form3.vb

编程环境VB.NET2005 多线程下载

Imports System.IO
Imports System.Data.OleDb

Public Class Form3

    Private Sub Form3_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim s As String = "下载数据" & ChrW(928) & ChrW(931)
        Dim encoding As System.Text.Encoding = encoding.Unicode
        Dim b As Byte() = encoding.GetBytes(s.ToCharArray) ',0, 1)
        b = System.Text.Encoding.Unicode.GetBytes(s.ToCharArray)
        Using conn As New Data.OleDb.OleDbConnection(connStr)
            Dim com As New Data.OleDb.OleDbCommand("", conn)
            Dim comtext As String
            com.Parameters.Add("@bin", OleDb.OleDbType.VarBinary).Value = System.Text.Encoding.Unicode.GetBytes(s.ToCharArray)
            'comtext = String.Format("UPDATE 下载数据 SET Status={0} , Length={1},threadcount={2},thread='{3}' WHERE MD5={4}", dtData.status, dtData.Length, dtData.downThreadAmount, dtData.thData, Me.MyTaskInfo.md5)
            comtext = "INSERT INTO ttt (aaa) VALUES (@bin)"
            com.CommandText = comtext
            conn.Open()
            'com.ExecuteNonQuery()
            com.Dispose()
        End Using
        LoadIniData()
    End Sub
    Sub LoadIniData()
        Dim b() As Byte = Nothing
        Using conn As New Data.OleDb.OleDbConnection(connStr)
            Dim com As New Data.OleDb.OleDbCommand("", conn)
            com.CommandText = "SELECT * FROM ttt WHERE ID=17"
            conn.Open()
            Dim dr As OleDb.OleDbDataReader = com.ExecuteReader
            While dr.Read()
                b = CType(dr.Item("aaa"), Byte())
            End While
        End Using
        'ShowArray(a)
        Console.WriteLine(BinToStr(b) & " ************:::::::")
    End Sub
    Private Sub cmdSave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdsave.Click
        Dim str As New MemoryStream
        'save the image to the stream in .Jpeg format
        pic.Image.Save(str, Imaging.ImageFormat.Jpeg)
        Dim buffer(CInt(str.Length - 1)) As Byte
        str.Position = 0
        str.Read(buffer, 0, CInt(str.Length))
        'create a connection to the images database in the root folder or our machine
        Dim con As New OleDbConnection(connStr)
        'create a command object based on this command
        Dim cmd As New OleDbCommand("UPDATE ttt SET aaa = @ProductImage ", con)
        cmd.CommandType = CommandType.Text
        Dim prmPic As New OleDbParameter 'done step by step here 
        With prmPic
            .ParameterName = "@ProductImage" 'the name used in the query for the parameter
            .OleDbType = OleDbType.Binary 'set the database type
            .Value = buffer 'assign the contents of the buffer to the value of the parameter
        End With
         cmd.Parameters.Add(prmPic) 'add the parameter to the command
        Try
            'open the connection
            con.Open()
            'execute the command
            cmd.ExecuteNonQuery()
            'report success and clear the image to allow the user to select another image
            MessageBox.Show("The Record was saved successfully.")
            pic.Image = Nothing
        Catch ex As Exception
            MessageBox.Show("There was a problem saving the Record." & ControlChars.CrLf & ex.Message)
        Finally
            'close the connection and free the memory we were using
            If con.State = ConnectionState.Open Then con.Close()
            con.Dispose() : cmd.Dispose()
            con = Nothing : cmd = Nothing : prmPic = Nothing
        End Try
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim s As String = "QWERT下载数据" & ChrW(928) & ChrW(931)
        Dim encoding As System.Text.Encoding = encoding.Unicode
        Dim b As Byte() = encoding.GetBytes(s.ToCharArray)
        b = System.Text.Encoding.Unicode.GetBytes(s.ToCharArray)
        Using conn As New Data.OleDb.OleDbConnection(connStr)
            Dim com As New Data.OleDb.OleDbCommand("", conn)
            Dim comtext As String
            com.Parameters.Add("@bin", OleDb.OleDbType.VarBinary).Value = System.Text.Encoding.Unicode.GetBytes(s.ToCharArray)
            comtext = "UPDATE ttt SET aaa =@bin WHERE ID=17"
            com.CommandText = comtext
            conn.Open()
            com.ExecuteNonQuery()
            com.Dispose()
        End Using
    End Sub
End Class