用VB.Net编写通用报表组件（2） - VB教程 - 新闻中心 - PHP168整站系统 powered by www.php168.com

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3、定义公共类CReport，该类为供应用软件调用。定义类CReport的私有变量frmSetup，该变量将启动一个供用户操作的界面。定义类CReport的属性DataGrid，该属性供用户传送一待打印的数据网格名，定义类CReport的属性DataTable，该属性供用户传送一待打印的数据表格名。定义类CReport的公有方法Run，该方法启动该组件。分别编写它们的功能。代码如下：

    Public Class CReport
        Dim frmSetup As New frmPrintSetup()

        Public Property DataGrid() As DataGrid
            Get
                ' DataTable = mDataTable
            End Get
            Set(ByVal Value As DataGrid)
                frmSetup.DataTable = Value.DataSource
                frmSetup.MainTitle = Value.CaptionText
            End Set
        End Property

        Public Property DataTable() As DataTable
            Get
                ' DataTable = mDataTable
            End Get
            Set(ByVal Value As DataTable)
                frmSetup.DataTable = Value
            End Set
        End Property

        Public Sub Run()
            frmSetup.ShowDialog()
            frmSetup = Nothing
        End Sub
End Class

4、定义公共类CPublicExcel，该类主要定义Excel的程序对象，启动Excel并打印及保存报表。代码如下：

    '这个类是不改变的 (公共性)
    Public Class CPublicExcel
        Public xlApp As New Excel.Application() 'excel程序对象
        'Public gblnSaveReport As Boolean    '  该Report是否输出成为XLS文件
        'Public gstrPath As String           '  该Report输出成为XLS的文件名

        Private ExcelWasNotRunning As Boolean '原来的excel程序的状态
        Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal
	lpClassName As String, ByVal lpWindowName As String) As Long
        Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal
	hWnd As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As Long) 
As Long

 '识别excel是否运行
        Private Function DetectExcel() As Boolean
            Const WM_USER = 1024
            Dim hWnd As Long
            hWnd = FindWindow("XLMAIN", 0)
            If hWnd <> 0 Then   ' hWnd <> 0 means Excel is 
running.
                SendMessage(hWnd, WM_USER + 18, 0, 0)
                DetectExcel = True
            Else
                DetectExcel = False
            End If
        End Function

      '打开excel
        Public Sub OpenExcelSheet()
            ExcelWasNotRunning = Not DetectExcel()
            If ExcelWasNotRunning Then
                xlApp = GetObject("", "Excel.Application")
            Else
                xlApp = GetObject(, "Excel.Application")
            End If
            xlApp.Workbooks.Add()  '(ExcelSheetName)
        End Sub
'打印预览报表
        Public Sub PrintPreview()
            xlApp.Caption = "报表"
            xlApp.DisplayAlerts = False
            xlApp.Visible = True
            xlApp.ActiveWorkbook.PrintPreview()
            xlApp.Visible = False
        End Sub
'打印报表
        Public Sub Print()
            xlApp.DisplayAlerts = False
            xlApp.Visible = False
            xlApp.ActiveWorkbook.PrintOut()
        End Sub
'保存报表
        Public Sub SaveAs(ByVal FileName As String)
            Dim file As System.IO.File
            Try
                'If file.Exists(FileName) = True Then
                ' file.Delete(FileName)
                'End If
                xlApp.ActiveWorkbook.SaveAs(FileName)
            Catch ex As Exception 'When y = 0   ' Catch the error.

                MsgBox(ex.ToString)   ' Show friendly error message.
                '    Beep()   ' Beep after error processing.
            End Try
        End Sub
    End Class

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