Android 8怎么修改USB默认为MTP

直接上代码
.\frameworks\base\services\usb\java\com\android\server\usb\UsbDeviceManager.java

....
case MSG_SYSTEM_READY:
    updateUsbNotification();
    updateAdbNotification();
    updateUsbFunctions();
    break;
case MSG_BOOT_COMPLETED:
    mBootCompleted = true;
    if (mPendingBootBroadcast) {
        updateUsbStateBroadcastIfNeeded(false);
        mPendingBootBroadcast = false;
    }
    //setEnabledFunctions(null, false, false);删掉这行
    setEnabledFunctions(UsbManager.USB_FUNCTION_MTP, false, false);//加上这行
    if (mCurrentAccessory != null) {
        getCurrentSettings().accessoryAttached(mCurrentAccessory);
    }
    if (mDebuggingManager != null) {
        mDebuggingManager.setAdbEnabled(mAdbEnabled);
    }
    break;
case MSG_USER_SWITCHED: {
.....