使用hashtable实现的购物车 - 王朝网络宽屏版

在网上看到一些都不太好理解，所以把它们结合了一下，用HashTable去保存商品，再用DataTable写入到Datagrid中。http://61.180.163.222/shop

<%@ Page Language="VB" ContentType="text/html" Debug="true"%>

<%@ import namespace="system.data" %>

<%@ import namespace="system.data.oledb" %>

<html>

<head>

<title>无标题文档</title>

<!--

td {

font-size: 9pt;

line-height: 24px;

}

-->

</style>

<!--

a:link {

color: #000000;

text-decoration: none;

}

a:hover {

color: #FF0000;

text-decoration: none;

}

a:visited {

text-decoration: none;

}

-->

</style>

</head>

<tr>

<tr>

<p>您所选购的商品</p></td>

</tr>

<tr>

<td height="26"><asp:Datagrid ID="dgCar" runat="server"

autogeneratecolumns="false"

BorderColor="#000000"

BorderWidth="1"

CellPadding="3"

HeaderStyle-BackColor="#990000"

HeaderStyle-ForeColor="#FFFFFF"

DataKeyField="title_id"

<asp:boundcolumn HeaderText="商品" DataField="title" ItemStyle-Width="300"></asp:boundcolumn>

<asp:templatecolumn HeaderText="数量">

<asp:textbox size=1 id="Qty" runat="server"

text='<%# Databinder.eval(container.dataitem,"qty")%>'/>

</itemtemplate>

</asp:templatecolumn>

<asp:boundcolumn HeaderText="单价" DataField="price" DataFormatString="{0:c}"></asp:boundcolumn>

<asp:boundcolumn HeaderText="总计" DataField="total" DataFormatString="{0:c}"></asp:boundcolumn>

<asp:templatecolumn HeaderText="删除">

<asp:checkbox runat="server" ID="del"/>

</itemtemplate>

</asp:templatecolumn>

</columns>

</asp:Datagrid>

<asp:label runat="server" ID="msg" text="购物车为空" />

<hr>

<div align="right">总计:

<asp:label ID="lbltotal" runat="server" text="0"></asp:label>

<br>

折扣:<asp:label ID="sale" runat="server" Text="0.9"></asp:label><br>

应付:<asp:label ID="realprice" runat="server" Text="0" /></div>

<asp:imagebutton ID="re_car" ImageUrl="images/cxjs.gif" runat="server" OnClick="re_car_click" />

<asp:imagebutton ID="buy" ImageUrl="images/qsyt.gif" runat="server" />

<asp:imagebutton ID="clear" ImageUrl="images/qk.gif" runat="server" OnClick="clear_click" />

</tr>

<tr>

</tr>

</table></td>

</tr>

</table>

</form>

</body>

</html>

Sub Page_Load(Src As Object, E As EventArgs)

if not ispostback then

'取得用户要加入购物书的商品的ID

Dim product as string = request.QueryString("title-id")

'判断如果是用户所购买的第一件商品的话则那立一个hashTable

'否则从session中将已经存在的hashTable取回

Dim Hash As HashTable

IF Session("car") is nothing then

hash = New hashTable

Else

Hash = Session("car")

End if

'判断用户所选购的商品是否已经存在于购物车中

'如果不存在则将其加入购物车，如果存在则在原有数据上加1

if Not Hash.ContainsKey(product) then

Hash.Add(product,1)

else

hash.item(product) +=1

end if

session("car")=hash

display()

end if

End Sub

'------------------用于显示商品的子程序--------------------

Sub Display()

Dim i as integer

dim x as string

'取得session中的hashTable

dim hash as hashtable

Hash = Session("car")

'将所有选购的商品构造成为一个字符串

dim Products As String

products = "('"

For Each X in hash.keys

Products = products & X & "','"

Products = Products & "')"

'根据所购商品的字符串读取商品信息,然后放在producttable中

dim conn as oledbconnection

Dim ds as new dataset

dim Table1 as DataTable

dim connstr as string = "provider=Microsoft.jet.oledb.4.0;data source=" & server.MapPath("db3.mdb")

conn = new oledbconnection(connstr)

conn.open()

'读取数据并将数据填充到table1中

dim comm as oledbdataadapter

dim strsql as string ="select title_id,title,price from titles where title_id in " & products

comm = new oledbdataadapter(strsql,conn)

comm.fill(ds,"product")

table1 = ds.tables("product")

'向table1中增加一列

table1.columns.add(new datacolumn("qty",gettype(integer)))

'将title设置为主键

Dim Keys() as DataColumn = {table1.Columns("title_id")}

table1.primarykey=keys

'向producttable表新增字段

for each x in hash.keys

table1.rows.find(x).item("qty")=hash.item(x)

'向table1中增加总计列,并计算总计值

table1.columns.add(new datacolumn("total",gettype(double),"price*qty"))

'判断购物车是否为空

if table1.rows.count =0 then

dgcar.visible="false"

msg.visible="true"

else

dgcar.visible="True"

msg.visible="False"

end if

'计算帐单总价及折扣后的价格

lbltotal.text="0"

For i=0 to table1.rows.count-1

lbltotal.text =string.format("{0:c}",cdbl(lbltotal.text)+table1.rows(i).item("total"))

realprice.text = string.format("{0:c}",cdbl(sale.text) * lbltotal.text)

'将数据绑定dgcar

dgCar.datasource=table1.defaultview

dgCar.databind()

conn.close

End Sub

'------------------用于清空购物车的事件程序---------------

Sub clear_click(sender as object,e as imageclickeventargs)

'将session("car")清空

session("car") = new hashtable()

lbltotal.text = "0"

realprice.text="0"

display()

End sub

'------------------用于更新购物车的事件程序------------------

Sub re_car_click(sender as object,e as imageclickeventargs)

'判断Session("car")是否存在，如果在刚将其取得保存在hash中

Dim Hash As HashTable

IF Session("car") is nothing then

hash = New hashTable

Else

Hash = Session("car")

End if

'依决检查每一行的数量和checkbox控件，并更新hashtable

Dim qty As Textbox

dim del as checkbox

Dim I as integer

For I = 0 to dgcar.items.count -1

qty = dgcar.items(i).findcontrol("qty")

del = dgcar.items(i).findcontrol("del")

if (cint(qty.text)> 0) and (not del.checked) then

hash(dgcar.datakeys(i))=cint(qty.text)

else

hash.remove(dgcar.datakeys(i))

end if

display()

End sub

</script>