VB.NET项目技术总结

VB.NET是微软asp之后、ASP.NET之前的Web开发技术。

前台页面的拓展名是.aspx,后端扩展名是.vb，前台aspx页面继承自.aspx.vb，aspx页面基本上和asp.net中aspx页面一模一样，主要就是服务器控件都是一样的，Grid的Eval绑定表达式都是一样的。

后端的VB和C#语法还是有一定区别的， 写惯了C#,觉得vb语法不优雅

1. 基本语法：

Dim sort As String

Protected Sub BindLines()
        dropLines.DataSource = viewCurrentCountsBL.GetLines()
        dropLines.DataTextField = "DESCRIPTION"
        dropLines.DataValueField = "LINE_ID"
        dropLines.DataBind()
    End Sub

Protected Function GetIco(itemType As String) As String
        If itemType = "1" Then
            Return "<img src='/images/tool.png'/>"
        ElseIf itemType = "2" Then
            Return "<img src='/images/Kits.png'/>"
        Else
            Return ""
        End If
    End Function

    Protected Sub chkHideTools_CheckedChanged(sender As Object, e As EventArgs) Handles chkHideTools.CheckedChanged
        BindGird()
    End Sub

其中，跟C#中一些关键字差异的地方：Dim申明值类型、类变量，As 类型。Sub/End Sub,If/End If 相当于C#中If{},void Fun(){}

C#中a!=null, vb中a Is Nothing

C# ！布尔值变量、表达式写法位!flag、!IsValid(), vb中Not flag、 not IsValid()

2. VB.NET中的GridView Sorting

2.1.利用table.DefaultView.Sort='SortExpression sortDirection'

Protected Sub GridView1_Sorting(sender As Object, e As GridViewSortEventArgs) Handles GridView1.Sorting
        Dim table = Session("ViewCurrentCountGridData")
        Dim sortDirection As String
        Dim sort As String

        If table Is Nothing Then
            If Request.QueryString("operationIds") IsNot Nothing AndAlso Not String.IsNullOrEmpty(Request.QueryString("operationIds").ToString()) Then
                Dim operationIds As New System.Collections.ObjectModel.Collection(Of Long)
                table = viewCurrentCountsBL.GetItemsForOps(operationIds, chkHideTools.Checked)
                Session("ViewCurrentCountGridData") = table
            Else
                table = viewCurrentCountsBL.GetItems(Long.Parse(dropLines.SelectedValue), 0, chkHideTools.Checked)
                Session("ViewCurrentCountGridData") = table
            End If
        End If

        If String.IsNullOrEmpty(e.SortExpression) Then
            sort = "last_update desc"
        Else
            If ViewState("SortDirection") IsNot Nothing AndAlso ViewState("SortDirection").ToString() = "asc" Then
                sortDirection = "desc"
            Else
                sortDirection = "asc"
            End If
            sort = e.SortExpression + " " + sortDirection
            ViewState("SortDirection") = sortDirection
        End If
        table.DefaultView.Sort = sort
        GridView1.DataSource = table.DefaultView
        GridView1.DataBind()
    End Sub

2.2 用DataTable.Select(filterExpression, sortStr) ，下面的4中有示例代码。

3. Decimal取14位：

Math.Round(Decimal.Parse(hours.ToString()),14)

4. 实现下图效果：

如果是按照Hours Remaining排序的时候，根据Hours Remaining值的范围2以下，2-4，4-6，6-8，8-10，10以上，"分组"显示，显示组标题。

4.1. 后台计算得出规律，生成json字符串，在前台解析，通过JS添加tr

   Protected Sub GridView1_Sorting(sender As Object, e As GridViewSortEventArgs) Handles GridView1.Sorting
        Dim table = Session("ViewCurrentCountGridData")
        Dim sortDirection As String
        Dim sort As String
        Dim filter = String.Format("hours<={0}", hoursUnder)

