GridView&ObjectDataSource新特性小记 懒人篇(一) 分页上路

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GridView&ObjectDataSource新特性小记 懒人篇(一) 分页上路

Posted on 2006-04-13 19:34 笑看千秋_R

懒"归正传:
最近开场废话是多了点(可能是参加会议太多闹的.. ^_^!!).马上请出GridView & ObjectDataSource.
下面我将逐步展现一个分页的案例.

案例环境: WindowsXP SP2, VS2005 Team Suite,SqlServer2005(没有比这更糟的了....)
要求: 了解数据绑定控件的结构,数据源的运行机制,以及简单的绑定控件设计实现(那些内容足够再写一篇教程了,这里不再多叙.)
参 考: MSDN中提到,ObjectDataSource是唯一支持界面分页的数据源(除非自己来继承造一个,汗!),但示例仍 然是用SqlDataSource做数据源介绍的GirdView绑定.难道MS这么小气???(ps:打死俺也不说).

那好,就从那句介绍开始,咱们自己动手整出一个来.
按照常规,先准备一张表和一些存储过程,如下:




Table:MyUsers


UserID (int,primary key,identity) --自动增加字段,用户ID标识列


UserName (nvarchar(50),not null) --用户名


Description (nvarchar(50),not null)--备注




Procedure:




CREATE PROCEDURE [dbo].[AddUser] --增加一个用户


@UserName nvarchar(50),


@Description nvarchar(50)


AS


BEGIN


SET NOCOUNT ON;




begin transaction t





insert into MyUsers(UserName,Description)


values(@UserName,@Description)





if @@error <> 0


begin


rollback transaction t


end


else


begin


commit transaction


end


END




CREATE PROCEDURE [dbo].[DeleteUserByUserID] --删除一个用户


@UserID int


AS


BEGIN


SET NOCOUNT ON;




Begin Transaction t




delete from MyUsers where UserID =@UserID




if @@error <> 0


begin


rollback transaction t


end


else


begin


commit transaction


end


END




CREATE PROCEDURE [dbo].[UpdateUser] --修改用户姓名或备注


@UserID int,


@UserName nvarchar(50),


@Description nvarchar(50)


AS


BEGIN


SET NOCOUNT ON;




begin transaction t





update MyUsers


set UserName = @UserName,


Description = @Description


where UserID = @UserID




if @@error <> 0


begin


rollback transaction t


end


else


begin


commit transaction t


end


END




CREATE PROCEDURE [dbo].[GetUsers] --得到用户列表,注意这里的参数


@RowIndex int,


@RecordCount int


AS


BEGIN


SET NOCOUNT ON;




With VUsers as (


select *,row_number() over (order by UserID desc) as RowNum


from MyUsers


)




select * from VUsers


where RowNum > @RowIndex and RowNum <= (@RowIndex+@RecordCount)


END




CREATE PROCEDURE [dbo].[GetUsersCount]


AS


BEGIN


SET NOCOUNT ON;


select count(UserID) from MyUsers


END

这里详细说明一下倒数两个存储过程,GetUsers的参数RowIndex,不是页码(传说中的PageIndex),而是行索引,且从 0开始.这点特别要注意,因为要让ObjectDataSource自动取得当前需要的数据(界面级分页意味着当前需要显示多少数据只向数据库取多少,并 不会像其他数据源全总取出消耗性能.),依据也就是行索引和增量.GetUsersCount这个存储过程是为ObjectDataSource分页提供 总数的,它与分页的存储过程要保持一致.特别指的是有分页条件的情况,本人经常忘记(^_^||).否则GridView显示会不正常.

在WebSite新建一个DAL,假定类名为DataManager,给出代码片段如下:




using System;


using System.Data;


using System.Data.SqlClient;


using System.Configuration;


using System.Web;


using System.Web.Security;


using System.Web.UI;


using System.Web.UI.WebControls;


using System.Web.UI.WebControls.WebParts;


using System.Web.UI.HtmlControls;


using System.Collections;


using System.Collections.Generic;






/**//// <summary>


/// DataAccessLayer


/// </summary>


public class DataManager






{


private SqlConnection con = null; //连接对象


private SqlCommand cmd = null; //command执行对象


private SqlDataAdapter da = null; //适配器对象






/**//// <summary>


/// DAL对象构造


/// </summary>


public DataManager()






{


//


// TODO: Add constructor logic here


//


}






/**//// <summary>


/// 打开数据库连接


/// </summary>


private void OpenConnection()






{


try






{


string conString = ConfigurationManager.ConnectionStrings["localDB"].ConnectionString;


con = new SqlConnection(conString);


if (ConnectionState.Closed == con.State)






{


con.Open();


}


}


catch (SqlException ex)






{


throw new Exception("数据库无法访问", ex);


}


}






/**//// <summary>


/// 关闭数据库连接


/// </summary>


private void CloseConnection()






{


if (ConnectionState.Open == con.State)






{


try






{


con.Close();


}


catch (SqlException ex)






