf45aa I.E...... ......ID 0,0-1280,800} canPanelBeCollapsed(): false
Updating roots due to change on user 0at content://com.android.externalstorage.documents
Updating roots due to change on user 0at content://com.android.externalstorage.documents
NotificationShadeWindow: com.android.systemui.statusbar.phone.NotificationShadeWindowView{dbf45aa I.E...... ......ID 0,0-1280,800} canPanelBeCollapsed(): false

环境信息 #

• 目标设备：Android 11
• 开发环境：Delphi 12.2 + Patch 2

非Kiosk模式下，U盘可正常被FILES应用识别并访问。

内容的提问来源于stack exchange，提问作者steve.b