使用列表框从 SQL 获取图像到图片框 VB
Get Image from SQL using Listbox to picturebox VB
我正在尝试使用 VB 中的列表框将图像从 SQL 获取到图片框。
这是我的 sql 示例 table。
这是我的 VB 设计表单，所以我想做的是当我加载表单时，如果选择了列表框中的项目，我希望它获取图像（二进制数据）从 sql 到 vb net.
中的图片框
我正在使用它的代码给了我这个错误：
VB完整代码：
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
connect()
Dim co As New SqlConnection("Data Source=WXCQSDQSD\SQLEXPRESS;Initial Catalog=food;Integrated Security = True")
co.Open()
Dim com As New SqlCommand("SELECT Image from Items where ItemName = '" & ListBox1.SelectedIndex & "'", co)
Dim img As Byte() = DirectCast(com.ExecuteScalar(), Byte())
Dim ms As MemoryStream = New MemoryStream(img)
Dim dt = GetDataFromSql()
Dim BndSrc As New BindingSource()
BndSrc.DataSource = dt
ListBox1.DisplayMember = "ItemName"
ListBox1.DataSource = BndSrc
TextBox1.DataBindings.Add("Text", BndSrc, "ItemID")
TextBox2.DataBindings.Add("Text", BndSrc, "ItemName")
TextBox3.DataBindings.Add("Text", BndSrc, "Details")
PictureBox1.Image = Image.FromStream(ms)
End Sub
Private Function GetDataFromSql() As DataTable
Dim dt As New DataTable
Using connection As New SqlConnection("Data Source=WXCQSDQSD\SQLEXPRESS;Initial Catalog=food;Integrated Security = True"),
cmd As New SqlCommand("select * FROM Items", connection)
connection.Open()
Using reader = cmd.ExecuteReader
dt.Load(reader)
End Using
End Using
Return dt
End Function
进口System.Data.SqlClient
进口 System.IO
Public Class Form1
Dim con As SqlConnection
Dim cmd As SqlCommand
Dim rdr As SqlDataReader
Dim da As SqlDataAdapter
Private Const cs As String = "ConnectionString"
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
con = New SqlConnection(cs)
con.Open()
cmd = New SqlCommand("select * from [dbo].[Item_Details]", con)
rdr = cmd.ExecuteReader()
While rdr.Read
ListBox1.Items.Add(rdr(1))
End While
con.Close()
End Sub
Private Sub ListBox1_MouseClick(sender As Object, e As MouseEventArgs) Handles ListBox1.MouseClick
Try
con = New SqlConnection(cs)
con.Open()
da = New SqlDataAdapter("Select * from Item_Details where itemname='" & ListBox1.SelectedItem.ToString() & "'", con)
Dim dt As New DataTable
da.Fill(dt)
For Each row As DataRow In dt.Rows
TextBox1.Text = row(0).ToString()
TextBox2.Text = row(1).ToString()
TextBox3.Text = row(2).ToString()
Dim data As Byte() = row(3)
Dim ms As New MemoryStream(data)
PictureBox1.Image = Image.FromStream(ms)
Next
Catch ex As Exception
MsgBox(ex.Message)
End Try
End Sub
结束Class
从Form.Load中删除图片检索。我们在GetDataFromSql函数中选择了所有的数据。魔术发生在 ListBox1.SelectedIndexChanged 方法中。
SelectedIndexChanged 将作为 Form.Load 中代码的结果以及每次选择更改时发生。当我们将列表框绑定到绑定源时，整行添加为 DataRowView。我们可以使用它来获取 Image 列中的数据。首先检查该字段是否为空。接下来转换为字节数组。获取字节数组并将其传递给 MemoryStream 的构造函数。需要处理流，因此它位于 Using 块中。最后可以将流分配给PictureBox.
