为DataGrid添加自定义DataGridColumn类的例子 (转)

reference from http://lovecherry.cnblogs.com/lovecherry/archive/2005/05/01/148504.html

DataGrid的模板列可以方便的定制所需要的样式，比如上图：
在编辑状态的时候学院是下拉框，选择了当前的学院，但是如果学院很多，下拉框会很长，找起来也会很麻烦，所以可能需要再增加一个查找的功能。这样一个列完全可以通过模板列来实现，可是如果项目中有很多这样的需求，添加这么多复杂的模板列一来很麻烦，二来也有代码冗余，没有重用性，为此，我们可以尝试定制自己的DataGridColumn（类似已经存在的HyperLinkColumn）来为这个列进行小小的封装。

先建立一个类文件：

using  System;
using  System.Data;
using  System.Web.UI;
using  System.Web.UI.WebControls;

namespace  csdn
{
    public class MyColumn:DataGridColumn
    {
        public string DataTextField;
        public string DataValueField;
        public DataTable DataSource;
                        
        public override void InitializeCell(TableCell cell,int columnIndex,ListItemType itemType)
        {
            base.InitializeCell(cell,columnIndex,itemType);
            switch(itemType)
            {
                case ListItemType.Header:
                    cell.Text=this.HeaderText;
                    break;
                case ListItemType.Item:case ListItemType.AlternatingItem:
                    cell.DataBinding+=new EventHandler(this.cell_ItemDataBinding);
                    break;
                case ListItemType.EditItem:
                    cell.DataBinding +=new EventHandler(cell_EditItemDataBinding);
                    DropDownList ddl=new DropDownList();
                    cell.Controls.Add(ddl);
                    TextBox t=new TextBox();
                    t.Width=80;
                    cell.Controls.Add(t);
                    Button b=new Button();
                    b.Text="查找";
                    b.Click+=new EventHandler(this.btn_Click);
                    cell.Controls.Add(b);
                    break;
            }
        }

        private void cell_ItemDataBinding(object sender, EventArgs e)
        {
            TableCell cell=(TableCell)sender;
            DataGridItem dgi=(DataGridItem)cell.NamingContainer;
            cell.Text=(DataBinder.Eval(dgi.DataItem,this.DataTextField)).ToString();
        }

        private void cell_EditItemDataBinding(object sender,EventArgs e)
        {
            TableCell cell=(TableCell)sender;
            DropDownList ddl=(DropDownList)cell.Controls[0];
            DataGridItem dgi=(DataGridItem)cell.NamingContainer;
            for(int i=0;i<this.DataSource.Rows.Count;i++)
                ddl.Items.Add(new ListItem(this.DataSource.Rows[i][this.DataTextField].ToString(),this.DataSource.Rows[i][this.DataValueField].ToString()));
            ddl.Items.FindByValue((DataBinder.Eval(dgi.DataItem,this.DataValueField)).ToString()).Selected=true;
        }

        private void btn_Click(object sender,EventArgs e)
        {
            TableCell cell=(TableCell)(((Button)sender).Parent);
            DropDownList ddl=(DropDownList)cell.Controls[0];
            TextBox t=(TextBox)cell.Controls[1];
            DataGridItem dgi=(DataGridItem)cell.NamingContainer;
            ListItem li=ddl.Items.FindByText(t.Text);
            if(li!=null)
            {
                ddl.SelectedIndex=-1;
                li.Selected=true;
            }
        }
    }
}

然后为页面添加这个自定义列：

<% @ Page language="c#" Codebehind="WebForm67.aspx.cs" AutoEventWireup="false" Inherits="csdn.WebForm67"  %>
<% @ Register TagPrefix="MyDataGridColumn" Assembly="csdn" NameSpace="csdn" %>
<! DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"  >
< HTML >
     < HEAD >
         < title > Test </ title >
         < META  http-equiv ="Content-Type"  content ="text/html; charset=gb2312" >
         < meta  content ="Microsoft Visual Studio .NET 7.1"  name ="GENERATOR" >
         < meta  content ="C#"  name ="CODE_LANGUAGE" >
         < meta  content ="JavaScript"  name ="vs_defaultClientScript" >
         < meta  content ="http://schemas.microsoft.com/intellisense/ie5"  name ="vs_targetSchema" >
         < LINK  href ="css.css"  type ="text/css"  rel ="stylesheet" >
     </ HEAD >
     < body >
         < form  id ="Form1"  method ="post"  runat ="server" >
             < asp:datagrid  id ="DataGrid1"  runat ="server"  DataKeyField ="stuid"  CellSpacing ="1"  BorderWidth ="0px"
                OnEditCommand ="edit"  OnCancelCommand ="cancel"  OnUpdateCommand ="update"  CellPadding ="5"  CssClass ="border"
                AutoGenerateColumns ="False" >
                 < ItemStyle  CssClass ="item" ></ ItemStyle >
                 < HeaderStyle  CssClass ="header" ></ HeaderStyle >
                 < Columns >
                     < asp:BoundColumn  HeaderText ="姓名"  DataField ="stuname" ></ asp:BoundColumn >
                     < MyDataGridColumn:MyColumn  HeaderText ="学院"  DataTextField ="depname"  DataValueField ="depid" ></ MyDataGridColumn:MyColumn >
                     < asp:EditCommandColumn  ButtonType ="PushButton"  UpdateText ="更新"  CancelText ="取消"  EditText ="编辑" ></ asp:EditCommandColumn >
                 </ Columns >
             </ asp:datagrid >
         </ form >
     </ body >
</ HTML >

