快速检测数据库是否连接上（与其它主机连接）
在连接主机数据库的时候如果连接不上，会等待很长时间。其实并不是连接数据库慢，而是连接到数据库所在的主机慢。
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1 using System;
2 using System.Collections.Generic;
3 using System.Linq;
4 using System.Text;
5
6 using System.Net.Sockets;
7 using System.Threading;
8
9 namespace Commone
10 {
11 /// <summary>
12 /// 网络端口状态检查类
13 /// </summary>
14 public class NetPortOp
15 {
16 private static bool IsConnectionSuccessful = false;
17 private static Exception socketexception;
18 private static ManualResetEvent TimeoutObject = new ManualResetEvent(false);
19
20 /// <summary>
21 /// 验证连接指定主机的端口
22 /// </summary>
23 /// <param name="host">主机IP或名称</param>
24 /// <param name="port">端口号</param>
25 /// <param name="timeoutMSec">超时时长(毫秒)</param>
26 /// <returns>bool</returns>
27 public static bool ConnValidate(string host, int port, int timeoutMSec)
28 {
29 bool ret = false;
30
31 TimeoutObject.Reset();
32 socketexception = null;
33
34 TcpClient tcpclient = new TcpClient();
35
36 tcpclient.BeginConnect(host, port, new AsyncCallback(CallBackMethod), tcpclient);
37 if (TimeoutObject.WaitOne(timeoutMSec, false))
38 {
39 if (IsConnectionSuccessful)
40 {
41 ret = true;
42 tcpclient.Client.Close();
43 }
44 else
45 {
46 //不用抛出异常，根据ret判断连接成功与否
47 //throw socketexception;
48 }
49 }
50 else
51 {
52 //不用抛出异常，根据ret判断连接成功与否
53 //throw new TimeoutException("TimeOut Exception");
54 }
55
56 tcpclient.Close();
57 return ret;
58 }
59
60 private static void CallBackMethod(IAsyncResult asyncresult)
61 {
62 try
63 {
64 IsConnectionSuccessful = false;
65 TcpClient tcpclient = asyncresult.AsyncState as TcpClient;
66
67 if (tcpclient.Client != null)
68 {
69 tcpclient.EndConnect(asyncresult);
70 IsConnectionSuccessful = true;
71 }
72 }
73 catch (Exception ex)
74 {
75 IsConnectionSuccessful = false;
76 socketexception = ex;
77 }
78 finally
79 {
80 TimeoutObject.Set();
81 }
82 }
83 }
84 }
bool b = Commone.NetPortOp.ConnValidate("192.168.1.119", 1433, 1000);
//连接上返回true，否则返回false。