Image属性
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Dim dt = GetDataFromSql()
Dim BndSrc As New BindingSource()
BndSrc.DataSource = dt
ListBox1.DisplayMember = "ItemName"
ListBox1.DataSource = BndSrc
TextBox1.DataBindings.Add("Text", BndSrc, "ItemID")
TextBox2.DataBindings.Add("Text", BndSrc, "ItemName")
TextBox3.DataBindings.Add("Text", BndSrc, "Details")
End Sub
Private Function GetDataFromSql() As DataTable
Dim dt As New DataTable
Using connection As New SqlConnection("Data Source=WXCQSDQSD\SQLEXPRESS;Initial Catalog=food;Integrated Security = True"),
cmd As New SqlCommand("select * FROM Items", connection)
connection.Open()
Using reader = cmd.ExecuteReader
dt.Load(reader)
End Using
End Using
Return dt
End Function
Private Sub ListBox1_SelectedIndexChanged(sender As Object, e As EventArgs) Handles ListBox1.SelectedIndexChanged
Dim row = DirectCast(ListBox1.SelectedItem, DataRowView)
If row("Image") IsNot Nothing Then
Dim b() As Byte = DirectCast(row("Image"), Byte()) '< ------ Cast the field to a Byte array.
Using ms As New System.IO.MemoryStream(b)
PictureBox1.Image = System.Drawing.Image.FromStream(ms)
End Using
Else
PictureBox1.Image = Nothing
End If
End Sub
编辑
我将代码切换到可用于测试的数据库。尽管它不是您的数据库，但我相信您将能够遵循代码。
这是我的数据库的架构。
主要区别是我将 DataTable 移动到 class 级别变量，因此可以从所有方法中看到它。我将 GetDataFromSql 更改为 Sub。它将数据添加到 class 级别 DataTable (Bounddt)。 AddItem 方法首先从文件中获取 Byte()。该行被添加到 DataTable 中，带有一个 Object 数组，其中的元素与 DataTable 匹配。
Private Bounddt As New DataTable
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
GetDataFromSql()
Dim BndSrc As New BindingSource()
BndSrc.DataSource = Bounddt
ListBox1.DisplayMember = "CustomerID"
ListBox1.DataSource = BndSrc
TextBox1.DataBindings.Add("Text", BndSrc, "CustomerID")
TextBox2.DataBindings.Add("Text", BndSrc, "CustomerName")
End Sub
Private Sub GetDataFromSql()
Using connection As New SqlConnection("Data Source=****;Initial Catalog='Small Database';Integrated Security=True;Connect Timeout=30;Encrypt=False;TrustServerCertificate=False;ApplicationIntent=ReadWrite;MultiSubnetFailover=False"),
cmd As New SqlCommand("select * FROM Sales.Customer", connection)
connection.Open()
Using reader = cmd.ExecuteReader
Bounddt.Load(reader)
End Using
End Using
'Return dt
End Sub
Private Sub ListBox1_SelectedIndexChanged(sender As Object, e As EventArgs) Handles ListBox1.SelectedIndexChanged
Dim row = DirectCast(ListBox1.SelectedItem, DataRowView)
If row("Picture") IsNot Nothing Then
Dim b() As Byte = DirectCast(row("Picture"), Byte()) '< ------ Cast the field to a Byte array.
Using ms As New System.IO.MemoryStream(b)
PictureBox1.Image = System.Drawing.Image.FromStream(ms)
End Using
Else
PictureBox1.Image = Nothing
End If
End Sub
Private Sub AddItem()
Dim picture = GetByteArr("C:\Users\maryo\OneDrive\Documents\Graphics\Animals\squirrel.png")
Bounddt.Rows.Add({5, "George", 74, 62, "George", picture})
End Sub
Private Function GetByteArr(path As String) As Byte()
Dim img = Image.FromFile(path)
Dim arr As Byte()
Dim imgFor As Imaging.ImageFormat
Dim extension = path.Substring(path.LastIndexOf(".") + 1)
'There is a longer list of formats available in ImageFormat
Select Case extension
Case "png"
imgFor = Imaging.ImageFormat.Png
Case "jpg", "jpeg"
imgFor = Imaging.ImageFormat.Jpeg
Case "bmp"
imgFor = Imaging.ImageFormat.Bmp
Case Else
MessageBox.Show("Not a valid image format")
Return Nothing
End Select
Using ms As New MemoryStream
img.Save(ms, imgFor)
arr = ms.ToArray
End Using
Return arr
End Function
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
AddItem()
End Sub
我正在尝试使用 VB 中的列表框将图像从 SQL 获取到图片框。
这是我的 sql 示例 table。
这是我的 VB 设计表单，所以我想做的是当我加载表单时，如果选择了列表框中的项目，我希望它获取图像（二进制数据）从 sql 到 vb net.
