在 ASP.NET VB 中上传图像

Question

有什么方法可以用ASP.NET 和VB 上传图片吗？

我需要ASP.NET 一侧的“上传”按钮。

SQL server 2008 的表中已经有一个图像字段。

有什么办法可以做到吗？

Answer 1

1. 添加fileupload 控件：

<asp:FileUpload runat="server" id="FileUpload1" />

1. 添加一个上传按钮，并将其放在按钮单击事件处理程序中：

    Protected Sub btnUpload_Click(ByVal sender As Object, ByVal e As EventArgs)

        Dim bldgIDNum As Int32 = FormView_Building.SelectedValue
        If FileUpload1.PostedFile IsNot Nothing AndAlso FileUpload1.PostedFile.FileName <> "" Then
            Dim imageSize As Byte() = New Byte(FileUpload1.PostedFile.ContentLength - 1) {}
            Dim uploadedImage__1 As HttpPostedFile = FileUpload1.PostedFile
            uploadedImage__1.InputStream.Read(imageSize, 0, CInt(FileUpload1.PostedFile.ContentLength))

            ' Create SQL Connection 
            Dim con As New SqlConnection()
            con.ConnectionString = ConfigurationManager.ConnectionStrings("ConnectionString").ConnectionString

            ' Create SQL Command 

            Dim cmd As New SqlCommand()
            cmd.CommandText = "INSERT INTO Table (PrimaryKey,ImageData) VALUES (@PrimaryKey,@ImageData)"
            cmd.CommandType = CommandType.Text
            cmd.Connection = con

            Dim PrimaryKey As New SqlParameter("@PrimaryKey", SqlDbType.Int, 32)
            PrimaryKey.Value = (however you want to get it)

            Dim UploadedImage__2 As New SqlParameter("@ImageData", SqlDbType.Image, imageSize.Length)
            UploadedImage__2.Value = imageSize
            cmd.Parameters.Add(UploadedImage__2)
            con.Open()
            Dim result As Integer = cmd.ExecuteNonQuery()
            con.Close()
            If result > 0 Then
                lblMessage.Text = "File Uploaded"
            End If

        End If

        ListView_BldgImages.DataBind()

    End Sub

1. 数据库列ImageData应该是varbinary(max)

2. 使用以下内容创建一个名为 Handler_Image.ashx 的处理程序：

Imports System
Imports System.Web
Imports System.Configuration
Imports System.Data.SqlClient

Public Class Handler_Image : Implements IHttpHandler
    
    Public Sub ProcessRequest(ByVal context As HttpContext) Implements IHttpHandler.ProcessRequest
        Dim con As New SqlConnection()
        con.ConnectionString = ConfigurationManager.ConnectionStrings("ConnectionString").ConnectionString
        
        ' Create SQL Command 
        
        Dim cmd As New SqlCommand()
        cmd.CommandText = "Select ImageData from Table where PrimaryKey =@PrimaryKey"
        cmd.CommandType = System.Data.CommandType.Text
        cmd.Connection = con
        
        Dim ID As New SqlParameter("@PrimaryKey", System.Data.SqlDbType.Int)
        ID.Value = context.Request.QueryString("PrimaryKey")
        cmd.Parameters.Add(ID)
        con.Open()
        Dim dReader As SqlDataReader = cmd.ExecuteReader()
        dReader.Read()
        context.Response.BinaryWrite(DirectCast(dReader("ImageData"), Byte()))
        dReader.Close()
        con.Close()
    End Sub
 
    Public ReadOnly Property IsReusable() As Boolean Implements IHttpHandler.IsReusable
        Get
            Return False
        End Get
    End Property

End Class

5. 使用具有以下属性的图像控件显示图像： ImageUrl='<%# "Handler_Image.ashx?PrimaryKey=" & Eval("PrimaryKey")%>'

6. 替换connectionstring、表名和主键以适合您的应用程序