怎样判断当前设备是否连接了VPN？

public static async isVPN(): Promise<boolean> { 
  try { 
  const defaultNetHandle = await netConnection.getDefaultNet() 
  const capabilities = await netConnection.getNetCapabilities(defaultNetHandle) 
  const noVpnCap: netConnection.NetCap | undefined = capabilities.networkCap?.find((elem: netConnection.NetCap) => { 
    return elem == netConnection.NetCap.NET_CAPABILITY_NOT_VPN 
  }) 
 
  return !noVpnCap 
} catch(error) { 
  logger.e("invoke isVPN failed.", error) 
  return false 
} 
}