中的图片框我正在使用它的代码给了我这个错误：
VB完整代码：
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
connect()
Dim co As New SqlConnection("Data Source=WXCQSDQSD\SQLEXPRESS;Initial Catalog=food;Integrated Security = True")
co.Open()
Dim com As New SqlCommand("SELECT Image from Items where ItemName = '" & ListBox1.SelectedIndex & "'", co)
Dim img As Byte() = DirectCast(com.ExecuteScalar(), Byte())
Dim ms As MemoryStream = New MemoryStream(img)
Dim dt = GetDataFromSql()
Dim BndSrc As New BindingSource()
BndSrc.DataSource = dt
ListBox1.DisplayMember = "ItemName"
ListBox1.DataSource = BndSrc
TextBox1.DataBindings.Add("Text", BndSrc, "ItemID")
TextBox2.DataBindings.Add("Text", BndSrc, "ItemName")
TextBox3.DataBindings.Add("Text", BndSrc, "Details")
PictureBox1.Image = Image.FromStream(ms)
End Sub
Private Function GetDataFromSql() As DataTable
Dim dt As New DataTable
Using connection As New SqlConnection("Data Source=WXCQSDQSD\SQLEXPRESS;Initial Catalog=food;Integrated Security = True"),
cmd As New SqlCommand("select * FROM Items", connection)
connection.Open()
Using reader = cmd.ExecuteReader
dt.Load(reader)
End Using
End Using
Return dt
End Function
进口System.Data.SqlClient 进口 System.IO Public Class Form1
Dim con As SqlConnection
Dim cmd As SqlCommand
Dim rdr As SqlDataReader
Dim da As SqlDataAdapter
Private Const cs As String = "ConnectionString"
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
con = New SqlConnection(cs)
con.Open()
cmd = New SqlCommand("select * from [dbo].[Item_Details]", con)
rdr = cmd.ExecuteReader()
While rdr.Read
ListBox1.Items.Add(rdr(1))
End While
con.Close()
End Sub
Private Sub ListBox1_MouseClick(sender As Object, e As MouseEventArgs) Handles ListBox1.MouseClick
Try
con = New SqlConnection(cs)
con.Open()
da = New SqlDataAdapter("Select * from Item_Details where itemname='" & ListBox1.SelectedItem.ToString() & "'", con)
Dim dt As New DataTable
da.Fill(dt)
For Each row As DataRow In dt.Rows
TextBox1.Text = row(0).ToString()
TextBox2.Text = row(1).ToString()
TextBox3.Text = row(2).ToString()
Dim data As Byte() = row(3)
Dim ms As New MemoryStream(data)
PictureBox1.Image = Image.FromStream(ms)
Next
Catch ex As Exception
MsgBox(ex.Message)
End Try
End Sub
结束Class
从Form.Load中删除图片检索。我们在GetDataFromSql函数中选择了所有的数据。魔术发生在 ListBox1.SelectedIndexChanged 方法中。
SelectedIndexChanged 将作为 Form.Load 中代码的结果以及每次选择更改时发生。当我们将列表框绑定到绑定源时，整行添加为 DataRowView。我们可以使用它来获取 Image 列中的数据。首先检查该字段是否为空。接下来转换为字节数组。获取字节数组并将其传递给 MemoryStream 的构造函数。需要处理流，因此它位于 Using 块中。最后可以将流分配给PictureBox.
