Hey there! Let's break down your questions one by one, since you're trying to implement a file-move-to-SD feature without forcing users to root their devices:

1. 权限异常的根源与无Root解决方案 #

The code you referenced likely uses direct filesystem access that requires root privileges—this is because modern Android versions restrict app access to external storage to protect user privacy and security. You don't need root to build this feature! Here's what you should do instead:

• For Android 10 (API 29) and above: Use the Storage Access Framework (SAF) to let users select the target directory on the SD card. Once granted access via the system picker, you can use ContentResolver to copy or move files legally.
• For media files (photos, videos, audio): Use the MediaStore API to manage these files. This lets you move them to SD card directories without root, as long as you've requested the appropriate runtime permissions—like READ_MEDIA_IMAGES (Android 13+) or the legacy READ_EXTERNAL_STORAGE/WRITE_EXTERNAL_STORAGE for older versions.

Avoid direct filesystem paths like /sdcard/ unless you're accessing your app's own private external directory (which only requires basic storage permissions).

2. Is rooting an Android device illegal? #

Rooting itself is not illegal in most regions (such as the US, EU, etc.), but there are critical caveats:

• It almost always voids your device's manufacturer warranty.
• Rooting removes Android's built-in security protections, making the device far more vulnerable to malware, data theft, and system crashes.
• In some cases (like work/school-issued devices), rooting might violate organizational policies. Always double-check local laws and device terms before proceeding.

3. Are there Android devices that come rooted from the factory? #

Yes, but they're rare and targeted at niche users:

• Some small, specialized manufacturers sell devices with pre-rooted ROMs, catering to developers or power users.
• Google's Pixel devices (and other stock Android models) let you unlock the bootloader and root easily, but they don't ship rooted out of the box—you have to do it manually.
• Mainstream brands (Samsung, Xiaomi, etc.) never ship rooted devices, as this violates Google's Compatibility Test Suite (CTS) rules, which are required to access Google Play Services and the Google Play Store.

If you're building an app for the general public, relying on rooted devices is a terrible strategy—only a tiny fraction of users have rooted phones. Stick to official Android APIs for broad compatibility!

内容的提问来源于stack exchange，提问作者user1699790