机房重构组合查询

      进行了机房重构组合查询，涉及到一个模板设计模式。很简单的理解，就像先制作好一个模板样式，然后再创建继承这个窗体的子窗体。

       1、为什么要用模板

        有了模板窗体之后，很大程度上方便了我们创造与之相似度很大（窗体界面相同，控件属性相同，公共的方法抽象出来放在模板窗体中）的继承子窗体（子窗体这时候可以有自己私有的属性和方法）。减少了重复的代码量，和相同方法的声明定义（只需重写即可），在继承子窗体中可以更清楚的明白个体继承子窗体之间的区别在那。

        2、如何创建模板并使用模板

       他们的实体界面在未运行前有一定的区别，如何创建如下操作：

       1）首先在UI层添加一个普通的窗体，把窗体的界面设置好，对控件的属性和抽象方法写在代码层。

        

Imports System.DataImports System.IOImports EntityPublic Class frmGroupQuery    '定义一个实体，用于接收文本框或者时间空间传递的内容    Public txt1 As String = ""    Public txt2 As String = ""    Public txt3 As String = ""    Protected GroupQueryInfo As New Entity.E_GroupQueryEntity    '窗体加载    Private Sub frmGroupQuery_Load(sender As Object, e As EventArgs) Handles MyBase.Load        cmbOperator1.Items.Add(">")        cmbOperator1.Items.Add("<")        cmbOperator1.Items.Add("=")        cmbOperator1.Items.Add("<>")        cmbOperator2.Items.Add(">")        cmbOperator2.Items.Add("<")        cmbOperator2.Items.Add("=")        cmbOperator2.Items.Add("<>")        cmbOperator3.Items.Add(">")        cmbOperator3.Items.Add("<")        cmbOperator3.Items.Add("=")        cmbOperator3.Items.Add("<>")        '关系            cmbRelations1.Items.Add("与")        cmbRelations1.Items.Add("或")        cmbRelations1.Items.Add("")        cmbRelations2.Items.Add("与")        cmbRelations2.Items.Add("或")        cmbRelations2.Items.Add("")        'DateTimePicker控件的可见性          dtp1.Visible = False        dtp2.Visible = False        dtp3.Visible = False        '在加载的时候，只有第一行控件可用，后两行控件不可用            cmbField2.Enabled = False        cmbField3.Enabled = False        cmbOperator2.Enabled = False        cmbOperator3.Enabled = False        cmbRelations2.Enabled = False        txtContent2.Enabled = False        txtContent3.Enabled = False        '当选中dgvGroupCheck控件就选中行            dgvGroupCheck.SelectionMode = DataGridViewSelectionMode.FullRowSelect        Dim i As Integer        For i = 0 To dgvGroupCheck.Columns.Count - 1            dgvGroupCheck.Columns(i).Width = DataGridViewAutoSizeColumnMode.AllCells        Next    End Sub    '清除功能    Private Sub btnClear_Click(sender As Object, e As EventArgs) Handles btnClear.Click        cmbField1.Text = ""        cmbField2.Text = ""        cmbField3.Text = ""        cmbOperator1.Text = ""        cmbOperator2.Text = ""        cmbOperator3.Text = ""        txtContent1.Text = ""        txtContent2.Text = ""        txtContent3.Text = ""        cmbRelations1.Text = ""        cmbRelations2.Text = ""        dgvGroupCheck.DataSource = ""    End Sub    Private Sub btnQuery_Click(sender As Object, e As EventArgs) Handles btnQuery.Click        dgvGroupCheck.DataSource = ""        '判断组合框不为空            If cmbRelations1.Text = "" Then '如果第一个组合关系框为空                If cmbField1.Text = "" Or cmbOperator1.Text = "" Or txt1 = "" Then                MsgBox("第一行查询条件不能为空！", , "提示")                Exit Sub            End If        End If        If cmbRelations1.Text <> "" Then '如果选择了第一个组合关系                If cmbField2.Text = "" Or cmbOperator2.Text = "" Or txt2 = "" Then                MsgBox("第二行查询条件不能为空！", , "提示")                Exit Sub            End If        Else            If cmbRelations2.Text <> "" Then '选择了第二个组合关系                    If cmbField1.Text = "" Or cmbOperator1.Text = "" Or txt1 = "" Or                    cmbField2.Text = "" Or cmbField2.Text = "" Or txt2 = "" Or                    cmbField3.Text = "" Or cmbField3.Text = "" Or txt3 = "" Then                    MsgBox("第三行查询条件不能为空", , "提示")                    Exit Sub                End If            End If        End If        '给实体赋值            GroupQueryInfo.tableName = GetTable()        GroupQueryInfo.cmbField1 = GetDBName(cmbField1.Text.Trim())        GroupQueryInfo.cmbField2 = GetDBName(cmbField2.Text.Trim())        GroupQueryInfo.cmbField3 = GetDBName(cmbField3.Text.Trim())        GroupQueryInfo.cmbOperator1 = cmbOperator1.Text.Trim()        GroupQueryInfo.cmbOperator2 = cmbOperator2.Text.Trim()        GroupQueryInfo.cmbOperator3 = cmbOperator3.Text.Trim()        GroupQueryInfo.txtContent1 = txt1        GroupQueryInfo.txtContent2 = txt2        GroupQueryInfo.txtContent3 = txt3        GroupQueryInfo.cmbRelations1 = GetDBName(cmbRelations1.Text.Trim())        GroupQueryInfo.cmbRelations2 = GetDBName(cmbRelations2.Text.Trim())        '给外观层方法传递参数            Dim table As DataTable        Dim Fgroupcheck As New Facade.Fe_GroupQueryFacade        Call