创建无 Excel 对象的动态饼图并导出到 Excel 文件

引言

既然您已经知道如何从 ASP.NET Web 页面创建简单的图像，那么您可以创建更复杂（和更有用）的图像。 在本文的剩余部分中，我将研究如何使用 .NET Framework 绘图类从数据库信息创建饼图。 我会将所有这些功能构建到 ASP.NET Web 页面中的一组函数中，这些函数最终会将动态创建的饼图的二进制内容流式传输到 Response 对象的 OutputStream。

虽然创建一组页面级函数来显示饼图可以完成手头的任务，但更具可重用性的解决方案是将此功能封装到自定义的 ASP.NET Web 控件或编译的自定义控件中。 然而，这种方法的一个缺点是，自定义的 ASP.NET Web 控件或编译的自定义控件必须将图像的文件保存到 Web 服务器的文件系统中，然后从适当的 img 标记呈现它。 虽然这并不难实现，但您必须处理我前面提到的缺点，包括每次生成图表时，您都会不断添加到 Web 服务器文件系统上的图像列表中。

用于创建 ASPX 页面的 CreatePieChart 函数

1. 创建另一个 ASPX 页面，例如 (testintvsoffer.aspx)
   在此页面上，拖放一个数据网格和一个按钮

   按钮的名称是 btnTransferToXls。

   Region "On Click Button Transfer To Xls "
   
   Private Sub btnTransferToXls_Click(ByVal sender As System.Object, _
           ByVal e As System.EventArgs) Handles btnTransferToXls.Click
   
       Try
           Dim strDateFrom, strDateTo As String
           strDateFrom = txtDateFrom.Text
           strDateTo = txtDateTo.Text
           Dim dtStart As Date
           Dim dtEnd As Date
   
           Session("Dtbl") = dtblIntVoffer
       Catch ex As Exception
           lblMessage.Text = ex.Message
       End Try
   
       Dim TblRcount As Int64
       'Dim dg As New DataGrid
       Dim dtblExport As New DataTable
   
       If Not IsNothing(Session("Dtbl")) Then
           dtblExport = CType(Session("Dtbl"), DataTable)
           TblRcount = dtblExport.Rows.Count
       End If
   
       Try
           'dtblIntVoffer = GetData()
           If TblRcount > 0 Then
               lblMessage.Text = ""
               Dg2.Dispose()
               Dg2.DataSource = dtblExport
               Dg2.DataBind()
   
   
               'Here we add code for call
               'delegates same handle dg_itembound()
               'AddHandler Dg2.ItemDataBound,
               ' AddressOf Dg2_ItemDataBound
   
               Dg2.HeaderStyle.BackColor = Color.LightGray
               Dg2.HeaderStyle.Font.Bold = True
   
               Dg2.ShowFooter = True
               Dg2.ItemStyle.BackColor = Color.White
   
               ' Set the content type to Excel.
               Response.ContentType = "application/vnd.ms-excel"
               Response.AddHeader("content-disposition", _
                 "attachment;filename=InterviewVsOffer.xls")
               Response.Charset = ""
   
               ' Turn off the view state.
               Me.EnableViewState = False
   
               Dim tw As New System.IO.StringWriter
               Dim hw As New System.Web.UI.HtmlTextWriter(tw)
   
               ' Get the HTML for the control.
               Dg2.RenderControl(hw)
               ' Write the HTML back to the browser.
               Response.Clear()
               Response.Write(tw.ToString())
               'End the response.
               Response.End()
               'Server.Execute("frmcharts.aspx")
           Else
               lblMessage.Text = "No Records Found"
               Exit Sub
           End If
       Catch ex As Exception
           lblMessage.Text = "Error in Exporting to Excel"
       Finally
           Dg2.Dispose()
           Dg2.DataSource = Nothing
       End Try
   End Sub
   
   #End Region
   
   #Region "On Item Data Bound Of DataGrid 2 "
   
   Private Sub Dg2_ItemDataBound(ByVal sender As Object, _
           ByVal e As System.Web.UI.WebControls.DataGridItemEventArgs) _
           Handles Dg2.ItemDataBound
       Dim rColor, gColor, bColor As Int16
       rColor = 255
       gColor = 0
       bColor = 255
   
       If e.Item.ItemType = ListItemType.Header Then
           Dim HedText As Int32
           For HedText = 18 To 49
               If HedText <= 33 Then
                   e.Item.Cells(HedText).Text = _
                     e.Item.Cells(HedText).Text.Replace("1", "")
               Else
                   e.Item.Cells(HedText).Text = _
                     e.Item.Cells(HedText).Text.Replace("2", "")
               End If
           Next
   
           e.Item.Cells(1).Text = e.Item.Cells(1).Text.Replace("1", "")
           Dim dgItem As DataGridItem
           Dim dgCell As TableCell
           dgItem = New DataGridItem(0, 0, ListItemType.Footer)
           dgCell = New TableCell
           dgCell.ColumnSpan = 2
           dgItem.Cells.Add(dgCell)
           dgCell.Text = "Months"
           dgCell.BackColor = _
             System.Drawing.ColorTranslator.FromOle(RGB(rColor, _
             gColor, bColor))
           dgCell.ForeColor = _
             System.Drawing.ColorTranslator.FromOle(RGB(r1Color, _
             g1Color, b1Color))
           dgCell.HorizontalAlign = HorizontalAlign.Center
           'Dg1.Controls(0).Controls.AddAt(0, dgItem)
   
