绑定到分层数据
更新：2007 年 11 月
数据源控件可以使用表格数据（基于表的数据或关系数据）或分层数据，或者同时使用这两者。SqlDataSource 和 ObjectDataSource 控件是使用表格数据的数据源控件的示例。ASP.NET 中还包括以下两个可以轻松绑定到分层数据的数据源控件：一个是 XmlDataSource 控件，它使用文件或字符串中的 XML；另一个是 SiteMapDataSource 控件，它使用站点导航数据（默认情况下作为 XML 数据进行保留）。分层数据源控件用于只读环境中以显示数据。
本主题提供了如何将数据绑定控件绑定到分层数据源的更多信息。有关 XmlDataSource 和 SiteMapDataSource 控件的附加信息，请参见 XmlDataSource Web 服务器控件概述和 SiteMapDataSource Web 服务器控件概述。
将分层控件绑定到 XML 数据
从本质上讲，XML 是一种分层结构，可以使用 TreeView 或 Menu 控件等分层数据绑定控件显示在 ASP.NET 网页中。通过将分层控件的 DataSourceID 属性设置为 XmlDataSource 或 SiteMapDataSource 控件的 ID，可以绑定到分层数据源控件。
下面的代码示例演示绑定到 XmlDataSource 控件的 TreeView 控件。XML 数据是使用 XPath 查询进行筛选的。
<%@ Page Language="VB" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
Sub SelectRegion(sender As Object, e As EventArgs)
If RegionDropDownList.SelectedValue = "(Show All)" Then
PeopleDataSource.XPath = "/People/Person"
Else
Dim selectedValue As String = ""
Select Case RegionDropDownList.SelectedValue
Case "CA"
selectedValue = "CA"
Case "HI"
selectedValue = "HI"
Case "WA"
selectedValue = "WA"
Case Else
' Invalid value.
End Select
PeopleDataSource.XPath = "/People/Person[Address/Region='" & selectedValue & "']"
End If
PeopleTreeView.DataBind()
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>ASP.NET Example</title>
</head>
<body>
<form id="form1" runat="server">
<table border="0" cellpadding="3">
<tr>
<td valign="top">
<b>Select Region:</b>
<asp:DropDownList runat="server" id="RegionDropDownList" AutoPostBack="True"
OnSelectedIndexChanged="SelectRegion">
<asp:ListItem Selected="True">(Show All)</asp:ListItem>
<asp:ListItem>CA</asp:ListItem>
<asp:ListItem>HI</asp:ListItem>
<asp:ListItem>WA</asp:ListItem>
</asp:DropDownList>
</td>
<td valign="top">
<asp:XmlDataSource
id="PeopleDataSource"
runat="server"
XPath="/People/Person"
DataFile="~/App_Data/people.xml" />
<asp:TreeView
id="PeopleTreeView"
runat="server"
DataSourceID="PeopleDataSource">
<DataBindings>
<asp:TreeNodeBinding DataMember="LastName" TextField="#InnerText" />
<asp:TreeNodeBinding DataMember="FirstName" TextField="#InnerText" />
<asp:TreeNodeBinding DataMember="Street" TextField="#InnerText" />
<asp:TreeNodeBinding DataMember="City" TextField="#InnerText" />
<asp:TreeNodeBinding DataMember="Region" TextField="#InnerText" />
<asp:TreeNodeBinding DataMember="ZipCode" TextField="#InnerText" />
<asp:TreeNodeBinding DataMember="Title" TextField="#InnerText" />
<asp:TreeNodeBinding DataMember="Description" TextField="#InnerText" />
</DataBindings>
</asp:TreeView>
</td>
</tr>
</table>
</form>
</body>
</html>
<%@ Page Language="C#" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
void SelectRegion(object sender, EventArgs e)
{
if (RegionDropDownList.SelectedValue == "(Show All)")
PeopleDataSource.XPath = "/People/Person";
else
{
string selectedValue = "";
switch (RegionDropDownList.SelectedValue)
{
case "CA":
selectedValue = "CA";
break;
case "HI":
selectedValue = "HI";
break;
case "WA":
selectedValue = "WA";
break;
default:
// Invalid value.