Rdim()        If CheckSpecialString(arrayControl) Then            Exit Sub        End If        table = Fgroupcheck.GroupQuery(GroupQueryInfo)        If (table.Rows.Count = 0) Then            MsgBox("没有符合条件的记录，请重新设置查询条件", , "提示")            dgvGroupCheck.DataSource = Nothing        Else            Call Todatagridview()        End If    End Sub    '定义虚函数获取字段名    Public Overridable Function GetDBName(ByVal control As String) As String        Return ""    End Function    '定义虚函数获取数据库名    Protected Overridable Function GetTable() As String        Return ""    End Function    '把表显示到dgvGroupCheck中        Protected Overridable Sub Todatagridview()        dgvGroupCheck.AutoSizeColumnsMode = DataGridViewAutoSizeColumnMode.AllCells    End Sub    '当一个组合关系框的内容发生改变时，设置第二行的查询框状态    Private Sub cmbRelations1_SelectedIndexChanged(sender As Object, e As EventArgs) Handles cmbRelations1.SelectedIndexChanged        cmbField2.Enabled = True        cmbOperator2.Enabled = True        txtContent2.Enabled = True        cmbRelations2.Enabled = True    End Sub    '当第二个组合关系框的内容发生改变时,设置第三行查询框的状态（是否可用）      Private Sub cmbRelations2_SelectedIndexChanged(sender As Object, e As EventArgs) Handles cmbRelations2.SelectedIndexChanged        cmbField3.Enabled = True        cmbOperator3.Enabled = True        txtContent3.Enabled = True    End Sub    '针对查询与日期、时间有关的问题      Private Sub cmbField1_SelectedIndexChanged(sender As Object, e As EventArgs) Handles cmbField1.SelectedIndexChanged        If cmbField1.Text = "上机日期" Or cmbField1.Text = "下机日期" Or cmbField1.Text = "上机时间" Or cmbField1.Text = "下机时间" Then            dtp1.Format = DateTimePickerFormat.Custom            dtp1.Visible = True            txtContent1.Visible = False            If (cmbField1.Text = "上机日期" Or cmbField1.Text = "下机日期") = True Then                txt1 = Format(dtp1.Value, "yyyy-MM-dd")            Else                dtp1.Format = DateTimePickerFormat.Time                txt1 = Format(dtp1.Value, "hh:mm:ss")            End If        Else            dtp1.Visible = False            txtContent1.Visible = True            txt1 = txtContent1.Text        End If     End Sub    '针对查询与日期、时间有关的问题      Private Sub cmbField2_SelectedIndexChanged(sender As Object, e As EventArgs) Handles cmbField2.SelectedIndexChanged        If cmbField2.Text = "上机日期" Or cmbField2.Text = "下机日期" Or cmbField2.Text = "上机时间" Or cmbField2.Text = "下机时间" Then            dtp2.Format = DateTimePickerFormat.Custom            dtp2.Visible = True            txtContent2.Visible = False            If cmbField2.Text = "上机日期" Or cmbField2.Text = "下机日期" Then                txt2 = Format(dtp2.Value, "yyyy-MM-dd")            Else                dtp2.Format = DateTimePickerFormat.Time                txt2 = Format(dtp2.Value, "hh:mm:ss")            End If        Else            dtp2.Visible = False            txtContent2.Visible = True            txt2 = txtContent2.Text        End If    End Sub    '针对查询与日期、时间有关的问题      Private Sub cmbField3_SelectedIndexChanged(sender As Object, e As EventArgs) Handles cmbField3.SelectedIndexChanged        If cmbField3.Text = "上机日期" Or cmbField3.Text = "下机日期" Or cmbField3.Text = "上机时间" Or cmbField3.Text = "下机时间" Then            dtp3.Format = DateTimePickerFormat.Custom            dtp3.Visible = True            txtContent3.Visible = False            Exit Sub            If cmbField3.Text = "上机日期" Or cmbField3.Text = "下机日期" Then                txt3 = Format(dtp3.Value, "yyyy-MM-dd")                Exit Sub            ElseIf cmbField3.Text = "上机时间" Or cmbField3.Text = "下机时间" Then                dtp3.Format = DateTimePickerFormat.Time                txt3 = Format(dtp3.Value, "hh:mm:ss")                Exit Sub            End If        Else            dtp3.Visible = False            txtContent3.Visible = True            txt3 = txtContent3.Text        End If    End Sub    Private Sub txtContent1_TextChanged(sender As Object, e As EventArgs) Handles txtContent1.TextChanged        txt1 = txtContent1.Text    End Sub    Private Sub txtContent2_TextChanged(sender As Object, e As EventArgs) Handles txtContent2.TextChanged        txt2 = txtContent2.Text    End Sub    Private Sub txtContent3_TextChanged(sender As Object, e As EventArgs) Handles txtContent3.TextChanged        txt3 = txtContent3.Text    End Sub    Private Sub btnToExcel_Click(sender As Object, e As EventArgs) Handles btnToExcel.Click        Call ImportToExcel.ImportToExcel(dgvGroupCheck)    End Sub