           'dgItem = New DataGridItem(0, 0, ListItemType.Footer)
           dgCell = New TableCell
           dgCell.ColumnSpan = 16
           dgItem.Cells.Add(dgCell)
           dgCell.Text = "Interview"
           dgCell.BackColor = _
             System.Drawing.ColorTranslator.FromOle(RGB(rColor, _
             gColor, bColor))
           dgCell.ForeColor = _
             System.Drawing.ColorTranslator.FromOle(RGB(r1Color, _
             g1Color, b1Color))
           dgCell.HorizontalAlign = HorizontalAlign.Center
   
           dgCell = New TableCell
           dgCell.ColumnSpan = 16
           dgItem.Cells.Add(dgCell)
           dgCell.Text = "Offers"
           dgCell.BackColor = _
             System.Drawing.ColorTranslator.FromOle(RGB(rColor, _
             gColor, bColor))
           dgCell.ForeColor = _
             System.Drawing.ColorTranslator.FromOle(RGB(r1Color, _
             g1Color, b1Color))
           dgCell.HorizontalAlign = HorizontalAlign.Center
   
           dgCell = New TableCell
           dgCell.ColumnSpan = 16
           dgItem.Cells.Add(dgCell)
           dgCell.Text = "Joinees"
           dgCell.BackColor = _
             System.Drawing.ColorTranslator.FromOle(RGB(rColor, _
             gColor, bColor))
           dgCell.ForeColor = _
             System.Drawing.ColorTranslator.FromOle(RGB(r1Color, _
             g1Color, b1Color))
           dgCell.HorizontalAlign = HorizontalAlign.Center
   
           Dg2.Controls(0).Controls.AddAt(0, dgItem)
   
       End If
   
       Dim intColCounter, ColTotal, CfinalTotal As Integer
       Dim intRowCounter As Integer
       Dim Itotal, Ototal, Jtotal As Integer
       Dim i As Int64
       Dim PerTotal As Double
       i = 1
       Dim cnt As Integer = Dg2.Items.Count + 3
       If e.Item.ItemType = ListItemType.Footer Then
           Dim dgItem2 As DataGridItem
           Dim dgItem3 As DataGridItem
           Dim dgCell1 As TableCell
           Dim dgCell2 As TableCell
           Dim dgCell3 As TableCell
   
           dgItem2 = New DataGridItem(cnt, cnt, ListItemType.Footer)
   
           dgCell2 = New TableCell
           dgCell2.ColumnSpan = 2
           dgItem2.Cells.Add(dgCell2)
           dgCell2.Text = "Pie-Graph"
           dgCell2.ForeColor = Color.Red
           dgCell2.Font.Bold = True
   
           Dim Intviewtoatal As Double
           Dim Offertoatal As Double
           Dim Joineestoatal As Double
   
           For intRowCounter = 0 To Dg2.Items.Count - 1
   
               Intviewtoatal = Intviewtoatal + _
                 CInt(Dg2.Items(intRowCounter).Cells(17).Text)
               Offertoatal = Offertoatal + _
                 CInt(Dg2.Items(intRowCounter).Cells(33).Text)
               Joineestoatal = Joineestoatal + _
                 CInt(Dg2.Items(intRowCounter).Cells(49).Text)
   
           Next
   
           For intColCounter = 2 To 49
               CfinalTotal = 0
   
               For intRowCounter = 0 To Dg2.Items.Count - 1
                   ColTotal = _
                     CInt(Dg2.Items(intRowCounter).Cells(intColCounter).Text)
                   CfinalTotal = CfinalTotal + ColTotal
               Next
   
               If (intColCounter <= 17 And Intviewtoatal > 0) Then
   
                   ' PerTotal = CInt((CfinalTotal / Intviewtoatal) * 100)
                   PerTotal = Convert.ToDouble_
                   ((CfinalTotal / Intviewtoatal) * 100)
                   PerTotal = (PerTotal.ToString("N", nfi))
               ElseIf (intColCounter <= 33 And Offertoatal > 0) Then
   
                   ' PerTotal = CInt((CfinalTotal / Offertoatal) * 100)
                   PerTotal = Convert.ToDouble_
                   ((CfinalTotal / Offertoatal) * 100)
                   PerTotal = (PerTotal.ToString("N", nfi))
               ElseIf (intColCounter > 33 And Joineestoatal > 0) Then
                   ' PerTotal = CInt((CfinalTotal / Joineestoatal) _
                   '  * 100) PerTotal = Convert.ToDouble((CfinalTotal _
                   '  / Joineestoatal) * 100)
                   PerTotal = (PerTotal.ToString("N", nfi))
               Else
                   PerTotal = 0
               End If
   
               dgCell = New TableCell
               dgcell.Text = CfinalTotal
               dgItem.Cells.Add(dgCell)
               Dg2.Controls(0).Controls.AddAt(cnt, dgItem)
   
               dgCell1 = New TableCell
               dgCell1.Text = PerTotal
               dgItem1.Cells.Add(dgCell1)
               Dg2.Controls(0).Controls.AddAt(cnt + 1, dgItem1)
   
