C#编程小实例（一）（Check internet connectivity and ping a host in C# 用C#查看互联网连接以及ping一个主机）（未看）

This is a snippet that has 4 methods, 1 enum and 1 Win32 API that will first check to make sure the "pinger" has an actual connection, then it sends the ping 4 times to the pinged host and returns the results

 

Language: C#

Last Modified: November 10, 2008

Instructions: Need references to the following Namespaces:

using System.Runtime.InteropServices;
using System.Net;
using System.Net.NetworkInformation;
using System.Net.Sockets;

Snippet

1. //Namespace References
2. using System;
3. using System.Runtime.InteropServices;
4. using System.Net;
5. using System.Net.NetworkInformation;
6. using System.Net.Sockets;
7.  
8. public static class CheckInternetConnectivity
9. {
10.     [DllImport("wininet", CharSet = CharSet.Auto)]
11.     static extern bool InternetGetConnectedState(ref ConnectionStatusEnum flags, int dw);
12.  
13.     /// <summary>
14.     /// enum to hold the possible connection states
15.     /// </summary>
16.     [Flags]
17.     enum ConnectionStatusEnum : int
18.     {
19.         INTERNET_CONNECTION_MODEM = 0x1,
20.         INTERNET_CONNECTION_LAN = 0x2,
21.         INTERNET_CONNECTION_PROXY = 0x4,
22.         INTERNET_RAS_INSTALLED = 0x10,
23.         INTERNET_CONNECTION_OFFLINE = 0x20,
24.         INTERNET_CONNECTION_CONFIGURED = 0x40
25.     }
26.  
27.     /// <summary>
28.     /// method to check the status of the pinging machines internet connection
29.     /// </summary>
30.     /// <returns></returns>
31.     private static bool HasConnection()
32.     {
33.         //instance of out ConnectionStatusEnum
34.         ConnectionStatusEnum state = 0;
35.  
36.         //call the API
37.         InternetGetConnectedState(ref state, 0);
38.  
39.         //check the status, if not offline and the returned state
40.         //isnt 0 then we have a connection
41.         if (((int)ConnectionStatusEnum.INTERNET_CONNECTION_OFFLINE & (int)state) != 0)
42.         {
43.             //return true, we have a connection
44.             return false;
45.         }
46.         //return false, no connection available
47.         return true;
48.     }
49.  
50.     /// <summary>
51.     /// method for retrieving the IP address from the host provided
52.     /// </summary>
53.     /// <param name="host">the host we need the address for</param>
54.     /// <returns></returns>
55.     private static IPAddress GetIpFromHost(ref string host)
56.     {
57.         string returnMessage = string.Empty;
58.         //IPAddress instance for holding the returned host
59.         IPAddress address = null;
60.  
61.         //wrap the attempt in a try..catch to capture
62.         //any exceptions that may occur
63.         try
64.         {
65.             //get the host IP from the name provided
66.             address = Dns.GetHostEntry(host).AddressList[0];
67.         }
68.         catch (SocketException ex)
69.         {
70.             //some DNS error happened, return the message
71.             returnMessage = string.Format("DNS Error: {0}", ex.Message);
72.         }
73.         return address;
74.     }
75.  
76.     /// <summary>
77.     /// method to check the ping status of a provided host
78.     /// </summary>
79.     /// <param name="addr">the host we need to ping</param>
80.     /// <returns></returns>
81.     public static string CheckSiteStatus(string host)
82.     {
83.         //string to hold our return messge
84.         string returnMessage = string.Empty;
85.  
86.         //IPAddress instance for holding the returned host
87.         IPAddress address = GetIpFromHost(ref host);
88.  
89.         //set the ping options, TTL 128
90.         PingOptions options = new PingOptions(128, true);
91.  
92.         //create a new ping instance
93.         Ping ping = new Ping();
94.  
95.         //32 byte buffer
96.         byte[] data = new byte[32];
97.  
98.         //first make sure we actually have an internet connection
99.         if (HasConnection())
100.         {
101.             //here we will ping the host 4 times (standard)
102.             for (int i = 0; i < 4; i++)
103.             {
104.                 try
105.                 {
106.                     //send the ping 4 times to the host and record the returned data
107.                     PingReply reply = ping.Send(address, 1000, data, options);
108.  
109.                     //make sure we dont have a null reply
110.                     if (!(reply == null))
111.                     {
112.                         switch (reply.Status)
113.                         {
114.                             case IPStatus.Success:
115.                                 returnMessage = string.Format("Reply from {0}: bytes={1} time={2}ms TTL={3}", reply.Address, reply.Buffer.Length, reply.RoundtripTime, reply.Options.Ttl);
116.                                 break;
117.                             case IPStatus.TimedOut:
118.                                 returnMessage = "Connection has timed out...";
119.                                 break;
120.                             default:
121.                                 returnMessage = string.Format("Ping failed: {0}", reply.Status.ToString());
122.                                 break;
123.                         }
124.                     }
125.                     else
126.                         returnMessage = "Connection failed for an unknown reason...";
127.                 }
128.                 catch (PingException ex)
129.                 {
130.                     returnMessage = string.Format("Connection Error: {0}", ex.Message);
131.                 }
132.                 catch (SocketException ex)
133.                 {
134.                     returnMessage = string.Format("Connection Error: {0}", ex.Message);
135.                 }
136.             }
137.         }
138.         else
139.             returnMessage = "No Internet connection found...";
140.  
141.         //return the message
142.         return returnMessage;
143.     }
144. }