ASP.NET Web Forms - Hashtable 对象
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Hashtable 对象包含用键/值对表示的项目。
尝试一下 - 实例
Hashtable RadiobuttonList 1
<script runat="server">
sub Page_Load
if Not Page.IsPostBack then
dim mycountries=New Hashtable
mycountries.Add("N","Norway")
mycountries.Add("S","Sweden")
mycountries.Add("F","France")
mycountries.Add("I","Italy")
rb.DataSource=mycountries
rb.DataValueField="Key"
rb.DataTextField="Value"
rb.DataBind()
end if
end sub
sub displayMessage(s as Object,e As EventArgs)
lbl1.text="Your favorite country is: " & rb.SelectedItem.Text
end sub
</script>
<!DOCTYPE html>
<html>
<body>
<form runat="server">
<asp:RadioButtonList id="rb" runat="server"
AutoPostBack="True" onSelectedIndexChanged="displayMessage" />
<p><asp:label id="lbl1" runat="server" /></p>
</form>
</body>
</html>
运行结果:
Hashtable RadiobuttonList 2
<script runat="server">
sub Page_Load
if Not Page.IsPostBack then
dim navigate=New Hashtable
navigate.Add("RadioButtonList","control_radiobuttonlist.asp")
navigate.Add("CheckBoxList","control_checkboxlist.asp")
navigate.Add("DropDownList","control_dropdownlist.asp")
navigate.Add("ListBox","control_listbox.asp")
rb.DataSource=navigate
rb.DataValueField="Value"
rb.DataTextField="Key"
rb.DataBind()
end if
end sub
sub navigate(s as Object, e As EventArgs)
response.redirect(rb.SelectedItem.Value)
end sub
</script>
<!DOCTYPE html>
<html>
<body>
<form runat="server">
<asp:RadioButtonList id="rb" runat="server"
AutoPostBack="True" onSelectedIndexChanged="navigate" />
</form>
</body>
</html>
运行结果:
Hashtable DropDownList
<script runat="server">
sub Page_Load
if Not Page.IsPostBack then
dim mycountries=New Hashtable
mycountries.Add("N","Norway")
mycountries.Add("S","Sweden")
mycountries.Add("F","France")
mycountries.Add("I","Italy")
dd.DataSource=mycountries
dd.DataValueField="Key"
dd.DataTextField="Value"
dd.DataBind()
end if
end sub
sub displayMessage(s as Object,e As EventArgs)
lbl1.text="Your favorite country is: " & dd.SelectedItem.Text
end sub
</script>
<!DOCTYPE html>
<html>
<body>
<form runat="server">
<asp:DropDownList id="dd" runat="server"
AutoPostBack="True" onSelectedIndexChanged="displayMessage" />
<p><asp:label id="lbl1" runat="server" /></p>
</form>
</body>
</html>
运行结果:
创建 Hashtable
Hashtable 对象包含用键/值对表示的项目。键被用作索引,通过搜索键,可以实现对值的快速搜索。
通过 Add() 方法向 Hashtable 添加项目。
下面的代码创建了一个名为 mycountries 的 Hashtable 对象,并添加了四个元素:
<script runat="server">
Sub Page_Load
if Not Page.IsPostBack then
dim mycountries=New Hashtable
mycountries.Add("N","Norway")
mycountries.Add("S","Sweden")
mycountries.Add("F","France")
mycountries.Add("I","Italy")
end if
end sub
</script>
数据绑定
Hashtable 对象可为下列的控件自动生成文本和值:
- asp:RadioButtonList
- asp:CheckBoxList
- asp:DropDownList
-
asp:Listbox
为了绑定数据到 RadioButtonList 控件,首先要在 .aspx 页面中创建一个 RadioButtonList 控件(不带任何 asp:ListItem 元素):
<html>
<body>
<form runat="server">
<asp:RadioButtonList id="rb" runat="server" AutoPostBack="True" />
</form>
</body>
</html>
然后添加创建列表的脚本,并且绑定列表中的值到 RadioButtonList 控件:
<script runat="server">
sub Page_Load
if Not Page.IsPostBack then
dim mycountries=New Hashtable
mycountries.Add("N","Norway")
mycountries.Add("S","Sweden")
mycountries.Add("F","France")
mycountries.Add("I","Italy")
rb.DataSource=mycountries
rb.DataValueField="Key"
rb.DataTextField="Value"
rb.DataBind()
end if
end sub
</script>
<html>
<body>
<form runat="server">
<asp:RadioButtonList id="rb" runat="server" AutoPostBack="True" />
</form>
</body>
</html>
然后我们添加一个子例程,当用户点击 RadioButtonList 控件中的某个项目时,该子例程会被执行。当某个单选按钮被点击时,label 中会出现一行文本:
实例:
<script runat="server">
sub Page_Load
if Not Page.IsPostBack then
dim mycountries=New Hashtable
mycountries.Add("N","Norway")
mycountries.Add("S","Sweden")
mycountries.Add("F","France")
mycountries.Add("I","Italy")
rb.DataSource=mycountries
rb.DataValueField="Key"
rb.DataTextField="Value"
rb.DataBind()
end if
end sub
sub displayMessage(s as Object,e As EventArgs)
lbl1.text="Your favorite country is: " & rb.SelectedItem.Text
end sub
</script>
<html>
<body>
<form runat="server">
<asp:RadioButtonList id="rb" runat="server"
AutoPostBack="True" onSelectedIndexChanged="displayMessage" />
<p><asp:label id="lbl1" runat="server" /></p>
</form>
</body>
</html>
运行结果:
注释: 您无法选择添加到 Hashtable 的项目的排序方式。如需对项目进行字母排序或者数字排序,请使用 SortedList 对象。
下一篇:ASP.NET Web Forms 自学篇:(十二) SortedList 对象
上一篇:ASP.NET Web Forms 自学篇:(十) ArrayList 对象
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