简介：
在本文中我们将具体介绍如何将ASP.Net 2.0下的GridView导出为Excel.
本文的焦点是Gridview导为Excel功能和它的数据绑定只出口示范功能.
本文代码可以用来导出为Excel的功能但不局限于这个部分，还可以在很多项目中使用。
Step 1: Setup your web page with the Gridview
这里我假定你满足：在一个页面中有个名为GridView1的GridView。在GridView中我们绑定了一个名为ContactPhone的SQL数据库。接下来的代码就是如何将GridView导出为Excel并且不依赖于具体的数据绑定还具有场景自改变能力。
ContactPhone Table Structure:
|
Column Name |
Type |
|
ContactID |
Int (Identity) |
|
FName |
Varchar(50) |
|
LName |
Varchar(50) |
|
ContactPhone |
Varchar(20) |
Step: The Actual Export
这段代码是直接输出为Excel的，你也可以改变content-disposition和ContentType以输出不同的类型。
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string attachment = ” attachment; filename=Contacts.xls ” ;
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Response.ClearContent();
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Response.AddHeader( ” content-disposition ” , attachment);
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Response.ContentType = ” application/ms-excel ” ;
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StringWriter sw = new StringWriter();
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HtmlTextWriter htw = new HtmlTextWriter(sw);
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GridView1.RenderControl(htw);
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Response.Write(sw.ToString());
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Response.End();
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string attachment = ” attachment; filename=Contacts.xls ” ;2
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Response.ClearContent();4
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Response.AddHeader( ” content-disposition ” , attachment);6
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Response.ContentType = ” application/ms-excel ” ;8
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StringWriter sw = new StringWriter();10
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HtmlTextWriter htw = new HtmlTextWriter(sw);12
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GridView1.RenderControl(htw);14
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Response.Write(sw.ToString());16
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Response.End(); 18
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如果你运行以上代码，将返回一个HttpException：
‘GridView1’是一个类型为’GridView’的控件，必须为其添加一个runat=server标记.
为避免这个错误，我们添加以下代码：
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public override void VerifyRenderingInServerForm(Control control)
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{
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}
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public override void VerifyRenderingInServerForm(Control control)2
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{
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}6
Step : Convert the contents
如果GridView中有其它控件，比如Checkboxes，Dropdownlists，我们需要将它转换为其相关的值，以下递归就用于导出Excel前的准备工作,将各类控件转换为其相关值.
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private void PrepareGridViewForExport(Control gv)
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3
{
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5 LinkButton lb = new LinkButton();
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7 Literal l = new Literal();
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9 string name = String.Empty;
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11 for (int i = 0; i < gv.Controls.Count; i++)
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{
14
15 if (gv.Controls[i].GetType() == typeof(LinkButton))
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17 {
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19 l.Text = (gv.Controls[i] as LinkButton).Text;
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21 gv.Controls.Remove(gv.Controls[i]);
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23 gv.Controls.AddAt(i, l);
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}
26
27 else if (gv.Controls[i].GetType() == typeof(DropDownList))
28
29 {
30
31 l.Text = (gv.Controls[i] as DropDownList).SelectedItem.Text;
32
33 gv.Controls.Remove(gv.Controls[i]);
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35 gv.Controls.AddAt(i, l);
36
37 }
38
39 else if (gv.Controls[i].GetType() == typeof(CheckBox))
40
41 {
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43 l.Text = (gv.Controls[i] as CheckBox).Checked? “True” : “False”;
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45 gv.Controls.Remove(gv.Controls[i]);
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47 gv.Controls.AddAt(i, l);
48
49 }
50
51 if (gv.Controls[i].HasControls())
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53 {
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55 PrepareGridViewForExport(gv.Controls[i]);
56
57 }
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59}
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private void PrepareGridViewForExport(Control gv)2
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{
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LinkButton lb = new LinkButton();6
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Literal l = new Literal();8
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string name = String.Empty;10
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for (int i = 0; i < gv.Controls.Count; i++)12
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{14
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if (gv.Controls[i].GetType() == typeof(LinkButton))16
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{18
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l.Text = (gv.Controls[i] as LinkButton).Text;20
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gv.Controls.Remove(gv.Controls[i]);22
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gv.Controls.AddAt(i, l);24
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}26
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else if (gv.Controls[i].GetType() == typeof(DropDownList))28
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{30
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l.Text = (gv.Controls[i] as DropDownList).SelectedItem.Text;32
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gv.Controls.Remove(gv.Controls[i]);34
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gv.Controls.AddAt(i, l);36
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}38
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else if (gv.Controls[i].GetType() == typeof(CheckBox))40
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{42
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l.Text = (gv.Controls[i] as CheckBox).Checked? “True” : “False”;44
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gv.Controls.Remove(gv.Controls[i]);46
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gv.Controls.AddAt(i, l);48
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}50
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if (gv.Controls[i].HasControls())52
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{54
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PrepareGridViewForExport(gv.Controls[i]);56
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}58
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}60
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Code Listing:
