第二步:创建表示层
具体步骤如下:
1.新建一个Windows应用程序,命名为:“Windows Form For 表示层”。
2.在窗体上添加一个DataGrid,一个Button,Button1的text为“Load”,作用是:从业务层读取数据。
3.在解决方案窗体中添加Web 引用,将我们自己建立的Web Service for 业务层引入到当前项目中。
4.向Button1的Click事件添加如下代码:
Dim Customer_Ds As New localhost.super_ds()
Dim ser1 As New localhost.Service1()
Customer_Ds.Merge(ser1.Get_Dataset)
DataGrid1.DataSource = Customer_Ds
这里我们调用了Web Service的Get_DataSet函数,Update_DataSet方法的调用与此完全相同。
表示层的完整代码如下:
Imports Data_Access_表示层
Public Class Form1
Inherits System.Windows.Forms.Form
#Region " Windows Form Designer generated code "
Public Sub New()
MyBase.New()
'This call is required by the Windows Form Designer.
InitializeComponent()
'Add any initialization after the InitializeComponent() call
End Sub
'Form overrides dispose to clean up the component list.
Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
If disposing Then
If Not (components Is Nothing) Then
components.Dispose()
End If
End If
MyBase.Dispose(disposing)
End Sub
Friend WithEvents Button1 As System.Windows.Forms.Button
Friend WithEvents Button2 As System.Windows.Forms.Button
Friend WithEvents Button3 As System.Windows.Forms.Button
Friend WithEvents Client_DataSet As Data_Access_表示层.localhost.super_ds
Friend WithEvents DataGrid1 As System.Windows.Forms.DataGrid
'Required by the Windows Form Designer
Private components As System.ComponentModel.Container
'NOTE: The following procedure is required by the Windows Form Designer
'It can be modified using the Windows Form Designer.
'Do not modify it using the code editor.
<System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
Me.Button1 = New System.Windows.Forms.Button()
Me.Button2 = New System.Windows.Forms.Button()
Me.Button3 = New System.Windows.Forms.Button()
Me.Client_DataSet = New Data_Access_表示层.localhost.super_ds()
Me.DataGrid1 = New System.Windows.Forms.DataGrid()
CType(Me.Client_DataSet, System.ComponentModel.ISupportInitialize).BeginInit()
CType(Me.DataGrid1, System.ComponentModel.ISupportInitialize).BeginInit()
Me.SuspendLayout()
'
'Button1
'
Me.Button1.Location = New System.Drawing.Point(88, 360)
Me.Button1.Name = "Button1"
Me.Button1.TabIndex = 0
Me.Button1.Text = "load"
'
'Button2
'
Me.Button2.Location = New System.Drawing.Point(232, 360)
Me.Button2.Name = "Button2"
Me.Button2.TabIndex = 1
Me.Button2.Text = "update"
'
'Button3
'
Me.Button3.Location = New System.Drawing.Point(376, 360)
Me.Button3.Name = "Button3"
Me.Button3.TabIndex = 2
Me.Button3.Text = "clear"
'
'Client_DataSet
'
Me.Client_DataSet.DataSetName = "Client_DataSet"
Me.Client_DataSet.Locale = New System.Globalization.CultureInfo("zh-CN")
Me.Client_DataSet.Namespace = "http://www.tempuri.org/CustomerDs.xsd"
'
'DataGrid1
'
Me.DataGrid1.DataMember = ""
Me.DataGrid1.Location = New System.Drawing.Point(40, 56)
Me.DataGrid1.Name = "DataGrid1"
Me.DataGrid1.Size = New System.Drawing.Size(480, 264)
Me.DataGrid1.TabIndex = 3
'
'Form1
'
Me.AutoScaleBaseSize = New System.Drawing.Size(6, 14)
Me.ClientSize = New System.Drawing.Size(568, 429)
Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.DataGrid1, Me.Button3, Me.Button2, Me.Button1})
Me.Name = "Form1"
Me.Text = "Form1"
CType(Me.Client_DataSet, System.ComponentModel.ISupportInitialize).EndInit()
CType(Me.DataGrid1, System.ComponentModel.ISupportInitialize).EndInit()
Me.ResumeLayout(False)
End Sub
#End Region
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim Customer_Ds As New localhost.super_ds()
Dim ser1 As New localhost.Service1()
Customer_Ds.Merge(ser1.Get_Dataset)
DataGrid1.DataSource = Customer_Ds
End Sub
End Class
总结:可见,表示层窗体上完全没有数据库连接控件,它与数据库的连接任务是通过业务层来完成的,这样,程序的结构更加清晰,当然业务层的实现也可以用其他方法,比如:写一个自己的类来完成与数据库的数据传输
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