在 2010 年 vb.net 显示报告中太慢，使用 crytal 报告

Question

我正在使用此代码来显示报告

Dim rpt As New CrystalReport1()
Dim sql As String
Dim where As String


If con Is Nothing OrElse con.State = ConnectionState.Closed Then
    'MsgBox("closed")
    OpenCon()
End If
Dim m As String
m = ""
For Each n As TreeNode In GetCheck(TreeView1.Nodes)
    If n.Tag = 1 Then
        m = m
    Else
        If m = "" Then
            m = (n.Tag)
        Else
            m = m & ", " & (n.Tag)
        End If
    End If
Next
sql = "SELECT [bran_id],[f01],[f02],[f03],[f04],[f05],[f06],[f07],[f08],[bran_name],[comp_id],[comp_name],'" & dtStart.Value.Date & "' AS start_date, '" & dtEnd.Value.Date & "' AS end_date FROM [v_complain]"
If m = "" Then
    MsgBox("لم يتم تحديد اى مدينة من فضلك قم بالاختيار اولا")
    Exit Sub
Else
    where = " WHERE bran_id in (" & m & ") and f02 between CONVERT(date,'" & dtStart.Value.Date & "',103) and CONVERT(date,'" & dtEnd.Value.Date & "',103)"
    sql = sql + where
    If cbF06.Checked = True Then
        where = " AND (f06 like N'') or (f06 is null)"
        sql = sql + where
    End If
    If cbF07.Checked = True Then
        where = " AND (f07 like N'') or (f07 is null)"
        sql = sql + where
    End If

    Dim dscmd As New SqlDataAdapter(sql, con)
    Dim ds As New DataTable
    dscmd.Fill(ds)
    rpt.SetDataSource(ds)
    CrystalReportViewer1.ReportSource = rpt
    CrystalReportViewer1.Refresh()
End If
con.Close()

但是第一次显示报告太慢了。当我尝试在不关闭窗口的情况下再次运行它时，它可以完美地工作。有没有办法让它更快？

谢谢

Answer 1

它有多慢？几秒钟？我相信它恰好需要初始化下属报告"引擎"。我有类似的问题，我能想到的最好的办法就是显示"正在创建报告，请稍候..."向用户发送消息，以便他们。或者，当您启动应用时，您可以进行"假"调用以在后台创建虚拟报表，而不向用户显示任何内容，以便在用户准备好创建真实报表时初始化所有必需的资源。