Image: Page Design
Image : Sample in action
Image: Export to Excel button is clicked
Image: GridView contents exported to Excel
ExcelExport.aspx
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<%@ Page Language=”C#” AutoEventWireup=”true” CodeFile=”ExportExcel.aspx.cs” Inherits=”DeleteConfirm” %>2
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<!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Transitional//EN” “http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd”>6
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8
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<html xmlns=”http://www.w3.org/1999/xhtml” >10
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<head runat=”server”>12
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<title>Contacts Listing</title>14
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</head>16
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<body>18
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<form id=”form1″ runat=”server”>20
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<div>22
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<strong><span style=”font-size: small; font-family: Arial; text-decoration: underline”>24
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Contacts Listing 26
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<asp:Button ID=”Button1″ runat=”server” OnClick=”Button1_Click” Text=”Export To Excel” /></span></strong><br />28
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<br />30
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<asp:GridView ID=”GridView1″ runat=”server” AutoGenerateColumns=”False” DataKeyNames=”ContactID”32
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DataSourceID=”SqlDataSource1″ EmptyDataText=”There are no data records to display.” style=”font-size: small; font-family: Arial” BackColor=”White” BorderColor=”#DEDFDE” BorderStyle=”None” BorderWidth=”1px” CellPadding=”4″ ForeColor=”Black” GridLines=”Vertical”>34
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<Columns>36
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<asp:BoundField DataField=”ContactID” HeaderText=”ContactID” ReadOnly=”True” SortExpression=”ContactID” Visible=”False” />38
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<asp:BoundField DataField=”FName” HeaderText=”First Name” SortExpression=”FName” />40
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<asp:BoundField DataField=”LName” HeaderText=”Last Name” SortExpression=”LName” />42
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<asp:BoundField DataField=”ContactPhone” HeaderText=”Phone” SortExpression=”ContactPhone” />44
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<asp:TemplateField HeaderText=”Favorites”>46
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<ItemTemplate>48
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50
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<asp:CheckBox ID=”CheckBox1″ runat=”server” />52
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</ItemTemplate></asp:TemplateField>54
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</Columns>56
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<FooterStyle BackColor=”#CCCC99″ />58
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<RowStyle BackColor=”#F7F7DE” />60
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<SelectedRowStyle BackColor=”#CE5D5A” Font-Bold=”True” ForeColor=”White” />62
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<PagerStyle BackColor=”#F7F7DE” ForeColor=”Black” HorizontalAlign=”Right” />64
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<HeaderStyle BackColor=”#6B696B” Font-Bold=”True” ForeColor=”White” />66
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<AlternatingRowStyle BackColor=”White” />68
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</asp:GridView>70
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72
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<asp:SqlDataSource ID=”SqlDataSource1″ runat=”server” ConnectionString=”<%$ ConnectionStrings:ContactsConnectionString1 %>”74
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DeleteCommand=”DELETE FROM [ContactPhone] WHERE [ContactID] = @ContactID” InsertCommand=”INSERT INTO [ContactPhone] ([FName], [LName], [ContactPhone]) VALUES (@FName, @LName, @ContactPhone)”76
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ProviderName=”<%$ ConnectionStrings:ContactsConnectionString1.ProviderName %>”78
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SelectCommand=”SELECT [ContactID], [FName], [LName], [ContactPhone] FROM [ContactPhone]”80
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UpdateCommand=”UPDATE [ContactPhone] SET [FName] = @FName, [LName] = @LName, [ContactPhone] = @ContactPhone WHERE [ContactID] = @ContactID”>82
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<InsertParameters>84
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<asp:Parameter Name=”FName” Type=”String” />86
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<asp:Parameter Name=”LName” Type=”String” />88
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<asp:Parameter Name=”ContactPhone” Type=”String” />90
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</InsertParameters>92
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<UpdateParameters>94
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<asp:Parameter Name=”FName” Type=”String” />96
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<asp:Parameter Name=”LName” Type=”String” />98
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<asp:Parameter Name=”ContactPhone” Type=”String” />100
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<asp:Parameter Name=”ContactID” Type=”Int32″ />102
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</UpdateParameters>104
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<DeleteParameters>106
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<asp:Parameter Name=”ContactID” Type=”Int32″ />108
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</DeleteParameters>110
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</asp:SqlDataSource>112
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<br />116
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</div>118
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</form>120
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</body>122
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</html>124
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ExcelExport.aspx.cs
1
using System;2
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using System.Data;4
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using System.Configuration;6
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using System.Collections;8
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using System.Web;10
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using System.Web.Security;12
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using System.Web.UI;14
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using System.Web.UI.WebControls;16
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using System.Web.UI.WebControls.WebParts;18
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using System.Web.UI.HtmlControls;20
