在.NET的Windows桌面应用中使用Amazon的Web Services

①      调用Amazon Web Service

引入Web Service成功后，编写代码将Amazon Web Service的名称空间引入

[C#]

using AmazonWebServices.com.amazon.soap;

[VB.NET]

Imports AmazonWebServices.com.amazon.soap

要实现SOAP查询，首先需要创建一个AmazonSearchService类的实例

[VB.NET]

Dim srch As New AmazonSearchService()

每次关键字查询都会需要创建KeywordRequest 实例；每次ASIN查询就需要创建一个AsinRequest对象。每次的请求也会返回一个ProductInfo的XML文档节点， 所以也必须创建一个ProductInfo实例从响应中检索ProductInfo的数据。

[VB.NET]

Dim kr As New KeywordRequest()

kr.devtag = "你得到的Amazon 开发者的证件"

kr.keyword = txtSearch.Text

kr.mode = "books"

kr.sort = "+titlerank"

kr.tag = "webservices-20"

kr.type = "lite"

kr.page = "1"

Dim pi As ProductInfo = srch.KeywordSearchRequest(kr)

Dim allDetails() As Details = pi.Details

请求发出之前需要将我们之前得到的Amazon 开发者证件的数值付给KeywordRequest 对象的devtag 属性，而结果会按照标题字母的升序排列。每次查询最多会返回10条数据，因此想要得到更多的数据必须进行多次查询。

[VB.NET]

If (pi.TotalResults > 10) Then

kr.page = "2"

pi = srch.KeywordSearchRequest(kr)

allDetails = pi.Details

End If

②      显示查询结果

[VB.NET]

Me.Cursor = Cursors.WaitCursor

Dim i As Int16

For i = 0 To allDetails.Length - 1

lstResults.Items.Add("产品名称：" & allDetails(i).ProductName & " || 产品序号：" & allDetails(i).Asin)

Next

Me.Cursor = Cursors.Default

③      显示明细

使用ListBox的SelectedIndexChanged事件检索ASIN（产品序号）请求的数据。

[VB.NET]

Dim ar As New AsinRequest()

ar.asin = Microsoft.VisualBasic.Right(CStr(lstResults.Items(lstResults.SelectedIndex)), Len(CStr(lstResults.Items(lstResults.SelectedIndex))) - (InStr(1, CStr(lstResults.Items(lstResults.SelectedIndex)), "|| 产品序号：") + Len("|| 产品序号：")) + 1)

ar.devtag = "你得到的Amazon 开发者的证件"

ar.type = "heavy"

ar.tag = "webservices-20"

Dim srch As New AmazonSearchService()

Dim pi As ProductInfo = srch.AsinSearchRequest(ar)

Dim allDetails() As Details = pi.Details

txtDetails.Text = "产品名称：" & allDetails(0).ProductName & System.Environment.NewLine

txtDetails.Text = txtDetails.Text & "产品序号：" & allDetails(0).Asin & System.Environment.NewLine

Dim strAuthors() As String = allDetails(0).Authors

If strAuthors.Length > 0 Then

Dim j As Int16

For j = 0 To strAuthors.Length - 1

txtDetails.Text = txtDetails.Text & "作者：" & strAuthors(j) & System.Environment.NewLine

Next

End If

txtDetails.Text = txtDetails.Text & "分类：" & allDetails(0).Catalog & System.Environment.NewLine

txtDetails.Text = txtDetails.Text & "出版商：" & allDetails(0). Publisher & System.Environment.NewLine

txtDetails.Text = txtDetails.Text & "数量：" & allDetails(0).CollectibleCount & System.Environment.NewLine

txtDetails.Text = txtDetails.Text & "价格：" & allDetails(0).CollectiblePrice & System.Environment.NewLine

txtDetails.Text = txtDetails.Text & "小图片URL：" & allDetails(0).ImageUrlSmall & System.Environment.NewLine

txtDetails.Text = txtDetails.Text & "中图片URL：" & allDetails(0).ImageUrlMedium & System.Environment.NewLine

txtDetails.Text = txtDetails.Text & "大图片URL：" & allDetails(0).ImageUrlLarge & System.Environment.NewLine

④      显示URL指向的图片

从上面代码的最后几行可以看到每个产品是含有图片的，我们可以自己编写一个ImageFromAmazon方法用来显示Amazon网站上面的图片信息。

    Private Function ImageFromAmazon(ByVal url As String) As Image

        Dim wc As New WebClient()

        Dim st As System.IO.Stream = wc.OpenRead(url)

        Dim img As Image = Image.FromStream(st)

        st.Close()

        Return img

    End Function

ImageFromAmazon方法创建WebClient实例并从指定的URL请求图片数据分配给Stream对象，方法的返回值是Image类型，这种类型可以直接赋值给PictureBox的Image属性。那么在现有的窗体上面加入PictureBox控件，然后编写如下代码放到ListBox的SelectedIndexChanged事件的最后，就能够实现显示URL图片的功能了。

[VB.NET]

pbImage.Image = ImageFromAmazon(allDetails(0).ImageUrlMedium)