using System;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace TECH.AdoClientLib
{
   public class SqlLocator
   {
      [DllImport("odbc32.dll")]
      private static extern short SQLAllocHandle(short hType, IntPtr inputHandle, out IntPtr outputHandle);
      [DllImport("odbc32.dll")]
      private static extern short SQLSetEnvAttr(IntPtr henv, int attribute, IntPtr valuePtr, int strLength);
      [DllImport("odbc32.dll")]
      private static extern short SQLFreeHandle(short hType, IntPtr handle);
      [DllImport("odbc32.dll", CharSet = CharSet.Ansi)]
      private static extern short SQLBrowseConnect(IntPtr hconn, StringBuilder inString, short inStringLength, StringBuilder outString, short outStringLength, out short outLengthNeeded);
      
      private const short SQL_HANDLE_ENV = 1;
      private const short SQL_HANDLE_DBC = 2;
      private const int SQL_ATTR_ODBC_VERSION = 200;
      private const int SQL_OV_ODBC3 = 3;
      private const short SQL_SUCCESS = 0;
      private const short SQL_NEED_DATA = 99;
      private const short DEFAULT_RESULT_SIZE = 1024;
      private const string SQL_DRIVER_STR = "DRIVER=SQL SERVER";
      private SqlLocator() { }
      
      /// <summary>
      /// 获取本地网站SQL Server列表
      /// </summary>
      /// <returns></returns>
      public static string[] GetServers()
      {
         string[] retval = null;
         string txt = string.Empty;
         IntPtr henv = IntPtr.Zero;
         IntPtr hconn = IntPtr.Zero;
         StringBuilder inString = new StringBuilder(SQL_DRIVER_STR);
         StringBuilder outString = new StringBuilder(DEFAULT_RESULT_SIZE);
         short inStringLength = (short)inString.Length;
         short lenNeeded = 0;
         
         try
         {
            if (SQL_SUCCESS == SQLAllocHandle(SQL_HANDLE_ENV, henv, out henv))
            {
               if (SQL_SUCCESS == SQLSetEnvAttr(henv, SQL_ATTR_ODBC_VERSION, (IntPtr)SQL_OV_ODBC3, 0))
               {
                  if (SQL_SUCCESS == SQLAllocHandle(SQL_HANDLE_DBC, henv, out hconn))
                  {
                     if (SQL_NEED_DATA == SQLBrowseConnect(hconn, inString, inStringLength, outString, DEFAULT_RESULT_SIZE, out lenNeeded))
                     {
                        if (DEFAULT_RESULT_SIZE < lenNeeded)
                        {
                           outString.Capacity = lenNeeded;
                           if (SQL_NEED_DATA != SQLBrowseConnect(hconn, inString, inStringLength, outString, lenNeeded, out lenNeeded))
                           {
                              throw new ApplicationException("Unabled to aquire SQL Servers from ODBC driver.");
                           }
                        }
                        txt = outString.ToString();
                        int start = txt.IndexOf("{") + 1;
                        int len = txt.IndexOf("}") - start;
                        if ((start > 0) && (len > 0))
                        {
                           txt = txt.Substring(start, len);
                        }
                        else { txt = string.Empty; }
                     }
                  }
               }
            }
         }
         catch (Exception ex)
         {
            MessageBox.Show(ex.Message, "Acquire SQL Servier List Error");
            txt = string.Empty;
         }
         finally
         {
            if (hconn != IntPtr.Zero)
            {
               SQLFreeHandle(SQL_HANDLE_DBC, hconn);
            }
            if (henv != IntPtr.Zero)
            {
               SQLFreeHandle(SQL_HANDLE_ENV, hconn);
            }
            } if (txt.Length > 0)
            {
               retval = txt.Split(",".ToCharArray());
            }
            return retval;
         }
      }
   }
   
   

string[] srvs = SqlLocator.GetServers();

foreach (string srv in srvs)
  _SrvList.Items.Add(srv);