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using System.Text;22
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using System.IO;24
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public partial class DeleteConfirm : System.Web.UI.Page28
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{30
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32
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protected void Page_Load(object sender, EventArgs e)34
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{36
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}38
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protected void Button1_Click(object sender, EventArgs e)42
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{44
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//Export the GridView to Excel46
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PrepareGridViewForExport(GridView1);48
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ExportGridView();50
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}52
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private void ExportGridView()56
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{58
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string attachment = “attachment; filename=Contacts.xls”;60
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Response.ClearContent();62
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Response.AddHeader(“content-disposition”, attachment);64
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Response.ContentType = “application/ms-excel”;66
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StringWriter sw = new StringWriter();68
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HtmlTextWriter htw = new HtmlTextWriter(sw);70
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GridView1.RenderControl(htw);72
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Response.Write(sw.ToString());74
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Response.End();76
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}78
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80
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public override void VerifyRenderingInServerForm(Control control)82
83
{84
85
}86
87
88
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private void PrepareGridViewForExport(Control gv)90
91
{92
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LinkButton lb = new LinkButton();94
95
Literal l = new Literal();96
97
string name = String.Empty;98
99
for (int i = 0; i < gv.Controls.Count; i++)100
101
{102
103
if (gv.Controls[i].GetType() == typeof(LinkButton))104
105
{106
107
l.Text = (gv.Controls[i] as LinkButton).Text;108
109
gv.Controls.Remove(gv.Controls[i]);110
111
gv.Controls.AddAt(i, l);112
113
}114
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else if (gv.Controls[i].GetType() == typeof(DropDownList))116
117
{118
119
l.Text = (gv.Controls[i] as DropDownList).SelectedItem.Text;120
121
gv.Controls.Remove(gv.Controls[i]);122
123
gv.Controls.AddAt(i, l);124
125
}126
127
else if (gv.Controls[i].GetType() == typeof(CheckBox))128
129
{130
131
l.Text = (gv.Controls[i] as CheckBox).Checked ? “True” : “False”;132
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gv.Controls.Remove(gv.Controls[i]);134
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gv.Controls.AddAt(i, l);136
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}138
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if (gv.Controls[i].HasControls())140
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{142
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PrepareGridViewForExport(gv.Controls[i]);144
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}146
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}148
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}150
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}152
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Implementation Options:
通常情况,在输出函数中开发人员都会面临一个错误,典型的就是”RegisterForEventValidation can only be called during Render();”
访问者通常会在评论中提出一些好的建议.我特别要强调的是开发者需要重写VerifyRenderingInServerForm方法,该方法描述如下:
- Step 1:实现导出功能的上述功能.
- Step 2:重写一个VerifyRenderingInServerForm的空方法.
- Step 3:修改ExportGridView函数,在绿色高亮代码部创建HtmlForm【原句为:The code highlighted in green creates and HtmlForm on the fly,在翻译HtmlForm on the fly时遇到了一些困难,故on the fly未翻译,请各位高手指教】,在导出girdview之前，添加gridview 到新的form并且render它（取代原来的render实现）
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private void ExportGridView()
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3
{
4
5 string attachment = “attachment; filename=Contacts.xls”;
6
7 Response.ClearContent();
8
9 Response.AddHeader(“content-disposition”, attachment);
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11 Response.ContentType = “application/ms-excel”;
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13 StringWriter sw = new StringWriter();
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15 HtmlTextWriter htw = new HtmlTextWriter(sw);
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17
18
19 // Create a form to contain the grid
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21 HtmlForm frm = new HtmlForm();
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23 GridView1.Parent.Controls.Add(frm);
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25 frm.Attributes[“runat”] = “server”;
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27 frm.Controls.Add(GridView1);
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29
30
31 frm.RenderControl(htw);
32
33 //GridView1.RenderControl(htw);
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35 Response.Write(sw.ToString());
36
37 Response.End();
38
39}
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private void ExportGridView()2
3
{
4
5
string attachment = “attachment; filename=Contacts.xls”;6
7
Response.ClearContent();8
9
Response.AddHeader(“content-disposition”, attachment);10
11
Response.ContentType = “application/ms-excel”;12
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StringWriter sw = new StringWriter();14
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HtmlTextWriter htw = new HtmlTextWriter(sw);16
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// Create a form to contain the grid20
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HtmlForm frm = new HtmlForm();22
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GridView1.Parent.Controls.Add(frm);24
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frm.Attributes[“runat”] = “server”;26
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frm.Controls.Add(GridView1);28
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frm.RenderControl(htw);32
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//GridView1.RenderControl(htw);34
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Response.Write(sw.ToString());36
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Response.End();38
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}40
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这样实施有个优势,就是可将其设置为复用代码类库,不用每次去复写基类的方法.
Note to readers:
Thank you for your comments and feedback! Happy coding!!!
ASP.Net 2.0: Export GridView to Excel – Part II
该文中将会在导出Excel 时GridView引入Hyperlink列,以至于需要使用更多的反射来重新设计原来的逻辑.
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