           Next
   
           dgCell3 = New TableCell
           'dgCell3.Text = PerTotal
           dgCell3.ColumnSpan = 10
           dgItem3.Cells.Add(dgCell3)
           Dg2.Controls(0).Controls.AddAt(cnt + 2, dgItem3)
   
           'This code for Get the Graph from another page and
           'integrate with datagrid that together export to Excel
           'New Code Add for Maintain Global Tem Table
           'for same session or conn for one user
           'clsCon.OpenCon_
           '(ConfigurationSettings.AppSettings("strConnection").ToString)
           'SQLSTR = "select RefType,total from CanEnter "
   
           Dim sqlstr As String
           Dim oleAdap As OleDbDataAdapter
           Dim ds1 As DataSet
           Dim Int As Int64
   
           sqlstr = "select ROWNUM Rowcnt,RefType,total," & _
                    "totalper from TABLE order by ROWNO "
   
           oleAdap = New OleDbDataAdapter(sqlstr, clsCon.Con)
           ds1 = New DataSet
           oleAdap.Fill(ds1)
           Session("ds1") = ds1
   
           clsCon.closeCon()
   
           'End New Code Add for Maintain Global Tem Table
           'for same session or conn for one user
   
           Dim Img As New System.Web.UI.WebControls.Image
           ' This code of line executes the page on the
           ' server side and gets the output to this page
           Server.Execute("frmCharts.aspx")
           Dim strFilePath As String
           'strFilePath = Server.MapPath(".") & "/Images/Graph.gif"
           'Response.Write(Server.MapPath("."))
           'strFilePath = "http://RemotServer IP Address
           '            /ProjectName/Images/Graph.gif"
           Dim strPath, struser As String
           strPath = "http://" & Request.ServerVariables("server_name") _
                     & Request.ServerVariables("script_name").ToLower().Trim
           struser = Session("login")
           strPath = Strings.Replace(strPath, ("testintvsoffer.aspx"), _
                     "Graphs/") & struser & ".gif"
   
           Img.ImageUrl = strPath
           ' Img.ImageUrl = "d:/deep/test1.gif"
           dgCell2 = New TableCell
           dgCell2.Controls.Add(Img)
           dgItem2.Cells.Add(dgCell2)
           Dg2.Controls(0).Controls.AddAt(cnt + 3, dgItem2)
   
           'End This code for getting the Graph from another page
           'and integrate with datagrid that together exports to Excel
   
           'Dim lc As LiteralControl
           'lc.Text = "Deepchand"
           'Dg2.Controls.Add(lc)
           'Dg2.Controls(0).Controls.AddAt(cnt + 2, dgItem1)
   
           i = i + 1
       End If
   End Sub
   
   #End Region

2. 为此创建另一个 ASPX 页面，它将根据用户会话创建饼图

   创建一个 frmCharts.aspx 文件并编写以下代码

   此代码将根据您从数据库中获取的数据值生成饼图。

   'Imports these Namespaces
   Imports System.Data.OleDb
   Imports System.Data
   Imports System.Drawing
   Imports System.Drawing.Imaging
   Imports System.Math
   
   '******************************************
   Public Class frmCharts Inherits System.Web.UI.Page
   
   #Region "Global VAriable Declarations "
   
       Dim clsCon As New conn
       Dim SQLSTR As String
       Dim ds1 As New DataSet
       Dim oleAdap As New OleDbDataAdapter
       Dim Int As Integer
       Dim Total As Double
   
   #End Region
   
   #Region " On Page Load "
       Dim ds2 As DataSet
       ds2 = New DataSet
       Try
           ds1.Clear()
           If Not IsNothing(Session("ds1")) Then
               ds2 = CType(Session("ds1"), DataSet)
               Int = ds2.Tables(0).Rows.Count
               Session("ds1") = Nothing
           End If
       Catch ex As Exception
       Finally
           clsCon.closeCon()
       End Try
   
       'Build an array of values for the bar and pie chart.
       'These values could also be pulled from a database.
       Dim arrValues(4) As Integer
       Dim str1, str2 As String
       'Declare your object variables
       'Build a BitMap that will act as the pallet
       'and container for the bar graph. Here 600 is
       'the width and 300 is the height.
       'These values could also be passed as parameters.
       Dim i As Integer
       Dim objBitMap As New Bitmap(960, 660)
   