后台代码如下：

using  System;
using  System.Collections;
using  System.ComponentModel;
using  System.Data;
using  System.Data.SqlClient;
using  System.Drawing;
using  System.Web;
using  System.Web.SessionState;
using  System.Web.UI;
using  System.Web.UI.WebControls;
using  System.Web.UI.HtmlControls;

namespace  csdn
{
    /**//// <summary>
    /// WebForm67 的摘要说明。
    /// </summary>
    public class WebForm67 : System.Web.UI.Page
    {
        protected System.Web.UI.WebControls.DataGrid DataGrid1;
        
        private void Page_Load(object sender, System.EventArgs e)
        {
            // 在此处放置用户代码以初始化页面
            if(!IsPostBack)
            {
                SetBind();
            }            
        }

        protected void SetBind()
        {
            SqlConnection conn=new SqlConnection(System.Configuration.ConfigurationSettings.AppSettings["conn"]);
            SqlDataAdapter da=new SqlDataAdapter("select * from stu,dep where stu.studepid=dep.depid",conn);
            DataSet ds=new DataSet();
            da.Fill(ds);
            this.DataGrid1.DataSource=ds.Tables[0];
            this.DataGrid1.DataBind();            
        }

        protected void edit(object sender,DataGridCommandEventArgs e)
        {
            this.DataGrid1.EditItemIndex=e.Item.ItemIndex;
            SetBind();
            
        }

        protected void cancel(object sender,DataGridCommandEventArgs e)
        {
            this.DataGrid1.EditItemIndex=-1;
            SetBind();
        }

        protected void update(object sender,DataGridCommandEventArgs e)
        {
            if(e.Item.ItemType==ListItemType.EditItem)
            {
                SqlConnection conn=new SqlConnection(System.Configuration.ConfigurationSettings.AppSettings["conn"]);
                SqlCommand comm=new SqlCommand("update stu set stuname=@name,studepid=@depid where stuid=@id",conn);
                SqlParameter parm1=new SqlParameter("@name",SqlDbType.NVarChar,50);
                parm1.Value=((TextBox)e.Item.Cells[0].Controls[0]).Text;
                SqlParameter parm2=new SqlParameter("@depid",SqlDbType.Int);
                parm2.Value=((DropDownList)e.Item.Cells[1].Controls[0]).SelectedValue;
                SqlParameter parm3=new SqlParameter("@id",SqlDbType.Int);
                parm3.Value=this.DataGrid1.DataKeys[e.Item.ItemIndex];
                comm.Parameters.Add(parm1);
                comm.Parameters.Add(parm2);
                comm.Parameters.Add(parm3);
                conn.Open();
                comm.ExecuteNonQuery();
                conn.Close();
                this.DataGrid1.EditItemIndex=-1;
                SetBind();
            }
        }

        Web 窗体设计器生成的代码#region Web 窗体设计器生成的代码
        override protected void OnInit(EventArgs e)
        {
            //
            // CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。
            //
            InitializeComponent();
            base.OnInit(e);
        }
        
        /**//// <summary>
        /// 设计器支持所需的方法 - 不要使用代码编辑器修改
        /// 此方法的内容。
        /// </summary>
        private void InitializeComponent()
        {    
            this.DataGrid1.ItemDataBound += new System.Web.UI.WebControls.DataGridItemEventHandler(this.DataGrid1_ItemDataBound);
            this.Load += new System.EventHandler(this.Page_Load);

        }
        #endregion

        private void DataGrid1_ItemDataBound(object sender, System.Web.UI.WebControls.DataGridItemEventArgs e)
        {
            SqlConnection conn=new SqlConnection(System.Configuration.ConfigurationSettings.AppSettings["conn"]);
            SqlDataAdapter da=new SqlDataAdapter("select * from dep",conn);
            DataSet ds=new DataSet();
            da.Fill(ds);
            ((MyColumn)this.DataGrid1.Columns[1]).DataSource=ds.Tables[0];
        }
    }
}

这个例子可能稍微复杂了点(列中放了3个控件)，但是原理比较简单，其实简化一下，我们可以封装自己的DropDownListColumn、CheckBoxColumn等单控件列。