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Version3 User Controls For Amazon.com
books
by Charles Carroll
This page demonstrates a very useful
in the real-world
User Control to encapsulate a hyperlink and book cover to buy something from Amazon.com
and to use one's promotional code to make a little money on the deal.
Simple page:
filename=/experiments/usercontrols/testbooks_v3.aspx
<%@ Trace="true" debug="true" %>
<%@ Register TagPrefix="bookshow" tagname="cover" src="books_v3.ascx"%>
<html><head>
<title>CodeShow Test</title>
</head>
<body>
<bookshow:cover ISBN="0201485672"
promocode="learnasp" AmazonDevToken="D1967KF255R5KZ"
ShowDetails="ProductName,ListPrice,OurPrice,UsedPrice,Author,AvgCustomerRating"
height=105 width=80 runat="server"/><br>
<bookshow:cover ISBN="0517887290"
promocode="learnasp" AmazonDevToken="D1967KF255R5KZ"
ShowDetails="ProductName,ListPrice,OurPrice,UsedPrice,Author,AvgCustomerRating"
height=105 width=80 runat="server"/><br>
<bookshow:cover ISBN="0385484992"
promocode="learnasp" AmazonDevToken="D1967KF255R5KZ"
ShowDetails="ProductName,ListPrice,OurPrice,UsedPrice,Author,AvgCustomerRating"
height=105 width=80 runat="server"/><br>
<bookshow:cover ISBN="0451169530" promocode="easterseals" height=105 width=80 runat="server"/><br>
<bookshow:cover ISBN="0553283685"
promocode="learnasp" AmazonDevToken="D1967KF255R5KZ"
ShowDetails="All"
height=105 width=80 runat="server"/><br>
<bookshow:cover ISBN="B0000797E5"
promocode="learnasp" AmazonDevToken="D1967KF255R5KZ"
ShowDetails="All"
height=105 width=80 runat="server"/><br>
</body>
</html>
The User Control:
filename=/experiments/usercontrols/books_v3.ascx
<%@ debug="true" %>
<%@import namespace="system.io"%>
<%@import namespace="system.net"%>
<%@import namespace="system.xml"%>
<%@import namespace="System.Security.Cryptography"%>
<script runat="server" language="vb">
Public isbn AS string ' rainbow item only
public localGraphic as string ' rainbow item only
Public height AS integer=80 ' rainbow item, module can set default*
Public width as integer=55 ' rainbow item, module can set default*
public AmazonDevToken as string ' rainbow item, module can set default*
public showDetails as string="ProductName,OurPrice,UsedPrice,Author,Actor,Director,MPAARating,TheatricalReleaseDate,AvgCustomerRating,Artist,ReleaseDate,Track" ' rainbow item, module can set default*
public promocode as string="learnasp" ' rainbow item, module can set default*
' ~/Amazon.config should be checked for defaults, then module, then item
Sub Page_Load(Src As Object, E As EventArgs)
Trace.TraceMode = TraceMode.SortByTime
book.NavigateUrl="http://www.amazon.com/exec/obidos/ISBN=" & ISBN & "/" & promocode
IF len(localgraphic)=0 THEN
bookcover.ImageURL="http://images.amazon.com/images/P/" & ISBN & ".01.MZZZZZZZ.jpg"
ELSE
bookcover.ImageURL=localgraphic
END IF
bookcover.Alternatetext="Amazon:" & isbn
bookcover.height=Unit.Pixel(height)
bookcover.width=Unit.pixel(width)
If ShowDetails.Length>0
dim strAmazonURL as string="http://xml.amazon.com/onca/xml2?"
strAmazonURL &= "t=" & PromoCode & "&dev-t=" & AmazonDevToken
strAmazonURL &= "&type=heavy&AsinSearch=" & isbn & "&f=xml"
DIM xmlTr1 as XmlTextReader
xmlTr1=XMLReaderCached_v2(strAmazonURL)
LitBookDetails.Text="<br>"
ShowDetails="," & ShowDetails & ","
DO WHILE xmlTr1.Read()
if xmlTr1.NodeType.ToString()="Element"
dim strName as string=xmlTr1.Name
if showDetails.IndexOf("," & strName & ",")>-1 OR showDetails.tolower()=",all,"
xmlTr1.Read()
'trace.write("isemptyelement;hasvalue;name;typename;length", xmltr1.IsEmptyElement() & ";" & xmltr1.HasValue() & ";" & strName & ";" & typename(xmlTr1.value) & ";" & Xmltr1.value.length())
LitBookDetails.Text &= strName & " <b>" & xmlTr1.Value & "</b><br>"
End if
end if
LOOP
end if
End Sub
private function XmlReaderCached_v1(strXML as string) as XmlTextReader
dim xmlTrCached as new XmlTextReader(strXML)
return(xmlTrCached)
end function
private function XmlReaderCached_v2(strXML as string) as XmlTextReader
dim xmlTrCached as XmlTextReader
Dim strChksum As String=MD5checksum(strXML)
Dim strInCache as string
If Cache(strChksum) Is Nothing Then
trace.write("cache miss",strXML)
strInCache=httpGet(strXML)
If strInCache="error"
' nothing to do
else
Cache.Insert(strChksum,strInCache,Nothing,DateTime.Now.AddMinutes(10), Cache.NoSlidingExpiration)
end if
Else
trace.write("cache hit",strXML)
strInCache=Cache(strChksum)
End If
dim strReader1 as StringReader= new StringReader(strInCache)
xmlTrCached=new XmlTextReader(strReader1)
return(xmlTrCached)
end function
private function httpget(strURL as string) as string
dim sr1 as streamreader
dim strTemp as string
Dim webResponse1 As WebResponse
Dim webRequest1 As WebRequest
TRY
webRequest1 = webRequest1.Create(strURL)
webResponse1 = webRequest1.GetResponse()
sr1 = New StreamReader(webResponse1.GetResponseStream())
strTemp=sr1.ReadToEnd()
CATCH exc1 as exception
strTemp="error"
FINALLY
sr1.Close
END TRY
return(strTemp)
end function
Private Function ConvertStr2ByteArray(ByVal strInput As String) As Byte()
Dim intCounter As Integer
Dim arrChar As Char()
arrChar = strInput.ToCharArray()
Dim arrByte(arrChar.Length - 1) As Byte
For intCounter = 0 To arrByte.Length - 1
arrByte(intCounter) = Convert.ToByte(arrChar(intCounter))
Next
Return arrByte
End Function
private Function MD5checksum(ByVal strParm1 As String) As String
Dim arrHashInput As Byte()
Dim arrHashOutput As Byte()
Dim objMD5 As new MD5CryptoServiceProvider
arrHashInput = ConvertStr2ByteArray(strParm1)
arrHashOutput = objMD5.ComputeHash(arrHashInput)
return(BitConverter.ToString(arrHashOutput))
End Function
</script>
<asp:hyperlink id="book" runat="server">
<asp:Image ID="bookcover" runat="server" />
</asp:hyperlink>
<asp:Literal id="litBookDetails" runat="server"/>
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a $5 tip buys him lunch at McDonalds,
a $20 tip buys his kid Hitoshi a new computer game,
a $39 tip buys his daughter Michiko a few nice outfits.
See our donor list.
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