       'Declare your Graphics objects for painting
       'graphics on your newly created bitmap.
       Dim objGraphics As Graphics
       objGraphics = Graphics.FromImage(objBitMap)
       'Set the background color to LightGray
       objGraphics.Clear(Color.LightGray)
       'Write out a title for your bar and pie chart.
       objGraphics.DrawString("Interview Vs Offer Report", _
         New Font("Verdana", 16), Brushes.Black, _
         New PointF(280, 5))
       objGraphics.DrawString("Interview Graph", _
         New Font("Verdana", 12, FontStyle.Bold), _
         Brushes.Black, New PointF(5, 35))
       objGraphics.DrawString("Interview Sources", _
         New Font("Verdana", 12, FontStyle.Bold), _
         Brushes.Black, New PointF(360, 45))
       ' objGraphics.DrawString("Offer Graph", _
       '    New Font("Verdana", 12, FontStyle.Bold), _
       '    Brushes.Black, New PointF(5, 250))
       ' objGraphics.DrawString("Joinees Graph", _
       '    New Font("Verdana", 12, FontStyle.Bold), _
       '    Brushes.Black, New PointF(5, 450))
       objGraphics.DrawString("Joinees Sources", _
       '    New Font("Verdana", 12, FontStyle.Bold), _
       '    Brushes.Black, New PointF(360, 345))
       objGraphics.DrawString("Offer Sources", _
            New Font("Verdana", 12, FontStyle.Bold), _
            Brushes.Black, New PointF(640, 45))
       ' objGraphics.DrawRectangle(Pens.Red, 2, 2, 900, 925)
       ' objGraphics.DrawLine(Pens.YellowGreen, 270, 40, 270, 700)
       'Inter Rectangle
       objGraphics.DrawRectangle(Pens.Red, 280, 40, 340, 300)
       objGraphics.FillRectangle(Brushes.WhiteSmoke, _
                                 281, 65, 338, 265)
       'Offer Rectangle
       objGraphics.DrawRectangle(Pens.Red, 280, 340, 340, 300)
       objGraphics.FillRectangle(Brushes.WhiteSmoke, _
                                 281, 365, 338, 265)
       'Joinees Rectangle
       objGraphics.DrawRectangle(Pens.Red, 600, 40, 340, 300)
       objGraphics.FillRectangle(Brushes.WhiteSmoke, _
                                 601, 65, 338, 265)
       'Create a legend Text to describe your bar and chart.
   
       Dim symbolLeg As PointF = New PointF(300, 80)
       Dim descLeg As PointF = New PointF(335, 76)
       Dim descLeg1 As PointF = New PointF(540, 76)
       Dim symbolLeg1 As PointF = New PointF(300, 380)
       Dim descLeg2 As PointF = New PointF(335, 376)
       Dim descLeg3 As PointF = New PointF(540, 376)
       Dim symbolLeg2 As PointF = New PointF(620, 80)
       Dim descLeg4 As PointF = New PointF(655, 76)
       Dim descLeg5 As PointF = New PointF(860, 76)
   
       Try
           For i = 0 To 46
               str1 = ds2.Tables(0).Rows(i).Item(1)
               str2 = ds2.Tables(0).Rows(i).Item(3) & "%"
               If i = 0 Or i = 16 Or i = 32 Then
                   str1 = "Consultant"
               ElseIf i = 1 Or i = 17 Or i = 33 Then
                   str1 = "Employee Referral"
               ElseIf i = 2 Or i = 18 Or i = 34 Then
                   str1 = "Management Referral"
               ElseIf i = 3 Or i = 19 Or i = 35 Then
                   str1 = "Ex Employee Referral"
               ElseIf i = 4 Or i = 20 Or i = 36 Then
                   str1 = "Walk In"
               ElseIf i = 5 Or i = 21 Or i = 37 Then
                   str1 = "Institution"
               ElseIf i = 6 Or i = 22 Or i = 38 Then
                   str1 = "Web"
               ElseIf i = 7 Or i = 23 Or i = 39 Then
                   str1 = "Advertising"
               ElseIf i = 8 Or i = 24 Or i = 40 Then
                   str1 = "Recruitment Team Effort"
               ElseIf i = 9 Or i = 25 Or i = 41 Then
                   str1 = "Telecalling "
               ElseIf i = 10 Or i = 26 Or i = 42 Then
                   str1 = "Campus"
                   If i <= 14 Then
                       objGraphics.FillRectangle(New SolidBrush(GetColor(i)),_
                                   symbolLeg.X, symbolLeg.Y, 20, 10)
                       objGraphics.DrawRectangle(Pens.Black, _
                              symbolLeg.X, symbolLeg.Y, 20, 10)
                       objGraphics.DrawString(str1.ToString, _
                         New Font("Verdana", 10, FontStyle.Bold), _
                         Brushes.Black, descLeg)
                       objGraphics.DrawString(str2.ToString, _
                         New Font("Verdana", 10, FontStyle.Bold), _
                         Brushes.Blue, descLeg1)
                       symbolLeg.Y += 15
                       descLeg.Y += 15
                       descLeg1.Y += 15
                   ElseIf i <= 30 And i > 15 Then
                       objGraphics.FillRectangle(New SolidBrush(GetColor(i)), _
                         symbolLeg2.X, symbolLeg2.Y, 20, 10)
                       objGraphics.DrawRectangle(Pens.Black, _
                         symbolLeg2.X, symbolLeg2.Y, 20, 10)
                       str1 = Replace(str1, "1", "")
                       objGraphics.DrawString(str1.ToString, _
                         New Font("Verdana", 10, FontStyle.Bold), _
                         Brushes.Black, descLeg4)
                       objGraphics.DrawString(str2.ToString, _
                         New Font("Verdana", 10, FontStyle.Bold), _
                         Brushes.Blue, descLeg5)
                       symbolLeg2.Y += 15
                       descLeg4.Y += 15
                       descLeg5.Y += 15
                   ElseIf i > 31 Then
                       objGraphics.FillRectangle(New _
                         SolidBrush(GetColor(i)), symbolLeg1.X, _
                         symbolLeg1.Y, 20, 10)
                       objGraphics.DrawRectangle(Pens.Black, _
                         symbolLeg1.X, symbolLeg1.Y, 20, 10)
                       str1 = Replace(str1, "2", "")
                       objGraphics.DrawString(str1.ToString, _
                         New Font("Verdana", 10, FontStyle.Bold), _
                         Brushes.Black, descLeg2)
                       objGraphics.DrawString(str2.ToString, _
                         New Font("Verdana", 10, FontStyle.Bold), _
                         Brushes.Blue, descLeg3)
                       symbolLeg1.Y += 15
                       descLeg2.Y += 15
                       descLeg3.Y += 15
               End If
           Next
   
