ASP.NET - The Hashtable Object

The Hashtable//散列表 object//对像 contains items in key/value pairs//对.

Examples

Example 1 - Hashtable RadioButtonList//单选按钮列表

ASPX Source:

<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>

Output Result:


 
 if you click the radio "Norway",it will shows:

Your favorite country is: Norway

 

Example 2 - Hashtable RadiobuttonList

ASPX Source:
<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>

<html>
<body>

<form runat="server">
<asp:RadioButtonList id="rb" runat="server"
AutoPostBack="True" onSelectedIndexChanged="navigate" />
</form>

</body>
</html>

Output Result:
 

if you click the radio "DropDownList",It will show:

it will open the file "control_dropdownlist.asp" in the frame of Output Result.

Example 3
 
- Hashtable DropDownList//下拉菜单式列表

ASPX Source:

<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>

<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>

Output Result:

 

it you click the dropDownList "Italy"

Your favorite country is: Italy

 

Create a Hashtable

The Hashtable object contains items in key/value pairs//关键字/值成对出现. The keys are used as indexes//索引, and very quick searches can be made for//用于 values by searching through their keys.

Items are added to the Hashtable with the Add() method.

The following code creates a Hashtable//散列表 named mycountries and four elements//四个元素 are added:

<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>

Data Binding

A Hashtable object //散列表对像may automatically generate the text and values//文本和值 to the following controls://控件

  • asp:RadioButtonList //单选按钮
  • asp:CheckBoxList //多选框
  • asp:DropDownList //下拉式列表
  • asp:Listbox //列表框

To bind //绑定data to a RadioButtonList control, first create a RadioButtonList control (without any asp:ListItem elements) in an .aspx page:

<html>
            <body>
<form runat="server">
            <asp:RadioButtonList id="rb" runat="server"
            AutoPostBack="True" />
</form>
</body>
            </html>

Then add the script that builds the list://创建列表

<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>

Then we add a sub routine//子程序 to be executed when the user clicks on an item in the RadioButtonList control. When a radio button is clicked, a text will appear in a label:

<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>

Note: You cannot choose the sort order//排序 of the items added to the Hashtable. To sort items alphabetically//按字母表顺序地 or numerically//数值, use the SortedList//分类列表 object.

posted on 2007-01-19 17:13  改变热爱  阅读(222)  评论(0)    收藏  举报

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