扩展GridView（八）——导出为Excel

GridView既强大又好用。为了让它更强大、更好用，我们来写一个继承自GridView的控件。
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扩展GridView（八）——导出为Excel

介绍
把GridView导出为一个Excel文件算是一个经常要用到的功能，也比较简单，我们来扩展一个GridView以实现这样的功能。


控件开发
1、新建一个继承自GridView的类。

/**//// <summary>
/// 继承自GridView
/// </summary>
[ToolboxData(@"<{0}:SmartGridView runat='server'></{0}:SmartGridView>")]
public class SmartGridView : GridView
{
}

2、重写OnRowCommand，以实现把GridView导出为Excel的功能

        /**//// <summary>
        /// OnRowCommand
        /// </summary>
        /// <param name="e"></param>
        protected override void OnRowCommand(GridViewCommandEventArgs e)
        {
            if (e.CommandName.ToLower() == "exporttoexcel")
            {
                System.Web.HttpContext.Current.Response.ClearContent();
                // e.CommandArgument用“;”隔开两部分，左边的部分为导出Excel的文件名称
                System.Web.HttpContext.Current.Response.AddHeader("content-disposition", "attachment; filename=" + e.CommandArgument.ToString().Split(';')[0] + ".xls");
                System.Web.HttpContext.Current.Response.ContentType = "application/excel";

                System.IO.StringWriter sw = new System.IO.StringWriter();
                HtmlTextWriter htw = new HtmlTextWriter(sw);

                // e.CommandArgument用“;”隔开两部分，右边的部分为需要隐藏的列的索引（列索引用“,”分开）
                if (e.CommandArgument.ToString().Split(';').Length > 1)
                {
                    foreach (string s in e.CommandArgument.ToString().Split(';')[1].Split(','))
                    {
                        int i;

                        if (!Int32.TryParse(s, out i))
                        {
                            throw new ArgumentException("需要隐藏的列的索引不是整数"); 
                        }

                        if (i > this.Columns.Count)
                        {
                            throw new ArgumentOutOfRangeException("需要隐藏的列的索引超出范围");
                        }

                        this.Columns[i].Visible = false;
                    }
                }

                // 隐藏“导出Excel”按钮
                ((Control)e.CommandSource).Visible = false;

                // 如果HeaderRow里的控件是button的话，则把它替换成文本
                foreach (TableCell tc in this.HeaderRow.Cells)
                {
                    // TableCell里的每个Control
                    foreach (Control c in tc.Controls)
                    {
                        // 如果控件继承自接口IButtonControl
                        if (c.GetType().GetInterface("IButtonControl") != null && c.GetType().GetInterface("IButtonControl").Equals(typeof(IButtonControl)))
                        {
                            // 如果该控件不是“导出Excel”按钮则把button转换成文本
                            if (!c.Equals(e.CommandSource))
                            {
                                tc.Controls.Clear();
                                tc.Text = ((IButtonControl)c).Text;
                            }
                        }
                    }
                }

                // 将服务器控件的内容输出到所提供的 System.Web.UI.HtmlTextWriter 对象中
                this.RenderControl(htw);

                System.Web.HttpContext.Current.Response.Write(sw.ToString());
                System.Web.HttpContext.Current.Response.End();
            }

            base.OnRowCommand(e);
        }

控件使用
添加这个控件到工具箱里，然后拖拽到webform上，在GridView内加一个按钮，把CommandName属性设置为“ExportToExcel”，CommandArgument属性的值用“;”做分隔符分为两部分，左边的部分为导出Excel的文件名称，右边的部分为需要隐藏的列的索引（列索引用“,”分开）
ObjData.cs

using System;
using System.Data;
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.ComponentModel;

/**//// <summary>
/// OjbData 的摘要说明
/// </summary>
public class OjbData
{
    public OjbData()
    {
        //
        // TODO: 在此处添加构造函数逻辑
        //
    }

    [DataObjectMethod(DataObjectMethodType.Select, true)]
    public DataTable Select()
    {
        DataTable dt = new DataTable();
        dt.Columns.Add("no", typeof(string));
        dt.Columns.Add("name", typeof(string));

        for (int i = 0; i < 30; i++)
        {
            DataRow dr = dt.NewRow();
            dr[0] = "no" + i.ToString().PadLeft(2, '0');
            dr[1] = "name" + i.ToString().PadLeft(2, '0');

            dt.Rows.Add(dr);
        }

        return dt;
    }
}

Default.aspx

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>

<!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>SmartGridView测试</title>
</head>
<body>
    <form id="form1" runat="server">
        <div>
            <yyc:SmartGridView ID="SmartGridView1" runat="server" AutoGenerateColumns="False"
                DataSourceID="ObjectDataSource1">
                <Columns>
                    <asp:TemplateField ItemStyle-Width="50px">
                        <headertemplate>
                            <asp:Button id="btnExportToExcel" runat="server" Text="Excel" CommandName="ExportToExcel" CommandArgument="ExcelFileName;5,6" />
                        </headertemplate>
                        <itemtemplate>
                            <%# Container.DataItemIndex + 1 %>
                        </itemtemplate>
                    </asp:TemplateField>
                    <asp:BoundField DataField="no" HeaderText="序号" SortExpression="no" ItemStyle-Width="100px" />
                    <asp:BoundField DataField="name" HeaderText="名称" SortExpression="name" ItemStyle-Width="100px" />
                    <asp:BoundField DataField="no" HeaderText="序号" SortExpression="no" ItemStyle-Width="100px" />
                    <asp:BoundField DataField="name" HeaderText="名称" SortExpression="name" ItemStyle-Width="100px" />
                    <asp:BoundField DataField="no" HeaderText="序号" SortExpression="no" ItemStyle-Width="100px" />
                    <asp:BoundField DataField="name" HeaderText="名称" SortExpression="name" ItemStyle-Width="100px" />
                </Columns>
            </yyc:SmartGridView>
            <asp:ObjectDataSource ID="ObjectDataSource1" runat="server" SelectMethod="Select"
                TypeName="OjbData"></asp:ObjectDataSource>
        </div>
    </form>
</body>
</html>

注意：为了防止出错要在.cs代码中加上下面这句

public override void VerifyRenderingInServerForm(Control control)
    {

    }

另外，如果你的GridView中含有命令按钮的话要在.aspx页面的头部中加上下面这个属性

EnableEventValidation="false"

OK
[源码下载]