随手写了个京东发票助手

因为需要批量下载京东的电子发票，随手用VB .NET写了个WinForm小工具，为了图省事通过 WebBrowser 结合 WebClient 实现了“半自动”的下载，一次要下载很多发票时能省不少力气。

比较值得记下来的几个卖点：

1.共享Cookie，实现 WebClient 下载 WebBrowser 中选定的链接

    ''' <summary>
    ''' 下载保存文件
    ''' </summary>
    ''' <param name="url"></param>
    Private Shared Sub saveFile(ByVal url As String, doc As HtmlDocument)
        Dim strCookies As String = doc.Cookie
        'If String.IsNullOrEmpty(strCookies) Then
        '    strCookies = CookieHelper.GetCookieString(url)
        'End If
        Try
            Using wc As New Net.WebClient
                wc.Headers.Add("Cookie", strCookies) '共享 WebBrowser.Cookie
                wc.DownloadFile(url, getFilename(url))
            End Using
        Catch ex As Exception
            Stop
        End Try
    End Sub

2.查找页面元素，实现自动点击

    Private Shared Function findElement(ByVal doc As HtmlDocument, ByVal elementId As String) As HtmlElement
        Dim ret As HtmlElement = Nothing
        Try
            ret = doc.GetElementById(elementId)
        Catch ex As Exception
            Debug.Print("findElement err:{0}", ex.Message)
        End Try

        Return ret
    End Function

    Private Shared Function findElement(doc As HtmlDocument, ByVal href As String, ByVal innerText As String) As HtmlElement
        Dim ret As HtmlElement = Nothing
        For Each element As HtmlElement In doc.Links
            If element.InnerText = innerText AndAlso element.GetAttribute("href") = href Then
                ret = element
                Exit For
            End If
        Next
        Return ret
    End Function

    '通过 InvokeMember 触发点击动作
    _currElemet = findElement(wb.Document, url, "发票详情")
    If _currElemet IsNot Nothing Then
        _currElemet.InvokeMember("click")
    Else
        Debug.Print("findElement NOT FOUND " & url)
    End If