           'Loop through the values to create the Pie Chart.
   
           Dim sglCurrentAngle As Single = 0
           Dim sglTotalAngle As Single = 0
           Dim sglCurrentAngle1 As Single = 0
           Dim sglTotalAngle1 As Single = 200
           i = 0
   
           For i = 0 To 14
               str1 = ds2.Tables(0).Rows(i).Item(2)
               str2 = ds2.Tables(0).Rows(i).Item(2)
               Dim Value As Double
               Value = Convert.ToDouble(str2)
               Total = Total + Value
           Next
   
           Dim xAxis As Double, yAxis As Double
               'For i = 0 To ds2.Tables(0).Rows.Count - 1
               For i = 0 To 14
                   str1 = ds2.Tables(0).Rows(i).Item(3)
                   str2 = ds2.Tables(0).Rows(i).Item(2)
                   Dim Value As Double
                   Dim Value1 As Double
                   Value = Convert.ToDouble(str2)
                   Value1 = Convert.ToDouble(str1)
                   'Current Value / (sum of all the Values) _
                   '        * 360 degree angle
                   sglCurrentAngle = Convert.ToSingle(Value / Total * 360)
                   objGraphics.FillPie(New SolidBrush(GetColor(i)), _
                     100, 80, 100, 100, sglTotalAngle, sglCurrentAngle)
                   sglTotalAngle += sglCurrentAngle
                   sglTotalAngle1 += sglCurrentAngle1
               Next i
               '*** End This loop only for those into
               sglTotalAngle = 0
               sglCurrentAngle = 0
               Total = 0
   
               For i = 32 To 46
                   str1 = ds2.Tables(0).Rows(i).Item(2)
                   str2 = ds2.Tables(0).Rows(i).Item(2)
                   Dim Value As Double
                   Value = Convert.ToDouble(str2)
                   Total = Total + Value
               Next
   
           Catch ex As Exception
       Finally
           ds2.Clear()
       End Try
       'This Old code line responsed output as image save as output
   
       'objBitMap.Save(Response.OutputStream, ImageFormat.Gif)
       'Start This code line save output as an image in specified Location
   
       Dim strFilePath, strUser As String
       Dim strPath As String
       strUser = Session("login")
       'strPath = "http://" & _
       '  Request.ServerVariables("server_name") & _
       '  Request.ServerVariables("script_name")
       'strPath = Strings.Replace(strPath, _
       '   "TestIntVsOffer.aspx", "Graphs/") & strUser & ".gif"
       Try
           strFilePath = Server.MapPath(".") & "/Graphs/" & strUser & ".gif"
           objBitMap.Save(strFilePath, ImageFormat.Gif)
       Catch ex As Exception
           Response.Write("error:" & ex.Message.ToString)
       End Try
   
       'End This code line save output as an image in specified Location
       objBitMap.Dispose()
   End Sub
   #End Region
   
   #Region " Function TO Display Different Colours "
   'This function returns a color for the bar and pie charts.
   Private Function GetColor(ByVal itemIndex As Integer) As Color
       Dim objColor As Color
       Select Case itemIndex
           Case 0
               objColor = Color.FromArgb(0, 0, 255)
           Case 1
               objColor = Color.FromArgb(32, 111, 11)
           Case 2
               objColor = Color.FromArgb(255, 255, 0)
           Case 3
               objColor = Color.FromArgb(24, 145, 208)
           Case 4
               objColor = Color.FromArgb(255, 153, 0)
           Case 5
               objColor = Color.FromArgb(246, 79, 23)
           Case 6
               objColor = Color.FromArgb(192, 130, 250)
           Case 7
               objColor = Color.FromArgb(102, 0, 0)
           Case 8
               objColor = Color.FromArgb(255, 204, 153)
           Case 9
               objColor = Color.FromArgb(255, 0, 255)
           Case 10
               objColor = Color.FromArgb(179, 179, 179)
           Case Else
               objColor = Color.Red
       End Select
       Return objColor
   End Function
   #End Region
   End Class