Image属性
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Dim dt = GetDataFromSql()
Dim BndSrc As New BindingSource()
BndSrc.DataSource = dt
ListBox1.DisplayMember = "ItemName"
ListBox1.DataSource = BndSrc
TextBox1.DataBindings.Add("Text", BndSrc, "ItemID")
TextBox2.DataBindings.Add("Text", BndSrc, "ItemName")
TextBox3.DataBindings.Add("Text", BndSrc, "Details")
End Sub
Private Function GetDataFromSql() As DataTable
Dim dt As New DataTable
Using connection As New SqlConnection("Data Source=WXCQSDQSD\SQLEXPRESS;Initial Catalog=food;Integrated Security = True"),
cmd As New SqlCommand("select * FROM Items", connection)
connection.Open()
Using reader = cmd.ExecuteReader
dt.Load(reader)
End Using
End Using
Return dt
End Function
Private Sub ListBox1_SelectedIndexChanged(sender As Object, e As EventArgs) Handles ListBox1.SelectedIndexChanged
Dim row = DirectCast(ListBox1.SelectedItem, DataRowView)
If row("Image") IsNot Nothing Then
Dim b() As Byte = DirectCast(row("Image"), Byte()) '< ------ Cast the field to a Byte array.
Using ms As New System.IO.MemoryStream(b)
PictureBox1.Image = System.Drawing.Image.FromStream(ms)
End Using
Else
PictureBox1.Image = Nothing
End If
End Sub
编辑
我将代码切换到可用于测试的数据库。尽管它不是您的数据库，但我相信您将能够遵循代码。
这是我的数据库的架构。
主要区别是我将 DataTable 移动到 class 级别变量，因此可以从所有方法中看到它。我将 GetDataFromSql 更改为 Sub。它将数据添加到 class 级别 DataTable (Bounddt)。 AddItem 方法首先从文件中获取 Byte()。该行被添加到 DataTable 中，带有一个 Object 数组，其中的元素与 DataTable 匹配。
Private Bounddt As New DataTable
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
GetDataFromSql()
Dim BndSrc As New BindingSource()
BndSrc.DataSource = Bounddt
ListBox1.DisplayMember = "CustomerID"
ListBox1.DataSource = BndSrc
TextBox1.DataBindings.Add("Text", BndSrc, "CustomerID")
TextBox2.DataBindings.Add("Text", BndSrc, "CustomerName")
End Sub
Private Sub GetDataFromSql()
Using connection As New SqlConnection("Data Source=****;Initial Catalog='Small Database';Integrated Security=True;Connect Timeout=30;Encrypt=False;TrustServerCertificate=False;ApplicationIntent=ReadWrite;MultiSubnetFailover=False"),
cmd As New SqlCommand("select * FROM Sales.Customer", connection)
connection.Open()
Using reader = cmd.ExecuteReader
Bounddt.Load(reader)
End Using
End Using
'Return dt
End Sub
Private Sub ListBox1_SelectedIndexChanged(sender As Object, e As EventArgs) Handles ListBox1.SelectedIndexChanged
Dim row = DirectCast(ListBox1.SelectedItem, DataRowView)
If row("Picture") IsNot Nothing Then
Dim b() As Byte = DirectCast(row("Picture"), Byte()) '< ------ Cast the field to a Byte array.
Using ms As New System.IO.MemoryStream(b)
PictureBox1.Image = System.Drawing.Image.FromStream(ms)
End Using
Else
PictureBox1.Image = Nothing
End If
End Sub
Private Sub AddItem()
Dim picture = GetByteArr("C:\Users\maryo\OneDrive\Documents\Graphics\Animals\squirrel.png")
Bounddt.Rows.Add({5, "George", 74, 62, "George", picture})
End Sub
Private Function GetByteArr(path As String) As Byte()
Dim img = Image.FromFile(path)
Dim arr As Byte()
Dim imgFor As Imaging.ImageFormat
Dim extension = path.Substring(path.LastIndexOf(".") + 1)
'There is a longer list of formats available in ImageFormat
Select Case extension
Case "png"
imgFor = Imaging.ImageFormat.Png
Case "jpg", "jpeg"
imgFor = Imaging.ImageFormat.Jpeg
Case "bmp"
imgFor = Imaging.ImageFormat.Bmp
Case Else
MessageBox.Show("Not a valid image format")
Return Nothing
End Select
Using ms As New MemoryStream
img.Save(ms, imgFor)
arr = ms.ToArray
End Using
Return arr
End Function
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
AddItem()
End Sub