.net连接ACCESS数据库，网页上不停的刷新就报错

public class DB { public static OleDbConnection Conn; public static string ConnString;//连接字符串 public DB() { // // TODO: 在此处添加构造函数逻辑 // } public static OleDbConnection Getconn() { ConnString = "Provider=Microsoft.Jet.OLEDB.4

public class DB
{
public static OleDbConnection Conn;
public static string ConnString;//连接字符串

public DB()
{
//
// TODO: 在此处添加构造函数逻辑
//
}

public static OleDbConnection Getconn()
{
ConnString = "Provider=Microsoft.Jet.OLEDB.4.0;Data source=" + System.Web.HttpContext.Current.Server.MapPath(ConfigurationManager.AppSettings["ConnectionString"].ToString());
Conn = new OleDbConnection(ConnString);
//if (Conn.State.Equals(ConnectionState.Closed))
//{

// Conn.Open();

//}

if (Conn == null)
{
Conn = new OleDbConnection(ConnString);
Conn.Open();
}
else if (Conn.State == System.Data.ConnectionState.Closed)
{
Conn.Open();
}
else if (Conn.State == System.Data.ConnectionState.Broken)
{
Conn.Close();
Conn.Open();
}
return Conn;

}
//=================================================
//功能描述：关闭数据库
//时间：2010.11.10
//=================================================
private static void closeConnection()
{
OleDbConnection conn = DB.Getconn();
OleDbCommand cmd = new OleDbCommand();
if (conn.State == ConnectionState.Open)
{
conn.Close();
conn.Dispose();
cmd.Dispose();
}
}
//=================================================
//功能描述：执行SQL语句
//输入参数：sql，查询的SQL语句
//时间：2010.11.10
//=================================================
public static void execnonsql(string sql)
{
try
{
closeConnection();
OleDbConnection conn = DB.Getconn();
OleDbCommand com = new OleDbCommand(sql, conn);
com.ExecuteNonQuery();
}
catch (Exception e)
{
throw new Exception(e.Message);
}
finally
{
closeConnection();
}

}
//=================================================
//功能描述：获取DATASET
//输入参数：sql，查询的SQL语句
//返回值：DataSet
//时间：2010.11.10
//=================================================
public static DataSet getdataset(string sql)
{
try
{
closeConnection();
OleDbConnection conn = DB.Getconn();
OleDbDataAdapter adp = new OleDbDataAdapter(sql, conn);
DataSet ds = new DataSet();
adp.Fill(ds, "ds");
return ds;
}
catch (Exception e)
{
throw new Exception(e.Message);

}
finally
{
closeConnection();
}
}
//=================================================
//功能描述：获取DATASET1
//输入参数：sql，查询的SQL语句
//返回值：DataSet
//时间：2010.11.10
//=================================================
public static DataSet select(string sql, string tablename)
{
try
{
closeConnection();
OleDbConnection conn = DB.Getconn();
OleDbDataAdapter adp = new OleDbDataAdapter(sql, conn);
DataSet ds = new DataSet();
adp.Fill(ds, tablename);
return ds;
}
catch (Exception e)
{
throw new Exception(e.Message);

}
finally
{
closeConnection();
}
}
//=================================================
//功能描述：获取某个字段数据
//输入参数：sql，查询的SQL语句
//返回值：hang
//时间：2010.11.10
//=================================================
public static string FindString(string sql)
{
try
{
closeConnection();
OleDbConnection conn = DB.Getconn();
OleDbCommand com = new OleDbCommand(sql, conn);
string hang = Convert.ToString(com.ExecuteScalar());
return hang;
}
catch (Exception e)
{
throw new Exception(e.Message);

}
finally
{
closeConnection();
}

}
//=================================================
//功能描述：对DATAGRIG进行数据绑定，无排序
//输入参数：sql，查询的SQL语句；dg，需要绑定的DATAGRID控件
//返回值：无
//时间：2010.11.10
//=================================================
public static void binddatagrid(string sql, DataGrid dg)
{

try
{
DataSet ds = getdataset(sql);
dg.DataSource = ds.Tables[0].DefaultView;
dg.DataBind();
}
catch (Exception e)
{
throw new Exception(e.Message);

}
finally
{
closeConnection();
}
}
//=================================================
//功能描述：对DropDownList进行数据绑定，无排序
//输入参数：sql，查询的SQL语句；dg，需要绑定的DATAGRID控件
//返回值：无
//时间：2010.11.10
//=================================================
public static void bindDropDownList(string sql, DropDownList dl, string class_name, string id)
{

try
{
DataSet ds = getdataset(sql);
dl.DataSource = ds.Tables[0].DefaultView;
dl.DataTextField = class_name;
dl.DataValueField = id;
dl.DataBind();
}
catch (Exception e)
{
throw new Exception(e.Message);