{


throw new Exception("数据库无法关闭", ex);


}


}


}






/**//// <summary>


/// 取得用户列表


/// </summary>


/// <param name="rowIndex">行索引</param>


/// <param name="recordCount">页显示量(增量)</param>


/// <returns>用户列表数据集</returns>


public DataSet GetUsers(int rowIndex, int recordCount)






{


OpenConnection();


try






{


cmd = new SqlCommand();


cmd.Connection = con;


cmd.CommandType = CommandType.StoredProcedure;


cmd.CommandText = "GetUsers";





SqlParameter spRowIndex = new SqlParameter("@RowIndex",SqlDbType.Int,4);


spRowIndex.Direction = ParameterDirection.Input;


SqlParameter spRecordCount = new SqlParameter("@RecordCount",SqlDbType.Int,4);


spRecordCount.Direction = ParameterDirection.Input;




cmd.Parameters.Add(spRowIndex);


cmd.Parameters.Add(spRecordCount);




spRowIndex.Value = rowIndex;


spRecordCount.Value = recordCount;




da = new SqlDataAdapter(cmd);


DataSet ds = new DataSet();





da.Fill(ds, "MyUsers");




return ds;


}


catch (SqlException ex)






{


throw new Exception("无法取得有效数据", ex);


}


finally






{


CloseConnection();


}


}






/**//// <summary>


/// 取得用户总数


/// </summary>


/// <returns>用户总数</returns>


public int GetUsersCount()






{


OpenConnection();


try






{


cmd = new SqlCommand();


cmd.Connection = con;


cmd.CommandType = CommandType.StoredProcedure;


cmd.CommandText = "GetUsersCount";


int count = Convert.ToInt32(cmd.ExecuteScalar().ToString());


return count;


}


catch (SqlException ex)






{


throw new Exception("无法取得有效数据", ex);


}


finally






{


CloseConnection();


}


}


对DAL也有几项说明,DataManager.GetUsers(int rowIndex, int recordCount)方法的参数只能有两个,
参数名可以随意,但意义却要与调用的存储过程GetUsers要一致,rowIndex必须是行索引,recordCount必须是页显示量.
OK！接下来在页面上放上一个GridView和一个ObjectDataSource,设置代码片段如下:




<asp:GridView ID="gvMyUsers" runat="server" AllowPaging="True" CellPadding="4" DataSourceID="objMyUsers" ForeColor="#333333" GridLines="None" AutoGenerateDeleteButton="True" AutoGenerateEditButton="True" AutoGenerateColumns="False" DataKeyNames="UserID" PageSize="10">


<FooterStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White" />


<RowStyle BackColor="#EFF3FB" />


<EditRowStyle BackColor="#2461BF" />


<SelectedRowStyle BackColor="#D1DDF1" Font-Bold="True" ForeColor="#333333" />


<PagerStyle BackColor="#2461BF" ForeColor="White" HorizontalAlign="Center" />


<HeaderStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White" />


<AlternatingRowStyle BackColor="White" />


</asp:GridView>


<asp:ObjectDataSource ID="objMyUsers" runat="server" EnablePaging="True" MaximumRowsParameterName="recordCount"


SelectCountMethod="GetUsersCount" SelectMethod="GetUsers" StartRowIndexParameterName="rowIndex" TypeName="DataManager">


</asp:ObjectDataSource>
指定每页显示最大数据量(页显示量)的参数:
MaximumRowsParameterName="recordCount"
指定取得数据总数方法:
SelectCountMethod="GetUsersCount"
指定分页方法:
SelectMethod="GetUsers"
指定起始行参数:
StartRowIndexParameterName="rowIndex"
指定前面方法所属类名(全限定名):
TypeName="DataManager
这几个设置是必须的,一定要对应.

现在轻轻的点击一下运行吧(什么什么?还没写事件?...我说老铁,都啥年月了,懒人还有用那玩儿吗?).到这里,一个最快速的分页其实已经做完了.

前面的步骤都是必须的,但仍然可以有一些变化.比如,若你已经按以往的办法写好了一个类似于


Create Procedure GetUsers


@PageIndex int,


@PageSize int


as


begin










end
这样的存储过程了,没关系,你在DAL的DataManager.GetUsers(int rowIndex, int recordCount)这里,
把rowIndex,recordCount在调用存储过程前转换成PageIndex,PageSize就好了,也不过是
PageIndex = rowIndex/recordCount +1; PageSize =recordCount;这样的语句就能搞定啦.再或者改存储过程里面也行(虽然有点不值得),不多说了.自己耍一把就知道了.
你一定心里还有疑问,没错,DataManager.GetUsers(int rowIndex, int recordCount)这个方法,更多时候需要多一些参数,也就是说,我们分页取数据的过程,还需要一些筛选条件,但这个方法是要给 ObjectDataSource的selectMethod方法,不能增加别的参数,形成矛盾怎么办??欲知解决之道,且等下回分解.....(快跑 啊.....鸡蛋来啦!!)