C#判斷網絡

[System.Runtime.InteropServices.DllImport("wininet.dll")]
        private extern static bool InternetGetConnectedState(out int Description, int ReservedValue);

  public static bool IsConnectedToInternet()
        {
            int Desc = 0;
            return InternetGetConnectedState(out Desc, 0);
        }

private void button1_Click(object sender, EventArgs e)
        {

            if (Form1.IsConnectedToInternet())
                MessageBox.Show("OK");
            else
                MessageBox.Show("No");

           
        }