判断网络状态

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Net.NetworkInformation;

namespace TestConnectionStatus
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        private string url;
        string[] urls;
        private void Form1_Load(object sender, EventArgs e)
        {
            url = "www.baidu.com;www.sina.com;www.cnblogs.com;www.google.com;www.163.com;www.csdn.com";
            urls = url.Split(new char[] { ';' });
            CheckServeStatus(urls);
        }

        private const int INTERNET_CONNECTION_MODEM = 1;
        private const int INTERNET_CONNECTION_LAN = 2;

        [System.Runtime.InteropServices.DllImport("winInet.dll")]
        private static extern bool InternetGetConnectedState(ref int dwFlag, int dwReserved);

        public static void CheckServeStatus(string[] urls)
        {
            int errCount = 0;//ping时连接失败个数

            if (!LocalConnectionStatus())
            {
                Console.WriteLine("网络异常~无连接");
                if (MessageBox.Show("网络异常~无连接", "退出", MessageBoxButtons.OKCancel, MessageBoxIcon.Question) == DialogResult.OK)
                {
                }
            }
            else if (!MyPing(urls, out errCount))
            {
                if ((double)errCount / urls.Length >= 0.3)
                {
                    Console.WriteLine("网络异常~连接多次无响应");
                    if (MessageBox.Show("网络异常~连接多次无响应", "退出", MessageBoxButtons.OKCancel, MessageBoxIcon.Question) == DialogResult.OK)
                    {
                    }
                }
                else
                {
                    Console.WriteLine("网络不稳定");
                    if (MessageBox.Show("网络不稳定", "退出", MessageBoxButtons.OKCancel, MessageBoxIcon.Question) == DialogResult.OK)
                    {
                    }
                }
            }
            else
            {
                Console.WriteLine("网络正常");
                if (MessageBox.Show("网络正常", "退出", MessageBoxButtons.OKCancel, MessageBoxIcon.Question) == DialogResult.OK)
                {
                }
            }
        }
        private static bool LocalConnectionStatus()
        {
            System.Int32 dwFlag = new Int32();
            if (!InternetGetConnectedState(ref dwFlag, 0))
            {
                Console.WriteLine("LocalConnectionStatus--未连网!");
                if (MessageBox.Show("未连网", "退出", MessageBoxButtons.OKCancel, MessageBoxIcon.Question) == DialogResult.OK)
                {
                }
                return false;
            }
            else
            {
                if ((dwFlag & INTERNET_CONNECTION_MODEM) != 0)
                {
                    Console.WriteLine("LocalConnectionStatus--采用调制解调器上网。");
                    if (MessageBox.Show("采用调制解调器上网", "退出", MessageBoxButtons.OKCancel, MessageBoxIcon.Question) == DialogResult.OK)
                    {
                    }
                    return true;
                }
                else if ((dwFlag & INTERNET_CONNECTION_LAN) != 0)
                {
                    Console.WriteLine("LocalConnectionStatus--采用网卡上网。");
                    if (MessageBox.Show("采用网卡上网", "退出", MessageBoxButtons.OKCancel, MessageBoxIcon.Question) == DialogResult.OK)
                    {
                    }
                    return true;
                }
            }
            return false;
        }
        public static bool MyPing(string[] urls, out int errorCount)
        {
            bool isconn = true;
            Ping ping = new Ping();
            errorCount = 0;
            try
            {
                PingReply pr;
                for (int i = 0; i < urls.Length; i++)
                {
                    pr = ping.Send(urls[i]);
                    if (pr.Status != IPStatus.Success)
                    {
                        isconn = false;
                        errorCount++;
                    }
                    Console.WriteLine("Ping " + urls[i] + "    " + pr.Status.ToString());
                }
            }
            catch
            {
                isconn = false;
                errorCount = urls.Length;
            }
            //if (errorCount > 0 && errorCount < 3)
            //  isconn = true;
            return isconn;
        }

    }
}