C#判断网络连接状态

本人最近做c#winform的项目，遇到了判断网络是否正常连接的问题。后来查出了以下几种方法，供大家学习参考。
1.方法一
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Windows.Forms;
using System.Net.Sockets;
using System.Threading;
namespace WindowsFormsApplication1
{
    public partial class Demo : Form
    {
        public Demo()
        {
            InitializeComponent();
        }
        //判断
        private void btpanduan_Click(object sender, EventArgs e)
        {
            //210.192.120.228  163网易
            string ip = this.txtip.Text.ToString();
            int port = Convert .ToInt32( this.txtport.Text.ToString());
            bool a = panduan(ip, port );//135为本机服务端口号
            if (a == true)
            {
                MessageBox.Show("该网络连接正常 ！");
            }
            else
            {
                MessageBox.Show("该网络连接不畅通 ！");
            }
        }
      
      // 异步调用
 
        //判断的方法
        public bool panduan(string ip, int port)
        {
            try
            {
                TcpClient client = new TcpClient(ip, port);
                if (client.Connected)
                {
                    return true;
                }
                else
                {
                    return false;
                }
            }
            catch
            {
                return false;
            }
        }
    }
}
 
2.利用 c# ping类
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Net;
namespace WindowsFormsApplication1
{
    public partial class Demo3 : Form
    {
        public Demo3()
        {
            InitializeComponent();
        }
        System.Net.NetworkInformation.Ping ping = new System.Net.NetworkInformation.Ping();
        System.Net.NetworkInformation.PingReply res;
        //检查网络连接
        private void btcheck_Click(object sender, EventArgs e)
        {

            string url = this.txturl.Text.ToString();
            bool a = check(url);
            if (a == true)
            {
                MessageBox.Show("连接成功！", "提示信息");

            }
            else
            {
                MessageBox.Show("连接失败！", "提示信息");
            }
        }

        public bool check(string url)
        {

            try
            {
                res = ping.Send(url);
                if (res.Status == System.Net.NetworkInformation.IPStatus.Success)
                {
                    return true;
                }
                else
                {
                    return false;
                }
            }
            catch {

                return false;
            }
        }
    }
}
 

using System;using System.Collections.Generic;using System.Text;using System.Net.NetworkInformation;namespace ConsoleApplication1{    class Program    {        public static void Main(string[] args)        {            string url = "www.baidu.com;www.sina.com;www.cnblogs.com;www.google.com;www.163.com;www.csdn.com";            string[] urls = url.Split(new char[] { ';' });            CheckServeStatus(urls);            Console.ReadKey();        }                /// <summary>        /// 检测网络连接状态        /// </summary>        /// <param name="urls"></param>        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");            }            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");                }                else                {                    Console.WriteLine("网络不稳定");                }            }            else            {                Console.WriteLine("网络正常");            }        }        #region 网络检测         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);        /// <summary>        /// 判断本地的连接状态         /// </summary>        /// <returns></returns>        private static bool LocalConnectionStatus()        {            System.Int32 dwFlag = new Int32();            if (!InternetGetConnectedState(ref dwFlag, 0))            {                Console.WriteLine("LocalConnectionStatus--未连网!");                return false;            }            else            {                if ((dwFlag & INTERNET_CONNECTION_MODEM) != 0)                {                    Console.WriteLine("LocalConnectionStatus--采用调制解调器上网。");                    return true;                }                else if ((dwFlag & INTERNET_CONNECTION_LAN) != 0)                {                    Console.WriteLine("LocalConnectionStatus--采用网卡上网。");                    return true;                }            }            return false;        }        /// <summary>        /// Ping命令检测网络是否畅通        /// </summary>        /// <param name="urls">URL数据</param>        /// <param name="errorCount">ping时连接失败个数</param>        /// <returns></returns>        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;        }        #endregion    }}

转自：http://www.2cto.com/kf/201204/128285.html