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4、 声明类级的变量。找到设计期产生的代码部分，把下面的语句加到变量声明后面。什么？不知道变量声明在哪儿?不会吧！
Private fs As FileStream
Private ds As DataSet
Private conn As New SqlConnection("server=localhost;database=northwind;integrated security=true;")
Private currentpos As Integer = 9
5、 开始写代码了。首先是form_load
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
btnOpen.Enabled = True
btnSave.Enabled = True
btnBack.Enabled = False
btnForward.Enabled = False
End Sub
6、 open按钮的点击事件代码：
Private Sub openbtn_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnOpen.Click
Dim Opendlg As New OpenFileDialog
Opendlg.Title = "Select a picture file"
Opendlg.Filter = "(*.bmp)|*bmp|(*.jpg)|*.jpg"
Opendlg.ShowDialog()
lblPath.Text = Opendlg.FileName.ToString()
fs = New FileStream(Opendlg.FileName.ToString(), FileMode.Open, FileAccess.Read)
PictureBox1.Image = Image.FromFile(Opendlg.FileName.ToString())
End Sub
7、 save按钮的点击事件代码
Private Sub savebtn_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSave.Click
Dim sqlcomm As New SqlCommand
sqlcomm.CommandText = "INSERT INTO employees (lastname,firstname,photo) VALUES (@lastname,@firstname,@photo)"
sqlcomm.Connection = conn
Dim Data(fs.Length) As Byte
fs.Read(Data, 0, Int(fs.Length))
Dim prm1 As New SqlParameter("@lastname", txtLN.Text)
Dim prm2 As New SqlParameter("@firstname", txtFN.Text)
Dim prm3 As New SqlParameter("@photo", SqlDbType.VarBinary, Int(fs.Length), ParameterDirection.Input, False, 0, 0, "", DataRowVersion.Current, Data)
sqlcomm.Parameters.Add(prm1)
sqlcomm.Parameters.Add(prm2)
sqlcomm.Parameters.Add(prm3)
Try
conn.Open()
sqlcomm.ExecuteNonQuery() '执行插入语句
conn.Close()
fs.Close()
Catch ex As Exception
MsgBox(ex.Message)
End Try
End Sub
8、 选择view状态的事件代码
Private Sub CheckBox1_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles CheckBox1.CheckedChanged
If CheckBox1.Checked = True Then
btnOpen.Enabled = False
btnSave.Enabled = False
btnBack.Enabled = True
btnForward.Enabled = True
currentpos = 9
Dim sqlcomm As New SqlCommand
sqlcomm.CommandText = "SELECT employeeId, photo FROM employees ORDER BY employeeId"
sqlcomm.Connection = conn
Dim da As New SqlDataAdapter(sqlcomm)
Try
conn.Open()
ds = New DataSet
da.Fill(ds, "employees")
conn.Close()
Catch sqlEx As SqlException
MsgBox(sqlEx.Message)
End Try
Dim data() As Byte = ds.Tables("employees").Rows(9)("photo")
Dim stmphoto As New MemoryStream(data)
PictureBox1.Image = Image.FromStream(stmphoto)
Else
btnOpen.Enabled = True
btnSave.Enabled = True
btnBack.Enabled = False
btnForward.Enabled = False
End If
End Sub
9、 “>>”按钮点击事件代码
Private Sub forward_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnForward.Click
If currentpos = ds.Tables("employees").Rows.Count - 1 Then
Return
Else
currentpos += 1
Dim data() As Byte
data = ds.Tables("employees").Rows(currentpos)("photo")
Dim stmphoto As New MemoryStream(data)
PictureBox1.Image = Image.FromStream(stmphoto)
End If
End Sub
10、 “<<”按钮点击事件代码
Private Sub back_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnBack.Click
If currentpos = 9 Then
Return
Else
currentpos -= 1
End If
Dim Data() As Byte
Data = ds.Tables("employees").Rows(currentpos)("photo")
Dim stmPhoto As New MemoryStream(Data)
PictureBox1.Image = Image.FromStream(stmPhoto)
End Sub
11、 好了，可以运行看看了。
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