3. 创建另一个 ASPX 页面，例如 (testintvsoffer.aspx)
   在此页面上，拖放一个数据网格和一个按钮

   按钮的名称是 btnTransferToXls

   Region "On Click Button Transfer To Xls "
   
   Private Sub btnTransferToXls_Click(ByVal sender As _
           System.Object, ByVal e As System.EventArgs) _
           Handles btnTransferToXls.Click
       Try
           Dim strDateFrom, strDateTo As String
           strDateFrom = txtDateFrom.Text
           strDateTo = txtDateTo.Text
           Dim dtStart As Date
           Dim dtEnd As Date
           If Trim(strDateFrom) <> "" Then
               dtStart = ISDateValid(strDateFrom)
               If IsNothing(dtStart) Then
                   lblMessage.Text = "From Date is not valid"
                   Exit Sub
               End If
               strDateFrom = Format(dtStart, "dd-MMM-yyyy")
           Else
               strDateFrom = Format(DateTime.Now, "dd-MMM-yyyy")
               txtDateFrom.Text = Format(DateTime.Now, "dd/MM/yyyy")
           End If
           If Trim(strDateTo) <> "" Then
               dtEnd = ISDateValid(strDateTo)
               If IsNothing(dtEnd) Then
                   lblMessage.Text = "To Date is not valid"
                   Exit Sub
               End If
               strDateTo = Format(dtEnd, "dd-MMM-yyyy")
           Else
               strDateTo = Format(DateTime.Now.Date, "dd-MMM-yyyy")
               txtDateTo.Text = Format(DateTime.Now.Date, "dd/MM/yyyy")
           End If
   
           If dtStart > dtEnd Then
               lblMessage.Text = "From date should not be greater than To Date"
               Exit Sub
           End If
           If dtEnd > Format(DateTime.Now.Date, "dd-MMM-yyyy") Then
               lblMessage.Text = "To date should not be greater than _
                                   system date"
               Exit Sub
           End If
           ViewDetails()
           Session("Dtbl") = dtblIntVoffer
       Catch ex As Exception
           lblMessage.Text = ex.Message
       End Try
   
       Dim TblRcount As Int64
       'Dim dg As New DataGrid
       Dim dtblExport As New DataTable
       If Not IsNothing(Session("Dtbl")) Then
           dtblExport = CType(Session("Dtbl"), DataTable)
           TblRcount = dtblExport.Rows.Count
       End If
       Try
           'dtblIntVoffer = GetData()
           If TblRcount > 0 Then
               lblMessage.Text = ""
               Dg2.Dispose()
               Dg2.DataSource = dtblExport
               Dg2.DataBind()
               Dg2.HeaderStyle.BackColor = Color.LightGray
               Dg2.HeaderStyle.Font.Bold = True
               Dg2.ShowFooter = True
               Dg2.ItemStyle.BackColor = Color.White
               Dg2.AlternatingItemStyle.BackColor = Color.White
               Dg2.FooterStyle.BackColor = Color.LightGray
               Dg2.FooterStyle.ForeColor = Color.White
               Dg2.FooterStyle.Font.Bold = True
               ' Set the content type to Excel.
               Response.ContentType = "application/vnd.ms-excel"
               Response.AddHeader("content-disposition", _
                  "attachment;filename=InterviewVsOffer.xls")
               Response.Charset = ""
               ' Turn off the view state.
               Me.EnableViewState = False
               Dim tw As New System.IO.StringWriter
               Dim hw As New System.Web.UI.HtmlTextWriter(tw)
               ' Get the HTML for the control.
               Dg2.RenderControl(hw)
               ' Write the HTML back to the browser.
               Response.Clear()
               Response.Write(tw.ToString())
               'End the response.
               Response.End()
               'Server.Execute("frmcharts.aspx")
           Else
               lblMessage.Text = "No Records Found"
               Exit Sub
           End If
       Catch ex As Exception
           lblMessage.Text = "Error in Exporting to Excel"
       Finally
           Dg2.Dispose()
           Dg2.DataSource = Nothing
       End Try
   End Sub
   #End Region
   
   #Region "On Item Data Bound Of DataGrid 2 "
   
   Private Sub Dg2_ItemDataBound(ByVal sender As Object, _
           ByVal e As System.Web.UI.WebControls.DataGridItemEventArgs) _
           Handles Dg2.ItemDataBound
   
       Dim rColor, gColor, bColor As Int16
       Dim r1Color, g1Color, b1Color As Int16
       'rColor = 150
       'gColor = 150
       'bColor = 150
       rColor = 255
       gColor = 0
       bColor = 255
       r1Color = 0
       g1Color = 0
       b1Color = 0
   
