上传到 /sdcard/Pictures/up 目录

adb push   front.jpg   /sdcard/Pictures/up

广播通知

adb shell am broadcast -a android.intent.action.MEDIA_SCANNER_SCAN_FILE   -d file:///storage/emulated/0/Pictures/up/front.jpg
或者
adb shell am broadcast -a android.intent.action.MEDIA_MOUNTED             -d file:///storage/emulated/0/Pictures/up