}
finally
{
closeConnection();
}
}
//=================================================
//功能描述：对RadioButtonList进行数据绑定，无排序
//输入参数：sql，查询的SQL语句；dg，需要绑定的DATAGRID控件
//返回值：无
//时间：2010.11.10
//=================================================
public static void bindRadioButtonList(string sql, RadioButtonList rl, string class_name, string id)
{

try
{
DataSet ds = getdataset(sql);
rl.DataSource = ds.Tables[0].DefaultView;
rl.DataTextField = class_name;
rl.DataValueField = id;
rl.SelectedIndex = 0;
rl.DataBind();
}
catch (Exception e)
{
throw new Exception(e.Message);

}
finally
{
closeConnection();
}
}
//=================================================
//功能描述：对GridView进行数据绑定，无排序
//输入参数：sql，查询的SQL语句；dg，需要绑定的DATAGRID控件
//返回值：无
//时间：2010.11.10
//=================================================
public static void bindGridView(string sql, GridView dg)
{
try
{
closeConnection();
OleDbConnection conn = DB.Getconn();
DataSet ds = getdataset(sql);
dg.DataSource = ds.Tables[0].DefaultView;
dg.DataBind();
}
catch (Exception e)
{
throw new Exception(e.Message);

}
finally
{
closeConnection();
}
}
//=================================================
//功能描述：对datalist进行数据绑定，无排序
//输入参数：sql，查询的SQL语句；dl，需要绑定的datalist控件
//返回值：无
//时间：2010.11.10
//=================================================
public static void binddatalist(string sql, DataList dl)
{
try
{
closeConnection();
OleDbConnection conn = DB.Getconn();
DataSet ds = getdataset(sql);
dl.DataSource = ds.Tables[0].DefaultView;
dl.DataBind();
}
catch (Exception e)
{
throw new Exception(e.Message);

}
finally
{
closeConnection();
}
}
//=================================================
//功能描述：对repeater进行数据绑定，无排序
//输入参数：sql，查询的SQL语句；dl，需要绑定的repeater控件
//返回值：无
//时间：2010.11.10
//=================================================
public static void bindrepeater(string sql, Repeater rp)
{
try
{
closeConnection();
OleDbConnection conn = DB.Getconn();
DataSet ds = getdataset(sql);
rp.DataSource = ds.Tables[0].DefaultView;
rp.DataBind();
}
catch (Exception e)
{
throw new Exception(e.Message);

}
finally
{
closeConnection();
}
}
//=================================================
//功能描述：对listbox进行数据绑定
//输入参数：sql，查询的SQL语句；listb，需要绑定的listbox控件
//返回值：无
//时间：2010.11.10
//=================================================
public static void bindlistbox(string sql, ListBox listb, string class_name, string id)
{
try
{
closeConnection();
OleDbConnection conn = DB.Getconn();
DataSet ds = getdataset(sql);
listb.DataSource = ds.Tables[0].DefaultView;
listb.DataTextField = class_name;
listb.DataValueField = id;
listb.DataBind();
}
catch (Exception e)
{
throw new Exception(e.Message);

}
finally
{
closeConnection();
}
}
///

/// 返回 HTML 字符串的编码结果
///

/// 字符串
/// 编码结果
public static string HtmlEncode(string str)
{
return HttpUtility.HtmlEncode(str);
}

///

/// 返回 HTML 字符串的解码结果
///

/// 字符串
/// 解码结果
public static string HtmlDecode(string str)
{
return HttpUtility.HtmlDecode(str);
}
///

/// 检测是否有Sql危险字符
///

/// 要判断字符串
/// 判断结果
public static bool IsSafeSqlString(string str)
{

return !Regex.IsMatch(str, @"[-|;|,|\/|\(|\)|\[|\]|\}|\{|%|@|\*|!|\']");
}
///

/// 检测用户登录。
///

///
///
public static string UserCheck(string username, string userpass)
{
string strsql = "select count(*) from Member where mem_Name='" + username + "' and mem_Password='" + userpass + "'";
OleDbConnection conn = DB.Getconn();
OleDbCommand com = new OleDbCommand(strsql, conn);
string hang = Convert.ToString(com.ExecuteScalar());
return hang;
}

}