       If e.Item.ItemType = ListItemType.Header Then
           Dim HedText As Int32
           For HedText = 18 To 49
               If HedText <= 33 Then
               e.Item.Cells(HedText).Text = _
                  e.Item.Cells(HedText).Text.Replace("1", "")
               Else
               e.Item.Cells(HedText).Text = _
                  e.Item.Cells(HedText).Text.Replace("2", "")
               End If
           Next
   
           e.Item.Cells(1).Text = _
              e.Item.Cells(1).Text.Replace("1", "")
           Dim dgItem As DataGridItem
           Dim dgCell As TableCell
           dgItem = New DataGridItem(0, 0, ListItemType.Footer)
           dgCell = New TableCell
           dgCell.ColumnSpan = 2
           dgItem.Cells.Add(dgCell)
           dgCell.Text = "Months"
           dgCell.BackColor = _
              System.Drawing.ColorTranslator.FromOle(RGB(rColor, _
              gColor, bColor))
           dgCell.ForeColor = _
             System.Drawing.ColorTranslator.FromOle(RGB(r1Color, _
             g1Color, b1Color))
           dgCell.HorizontalAlign = HorizontalAlign.Center
           'Dg1.Controls(0).Controls.AddAt(0, dgItem)
           'dgItem = New DataGridItem(0, 0, ListItemType.Footer)
           dgCell = New TableCell
           dgCell.ColumnSpan = 16
           dgItem.Cells.Add(dgCell)
           dgCell.Text = "Interview"
           dgCell.BackColor = _
             System.Drawing.ColorTranslator.FromOle(RGB(rColor, _
             gColor, bColor))
           dgCell.ForeColor = _
             System.Drawing.ColorTranslator.FromOle(RGB(r1Color, _
             g1Color, b1Color))
           dgCell.HorizontalAlign = HorizontalAlign.Center
           dgCell = New TableCell
           dgCell.ColumnSpan = 16
           dgItem.Cells.Add(dgCell)
           dgCell.Text = "Offers"
           dgCell.BackColor = _
             System.Drawing.ColorTranslator.FromOle(RGB(rColor, _
             gColor, bColor))
           dgCell.ForeColor = _
             System.Drawing.ColorTranslator.FromOle(RGB(r1Color, _
             g1Color, b1Color))
           dgCell.HorizontalAlign = HorizontalAlign.Center
           dgCell = New TableCell
           dgCell.ColumnSpan = 16
           dgItem.Cells.Add(dgCell)
           dgCell.Text = "Joinees"
           dgCell.BackColor = _
             System.Drawing.ColorTranslator.FromOle(RGB(rColor, _
             gColor, bColor))
           dgCell.ForeColor = _
             System.Drawing.ColorTranslator.FromOle(RGB(r1Color, _
             g1Color, b1Color))
           dgCell.HorizontalAlign = HorizontalAlign.Center
           Dg2.Controls(0).Controls.AddAt(0, dgItem)
       End If
   
       Dim intColCounter, ColTotal, CfinalTotal As Integer
       Dim intRowCounter As Integer
       Dim Itotal, Ototal, Jtotal As Integer
       Dim i As Int64
       Dim PerTotal As Double
       i = 1
       Dim cnt As Integer = Dg2.Items.Count + 3
   
       If e.Item.ItemType = ListItemType.Footer Then
           Dim dgItem As DataGridItem
           Dim dgCell As TableCell
           Dim dgItem1 As DataGridItem
           Dim dgItem2 As DataGridItem
           Dim dgItem3 As DataGridItem
           Dim dgCell1 As TableCell
           Dim dgCell2 As TableCell
           Dim dgCell3 As TableCell
           dgItem = New DataGridItem(cnt, cnt, ListItemType.Footer)
           dgItem1 = New DataGridItem(cnt, cnt, ListItemType.Footer)
           dgItem2 = New DataGridItem(cnt, cnt, ListItemType.Footer)
           dgItem3 = New DataGridItem(cnt, cnt, ListItemType.Footer)
           dgCell = New TableCell
           dgCell.ColumnSpan = 2
           dgItem.Cells.Add(dgCell)
           dgCell.Text = "Total"
           dgCell1 = New TableCell
           dgCell1.ColumnSpan = 2
           dgItem1.Cells.Add(dgCell1)
           dgCell1.Text = "% /Total"
           dgCell3 = New TableCell
           dgCell3.ColumnSpan = 2
           dgItem3.Cells.Add(dgCell3)
           dgCell3.Text = "*"
           dgCell2 = New TableCell
           dgCell2.ColumnSpan = 2
           dgItem2.Cells.Add(dgCell2)
           dgCell2.Text = "Pie-Graph"
           dgCell2.ForeColor = Color.Red
           dgCell2.Font.Bold = True
           Dim Intviewtoatal As Double
           Dim Offertoatal As Double
           Dim Joineestoatal As Double
   