        If table Is Nothing Then
            table = GetData()
            Session("ViewCurrentCountGridData") = table
        End If

        If String.IsNullOrEmpty(e.SortExpression) Then
            sort = "last_update desc"
        Else
            If ViewState("SortDirection") IsNot Nothing AndAlso ViewState("SortDirection").ToString() = "asc" Then
                sortDirection = "desc"
            Else
                sortDirection = "asc"
            End If
            sort = e.SortExpression + " " + sortDirection
            ViewState("SortField") = e.SortExpression
            ViewState("SortDirection") = sortDirection
        End If

        GridView1.DataSource = table.Select(filter, sort)
        GridView1.DataBind()

        If e.SortExpression.ToLower() = "hours" Then
            SetUnderHours(table)
        End If

    End Sub

Protected Sub SetUnderHours(table As DataTable)
        Dim listHours = (
            From item In table.AsEnumerable() Where Not item.IsNull("hours")
            Select item.Field(Of Decimal)("hours")
            ).ToList().Where(Function(m) m <= hoursUnder).ToList()

        Dim query2 = From el In listHours Group el By key = GetUnderKey(el) Into g = Group _
                     Select New With { _
        .Key = key, _
        .min = g.Min(),
        .max = g.Max()
        }

        Dim list = query2.ToList()

        If list IsNot Nothing Then
            json = "["
            For i As Integer = 0 To list.Count - 1
                If i = list.Count - 1 Then
                    json += "{'underKey':" + list(i).Key.ToString() + ",'min':" + list(i).min.ToString() + ",'max':" + list(i).max.ToString() + "}"
                Else
                    json += "{'underKey':" + list(i).Key.ToString() + ",'min':" + list(i).min.ToString() + ",'max':" + list(i).max.ToString() + "},"
                End If
            Next
            json += "]"
        End If
    End Sub

 Public Function GetUnderKey(hours As Decimal) As Integer
        If hours <= 0 Then
            Return -1
        ElseIf 0 < hours And hours <= 2 Then
            Return 2
        ElseIf 2 < hours And hours <= 4 Then
            Return 4
        ElseIf 4 < hours And hours <= 6 Then
            Return 6
        ElseIf 6 < hours And hours <= 8 Then
            Return 8
        ElseIf 8 < hours And hours <= 10 Then
            Return 10
        ElseIf hours > 10 Then
            Return 11
        Else
            Return -1
        End If
    End Function

<script type="text/javascript">
        $(function () {
            var jsonStr = eval("<%=json%>");
            var sortField = "<%=ViewState("SortField")%>";
            var sortDirection="<%=ViewState("SortDirection")%>";
            if (sortField.toLowerCase() == "hours") {
                $.each(jsonStr, function (i, item) {
                    if (sortDirection == "desc") {
                        var maxRow = $("#<%=GridView1.ClientID %> tr input[data-field='hours'][value='" + item.max.toFixed(14) + "']").eq(0).parent().parent();
                        var title = item.underKey == 11 ? "Over 10 Hours" : "Under " + item.underKey + " Hours";
                        maxRow.before($("<tr><td style='background-color:blue;color:white'>" + title + " </td><td colspan='5'></td></tr>"));
                    }
                    else {
                        var minRow = $("#<%=GridView1.ClientID %> tr input[data-field='hours'][value='" + item.min.toFixed(14) + "']").eq(0).parent().parent();
                        var title = item.underKey == 11 ? "Over 10 Hours" : "Under " + item.underKey + " Hours";
                        minRow.before($("<tr><td style='background-color:blue;color:white'>" + title + " </td><td colspan='5'></td></tr>"));
                    }
                });
            }
        });
    </script>

其中的难点：1.思路 2.vb的linq语法，特别根据列值，得出计算值再分组，不太好弄。　　

4.2 用C# linq 实现的group，返回json的代码如下：

4.3 在服务端插入group row，代码如下：