C#判断网络是否通的代码

[DllImport("wininet.dll")]
        private extern static bool InternetGetConnectedState(out int conn, int val);

        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            int Out;
            if (InternetGetConnectedState(out Out, 0) == true)
            {
                MessageBox.Show("Connected !");
            }
            else
            {
                MessageBox.Show("Not Connected !");
            }
        }