c# 连接池的设置与使用

 class DbConn
    {
        //using System.Data;
        //using System.Data.SqlClient;
        private const int MaxPool = 10;         //最大连接数
        private const int MinPool = 5;          //最小连接数
        private const bool Asyn_Process = true; //设置异步访问数据库
        private const bool Mars = true;         //在单个连接上得到和管理多个、仅向前引用和只读的结果集(ADO.NET2.0) 
        private const int Conn_Timeout = 15;    //设置连接等待时间
        private const int Conn_Lifetime = 15;   //设置连接的生命周期
        private string ConnString = "";         //连接字符串      
        private SqlConnection SqlDrConn = null;  //连接对象

        public DbConn()//构造函数
        {
            ConnString = GetConnString();
            SqlDrConn = new SqlConnection(ConnString);
        }

        private string GetConnString()
        {
            return "server=localhost;"
                + "integrated security=sspi;"
                + "database=pubs;"
                + "Max Pool Size=" + MaxPool + ";"
                + "Min Pool Size=" + MinPool + ";"
                + "Connect Timeout=" + Conn_Timeout + ";"
                + "Connection Lifetime=" + Conn_Lifetime + ";"
                +"Asynchronous Processing=" + Asyn_Process + ";";
                //+ "MultipleActiveResultSets=" + Mars + ";";
        }
       
        public DataTable GetDataReader(string StrSql)//数据查询
        {                    
            //当连接处于打开状态时关闭,然后再打开,避免有时候数据不能及时更新
            if (SqlDrConn.State == ConnectionState.Open)
            {
                SqlDrConn.Close();                
            }
            try
            {
                SqlDrConn.Open();
                SqlCommand SqlCmd = new SqlCommand(StrSql, SqlDrConn);
                SqlDataReader SqlDr = SqlCmd.ExecuteReader();
                if (SqlDr.HasRows)
                {
                    DataTable dt = new DataTable();
                    //读取SqlDataReader里的内容
                    dt.Load(SqlDr);
                    //关闭对象和连接
                    SqlDr.Close();
                    SqlDrConn.Close();                    
                    return dt;
                }
                return null;
            }
            catch (Exception ex)
            {
                System.Windows.Forms.MessageBox.Show(ex.Message);          
                return null;
            }
            finally
            {        
                SqlDrConn.Close();
            }
        }
    }