VB.NET 图片与BASE64互转_dim dlgbody as message;-优快云博客

本文介绍了一种使用Visual Basic实现的图片文件与Base64编码字符串相互转换的方法。通过两个函数ImgToBase64String和Base64StringToImage，可以将图片文件转换为Base64编码字符串，或将Base64编码字符串还原为图片。这两个函数能够处理多种图片格式，如.jpg、.bmp、.gif、.png等。

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 Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click

        Dim dlg As OpenFileDialog = New OpenFileDialog()
        dlg.Multiselect = True
        dlg.Title = "选择要转换的图片"
        dlg.Filter = "Image files (*.jpg,*.bmp,*.gif,*.png)|*.jpg;*.jpeg;*.gif;*.bmp|AllFiles (*.*)|*.*"

        If DialogResult.OK = dlg.ShowDialog() Then

            For i As Integer = 0 To dlg.FileNames.Length - 1

                RichTextBox1.Text = ImgToBase64String(dlg.FileNames(i).ToString())

            Next



        End If



    End Sub

Function ImgToBase64String(ByVal Imagefilename As String)
        Try
            Dim bmp As Bitmap = New Bitmap(Imagefilename)
            Me.PictureBox1.Image = bmp
            Dim fs As FileStream = New FileStream(Imagefilename & "_BASE64" & ".txt", FileMode.Create)
            Dim sw As StreamWriter = New StreamWriter(fs)
            Dim ms As MemoryStream = New MemoryStream()
            bmp.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg)
            Dim arr As Byte() = New Byte(ms.Length - 1) {}
            ms.Position = 0
            ms.Read(arr, 0, CInt(ms.Length))
            ms.Close()
            Dim strbaser64 As String = Convert.ToBase64String(arr)

            sw.Write(strbaser64)
            sw.Close()
            fs.Close()
            Return strbaser64

        Catch ex As Exception
            MessageBox.Show("ImgToBase64String 转换失败" & vbLf & "Exception:" & ex.Message)
        End Try
    End Function

 Private Sub Button4_Click(sender As Object, e As EventArgs) Handles Button4.Click

        Dim dlg As OpenFileDialog = New OpenFileDialog()
        dlg.Multiselect = True
        dlg.Title = "选择要转换的base64编码的文本"
        dlg.Filter = "txt files|*.txt"

        If DialogResult.OK = dlg.ShowDialog() Then

            For i As Integer = 0 To dlg.FileNames.Length - 1

                Base64StringToImage(dlg.FileNames(i).ToString())
                RichTextBox1.Text = File.ReadAllText(dlg.FileNames(i))
            Next

        End If

    End Sub

Private Sub Base64StringToImage(ByVal txtFileName As String)
        Try
            Dim ifs As FileStream = New FileStream(txtFileName, FileMode.Open, FileAccess.Read)
            Dim sr As StreamReader = New StreamReader(ifs)
            Dim inputStr As String = sr.ReadToEnd()
            Dim arr As Byte() = Convert.FromBase64String(inputStr)
            Dim ms As MemoryStream = New MemoryStream(arr)
            Dim bmp As Bitmap = New Bitmap(ms)
            ms.Close()
            sr.Close()
            ifs.Close()
            Me.PictureBox1.Image = bmp

            'If File.Exists(txtFileName) Then
            ' File.Delete(txtFileName)
            'End If

        Catch ex As Exception
            MessageBox.Show("Base64StringToImage 转换失败" & vbLf & "Exception：" & ex.Message)
        End Try
    End Sub