           For intRowCounter = 0 To Dg2.Items.Count - 1
               Intviewtoatal = Intviewtoatal + _
                 CInt(Dg2.Items(intRowCounter).Cells(17).Text)
               Offertoatal = Offertoatal + _
                 CInt(Dg2.Items(intRowCounter).Cells(33).Text)
               Joineestoatal = Joineestoatal + _
                 CInt(Dg2.Items(intRowCounter).Cells(49).Text)
           Next
           For intColCounter = 2 To 49
               CfinalTotal = 0
               For intRowCounter = 0 To Dg2.Items.Count - 1
                   ColTotal = _
                     CInt(Dg2.Items(intRowCounter).Cells(intColCounter).Text)
                   CfinalTotal = _
                     CfinalTotal + ColTotal
               Next
               If (intColCounter <= 17 And Intviewtoatal > 0) Then
                   ' PerTotal = CInt((CfinalTotal / Intviewtoatal) * 100)
                   PerTotal = Convert.ToDouble((CfinalTotal / _
                              Intviewtoatal) * 100)
                   PerTotal = (PerTotal.ToString("N", nfi))
                   ElseIf (intColCounter <= 33 And Offertoatal > 0) Then
                   ' PerTotal = CInt((CfinalTotal / Offertoatal) * 100)
                   PerTotal = Convert.ToDouble((CfinalTotal / _
                              Offertoatal) * 100)
                   PerTotal = (PerTotal.ToString("N", nfi))
                  Else
                   PerTotal = 0
               End If
               dgCell = New TableCell
               dgcell.Text = CfinalTotal
               dgItem.Cells.Add(dgCell)
               Dg2.Controls(0).Controls.AddAt(cnt, dgItem)
               dgCell1 = New TableCell
               dgCell1.Text = PerTotal
               dgItem1.Cells.Add(dgCell1)
               Dg2.Controls(0).Controls.AddAt(cnt + 1, dgItem1)
           Next
   
           dgCell3 = New TableCell
           'dgCell3.Text = PerTotal
           dgCell3.ColumnSpan = 10
           dgItem3.Cells.Add(dgCell3)
           Dg2.Controls(0).Controls.AddAt(cnt + 2, dgItem3)
           'This code for getting the Graph from another page
           'and integrate with datagrid that together exports to Excel
           'New Code Add for Maintain Global Tem Table
           'for same session or conn for one user
           'clsCon.OpenCon(ConfigurationSettings.
           '      AppSettings("strConnection").ToString)
           'SQLSTR = "select RefType,total from CanEnter "
           Dim sqlstr As String
           Dim oleAdap As OleDbDataAdapter
           Dim ds1 As DataSet
           Dim Int As Int64
           sqlstr = "select ROWNUM Rowcnt,RefType,total," & _
                    "totalper from CANINTERVOFFER order by ROWNO "
           oleAdap = New OleDbDataAdapter(sqlstr, clsCon.Con)
           ds1 = New DataSet
           oleAdap.Fill(ds1)
           Session("ds1") = ds1
           clsCon.closeCon()
           'End New Code Add for Maintain Global Tem
           'Table for same session or conn for one user
           Dim Img As New System.Web.UI.WebControls.Image
           ' This code of line Execute the page
           ' on server side get the output this page
           Server.Execute("frmCharts.aspx")
           Dim strFilePath As String
           'strFilePath = Server.MapPath(".") & "/Images/Graph.gif"
           'Response.Write(Server.MapPath("."))
            Dim strPath, struser As String
           strPath = "http://" & Request.ServerVariables("server_name") _
                     & Request.ServerVariables("script_name").ToLower().Trim
           struser = Session("login")
           strPath = Strings.Replace(strPath, _
                     ("testintvsoffer.aspx"), "Graphs/") & _
                     struser & ".gif"
           Img.ImageUrl = strPath
           ' Img.ImageUrl = "d:/deep/test1.gif"
           dgCell2 = New TableCell
           dgCell2.Controls.Add(Img)
           dgItem2.Cells.Add(dgCell2)
           Dg2.Controls(0).Controls.AddAt(cnt + 3, dgItem2)
           'End This code for Get the Graph from another page and
           'integrate with datagrid that together export to Excel
           'Dim lc As LiteralControl
           'lc.Text = "Deepchand"
           'Dg2.Controls.Add(lc)
           'Dg2.Controls(0).Controls.AddAt(cnt + 2, dgItem1)
           i = i + 1
       End If
   End Sub
   #End Region

优点

1. 多个用户可以同时访问
2. 根据用户会话生成图像（图表）
3. 从报表的角度，将 GIF 图像与数据一起导出到 Excel 文件中
4. 为每个用户请求生成动态图表
5. 数据的图形表示，以便用户更容易理解系统数据的输出

Possible Enhancements

CreatePieChart 函数缺乏第三方图形组件可能提供的冲击力和活力，但此函数在不到 15 分钟内创建，不花费任何费用（除了我的时间），而且最重要的是，源代码随时可用，供您感兴趣的任何未来更改或增强。

CreatePieChart 函数的一个可能的增强是添加传递 SQL 字符串而不是数据库表名的能力。 在目前的状态下，CreatePieChart 图表只能为具有非常简单的数据模型的数据库创建饼图。 如果能够指定 SQL 字符串，则可以创建数据来自多个表的图表，或者通过指定 WHERE 子句来绘制数据库表中某些行的图表。

结论

由于 ASP.NET 允许您使用 .NET Framework 中的类，因此只需少量代码，您就可以从 Web 页面创建自己的动态图像。 这些图像可以保存到 Web 服务器的文件系统中，也可以直接流式传输到浏览器。 您需要的任何图像生成例程都包含在 .NET Framework 中。 您可以创建的图表和图形仅受您的想象力限制。