类库代码superConn.cs代码如下：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Data.OleDb;
namespace 练习
{
public class superConn
{
private OleDbConnection cnn;
private OleDbCommand cmd;
private OleDbDataReader datar;
public superConn(string mdbFileName){
string _path = "~\\App_Data\\" + mdbFileName;
string str_conn = "Provider=Microsoft.Jet.OLEDB.4.0; Data Source="
+ System.Web.HttpContext.Current.Server.MapPath(_path);//调用MapPath的完整命名空间
cnn = new OleDbConnection(str_conn);
}
//打开连接
public void open() {
cnn.Open();
}
//关闭连接
public void close() {
cnn.Close();
}
public OleDbDataReader getDateReader(string _sql) {
cmd = new OleDbCommand(_sql, cnn);
datar = cmd.ExecuteReader();
return datar;
}
}
}
.aspx代码如下：
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="测试自定义数据库连接类.aspx.cs" Inherits="练习.测试自定义数据库连接类" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:Button ID="Button1" runat="server" Text="Test" οnclick="Button1_Click" />
</div>
</form>
</body>
</html>
.aspx.cs代码如下：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.OleDb;
namespace 练习
{
public partial class 测试自定义数据库连接类 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void Button1_Click(object sender, EventArgs e)
{
superConn mycnn= new superConn("data.mdb");
mycnn.open();
string _sql="SELECT* FROM T_IMGS";
OleDbDataReader dr=mycnn.getDateReader(_sql);
while (dr.Read()) {
Response.Write(dr["img_url"].ToString()+"<br>");
}
mycnn.close();
}
}
}
测试运行时出现如下错误：
<span style="color:#ff0000;">“/”应用程序中的服务器错误。
在 ConnectionString 中未指定 OLE DB 提供程序。示例为:“Provider=SQLOLEDB;”。
说明: 执行当前 Web 请求期间，出现未经处理的异常。请检查堆栈跟踪信息，以了解有关该错误以及代码中导致错误的出处的详细信息。
异常详细信息: System.ArgumentException: 在 ConnectionString 中未指定 OLE DB 提供程序。示例为:“Provider=SQLOLEDB;”。
源错误:
行 16: string str_conn = "Provide=Microsoft.Jet.OLEDB.4.0; Data Source="
行 17: + System.Web.HttpContext.Current.Server.MapPath(_path);//调用MapPath的完整命名空间
行 18: cnn = new OleDbConnection(str_conn);
行 19: }
行 20: //打开连接
源文件: C:\Users\Administrator\documents\visual studio 2010\Projects\练习\练习\superConn.cs 行: 18
堆栈跟踪:
[ArgumentException: 在 ConnectionString 中未指定 OLE DB 提供程序。示例为:“Provider=SQLOLEDB;”。]
System.Data.OleDb.OleDbConnectionString.ValidateProvider(String progid) +1044395
System.Data.OleDb.OleDbConnectionString.ValidateConnectionString(String connectionString) +252
System.Data.OleDb.OleDbConnectionString..ctor(String connectionString, Boolean validate) +563
System.Data.OleDb.OleDbConnectionFactory.CreateConnectionOptions(String connectionString, DbConnectionOptions previous) +36
System.Data.ProviderBase.DbConnectionFactory.GetConnectionPoolGroup(String connectionString, DbConnectionPoolGroupOptions poolOptions, DbConnectionOptions& userConnectionOptions) +150
System.Data.OleDb.OleDbConnection.ConnectionString_Set(String value) +59
System.Data.OleDb.OleDbConnection.set_ConnectionString(String value) +4
System.Data.OleDb.OleDbConnection..ctor(String connectionString) +26
练习.superConn..ctor(String mdbFileName) in C:\Users\Administrator\documents\visual studio 2010\Projects\练习\练习\superConn.cs:18
练习.测试自定义数据库连接类.Button1_Click(Object sender, EventArgs e) in C:\Users\Administrator\documents\visual studio 2010\Projects\练习\练习\测试自定义数据库连接类.aspx.cs:20
System.Web.UI.WebControls.Button.OnClick(EventArgs e) +118
System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +112
System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10
System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13
System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +36
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +5563
</span>
根据错误提示进行代码检查，发现如下拼写错误：
修改后调试，得到如下正确结果：