          2）创建继承的窗体

           

          继承的窗体与创建的模板在于继承的窗体上所有控件为锁着状态，即不可以更改属性。
          继承的窗体在代码层面可以定义自己私有的方法和变量。

          

Public Class frmWorkQuery    '单例模式      Private Shared frmWorkQuery As New frmWorkQuery    Private Sub New()        ' 此调用是设计器所必需的。        InitializeComponent()        ' 在 InitializeComponent() 调用之后添加任何初始化。    End Sub    '单例模式当主窗体点击按钮时获取该窗体的方法    Public Shared Function Getinstance() As frmWorkQuery        If frmWorkQuery Is Nothing OrElse frmWorkQuery.IsDisposed Then            frmWorkQuery = New frmWorkQuery        End If        Return frmWorkQuery    End Function    Public Overrides Function GetDBName(control As String) As String        Select Case (control)            Case "教师"                Return "UserID"            Case "级别"                Return "Level"            Case "上机日期"                Return "LoginDate"            Case "上机时间"                Return "LoginTime"            Case "下机日期"                Return "LogoutDate"            Case "下机时间"                Return "LogoutTime"            Case "机器名"                Return "Computer"            Case "状态"                Return "Online"            Case "与"                Return "and"            Case "或"                Return "or"            Case Else                Return ""        End Select    End Function    Protected Overrides Function GetTable() As String        GroupQueryInfo.tableName = "WorkLog_Info"        Return GroupQueryInfo.tableName    End Function    Private Sub frmWorkRecord_Load(sender As Object, e As EventArgs) Handles MyBase.Load        cmbField1.Items.Add("教师")        cmbField1.Items.Add("上机日期")        cmbField1.Items.Add("上机时间")        cmbField1.Items.Add("下机日期")        cmbField1.Items.Add("下机时间")        cmbField1.Items.Add("机器名")        cmbField2.Items.Add("教师")        cmbField2.Items.Add("上机日期")        cmbField2.Items.Add("上机时间")        cmbField2.Items.Add("下机日期")        cmbField2.Items.Add("下机时间")        cmbField2.Items.Add("机器名")        cmbField3.Items.Add("教师")        cmbField3.Items.Add("上机日期")        cmbField3.Items.Add("上机时间")        cmbField3.Items.Add("下机日期")        cmbField3.Items.Add("下机时间")        cmbField3.Items.Add("机器名")    End Sub    Protected Overrides Sub Todatagridview()        Dim table As New DataTable        Dim frmGroupQuery As New frmGroupQuery        Dim FacadeGroupQuery As New Facade.Fe_GroupQueryFacade        Try            table = FacadeGroupQuery.GroupQuery(GroupQueryInfo)            If table.Rows.Count = 0 Then                table.Clear()                dgvGroupCheck.DataSource = Nothing                dgvGroupCheck.Refresh()                MessageBox.Show("记录为空")            Else                dgvGroupCheck.DataSource = table                dgvGroupCheck.Columns(0).HeaderText = "用户名"                dgvGroupCheck.Columns(1).HeaderText = "级别"                dgvGroupCheck.Columns(2).HeaderText = "上机日期"                dgvGroupCheck.Columns(3).HeaderText = "上机时间"                dgvGroupCheck.Columns(4).HeaderText = "下机日期"                dgvGroupCheck.Columns(5).HeaderText = "下机时间"                dgvGroupCheck.Columns(6).HeaderText = "机器名"                dgvGroupCheck.Columns(7).HeaderText = "状态"            End If        Catch ex As Exception            MsgBox(ex.Message, vbOKOnly, "提示")        End Try    End SubEnd Class