break;
}
PeopleDataSource.XPath = "/People/Person[Address/Region='" + selectedValue + "']";
}
PeopleTreeView.DataBind();
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>ASP.NET Example</title>
</head>
<body>
<form id="form1" runat="server">
<table border="0" cellpadding="3">
<tr>
<td valign="top">
<b>Select Region:</b>
<asp:DropDownList runat="server" id="RegionDropDownList" AutoPostBack="True"
OnSelectedIndexChanged="SelectRegion">
<asp:ListItem Selected="True">(Show All)</asp:ListItem>
<asp:ListItem>CA</asp:ListItem>
<asp:ListItem>HI</asp:ListItem>
<asp:ListItem>WA</asp:ListItem>
</asp:DropDownList>
</td>
<td valign="top">
<asp:XmlDataSource
id="PeopleDataSource"
runat="server"
XPath="/People/Person"
DataFile="~/App_Data/people.xml" />
<asp:TreeView
id="PeopleTreeView"
runat="server"
DataSourceID="PeopleDataSource">
<DataBindings>
<asp:TreeNodeBinding DataMember="LastName" TextField="#InnerText" />
<asp:TreeNodeBinding DataMember="FirstName" TextField="#InnerText" />
<asp:TreeNodeBinding DataMember="Street" TextField="#InnerText" />
<asp:TreeNodeBinding DataMember="City" TextField="#InnerText" />
<asp:TreeNodeBinding DataMember="Region" TextField="#InnerText" />
<asp:TreeNodeBinding DataMember="ZipCode" TextField="#InnerText" />
<asp:TreeNodeBinding DataMember="Title" TextField="#InnerText" />
<asp:TreeNodeBinding DataMember="Description" TextField="#InnerText" />
</DataBindings>
</asp:TreeView>
</td>
</tr>
</table>
</form>
</body>
</html>
将表格控件绑定到 XML 数据
虽然 XmlDataSource 控件主要用于向 TreeView 和 Menu 等分层数据绑定控件公开 XML 数据，但是，也可以将 GridView 或 DataList 等表格数据绑定控件绑定到 XmlDataSource 控件。
将表格数据绑定控件绑定到 XmlDataSource 控件时，该数据绑定控件只呈现 XML 层次结构的第一层。但是，在数据绑定控件模板中，还可以使用 XPath 和 XPathSelect 数据绑定方法绑定到 XML 层次结构中的特定元素。XPath 数据绑定方法将从某个节点或层次结构中任何位置的某个属性中返回一个值。XPathSelect 方法返回与 XPath 表达式匹配的节点列表。表格数据控件可以使用这些节点，如同它们是数据记录的集合一样。
有关更多信息和示例，请参见将表格控件绑定到 XmlDataSource 控件。
其他形式的分层数据
除了将控件绑定到本主题中演示的 XmlDataSource 控件之外，还可以将分层控件绑定到站点地图文件。有关更多信息，请参见 ASP.NET 站点地图。下面的代码示例演示如何将 Menu 控件绑定到 SiteMapDataSource 控件。
<%@ Page Language="VB" %>
<!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" >
<!-- For the hover styles of the Menu control to -->
<!-- work correctly, you must include this head -->
<!-- element. -->
<head runat="server">
<title>Menu DataBinding Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>Menu DataBinding Example</h3>
<!-- Bind the Menu control to a SiteMapDataSource control. -->
<asp:menu id="NavigationMenu"
disappearafter="2000"
staticdisplaylevels="2"
staticsubmenuindent="10"
orientation="Vertical"
font-names="Arial"
target="_blank"
datasourceid="MenuSource"
runat="server">
<staticmenuitemstyle backcolor="LightSteelBlue"
forecolor="Black"/>
<statichoverstyle backcolor="LightSkyBlue"/>
<dynamicmenuitemstyle backcolor="Black"
forecolor="Silver"/>
<dynamichoverstyle backcolor="LightSkyBlue"
forecolor="Black"/>
</asp:menu>
<asp:SiteMapDataSource id="MenuSource"
runat="server"/>
</form>
</body>
</html>
<%@ Page Language="C#" %>
<!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" >
<!-- For the hover styles of the Menu control to -->
<!-- work correctly, you must include this head -->
<!-- element. -->
<head runat="server">
<title>Menu DataBinding Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>Menu DataBinding Example</h3>
<!-- Bind the Menu control to a SiteMapDataSource control. -->
<asp:menu id="NavigationMenu"
disappearafter="2000"
staticdisplaylevels="2"
staticsubmenuindent="10"
orientation="Vertical"
font-names="Arial"
target="_blank"
datasourceid="MenuSource"
runat="server">
<staticmenuitemstyle backcolor="LightSteelBlue"
forecolor="Black"/>
<statichoverstyle backcolor="LightSkyBlue"/>
<dynamicmenuitemstyle backcolor="Black"
forecolor="Silver"/>
<dynamichoverstyle backcolor="LightSkyBlue"
forecolor="Black"/>
</asp:menu>
<asp:SiteMapDataSource id="MenuSource"
runat="server"/>
</form>
</body>
</html>
若要创建该示例的数据，可以将下面的示例站点地图数据复制到名为 Web.sitemap 的 Web 应用程序中的某个文件中。
<siteMap>
<siteMapNode url="~\Home.aspx"
title="Home"
description="Home">
<siteMapNode url="~\Music.aspx"
title="Music"
description="Music">
<siteMapNode url="~\Classical.aspx"
title="Classical"
description="Classical"/>
<siteMapNode url="~\Rock.aspx"
title="Rock"
description="Rock"/>
<siteMapNode url="~\Jazz.aspx"
title="Jazz"
description="Jazz"/>
</siteMapNode>
<siteMapNode url="~\Movies.aspx"
title="Movies"
description="Movies">
<siteMapNode url="~\Action.aspx"
title="Action"
description="Action"/>
<siteMapNode url="~\Drama.aspx"
title="Drama"
description="Drama"/>
<siteMapNode url="~\Musical.aspx"
title="Musical"
description="Musical"/>
</siteMapNode>
</siteMapNode>
</siteMap>