关于数组：将base64解码为vb.net中的映像


Decode base64 to image in vb.net

我一直在网上搜索，没有找到答案。你想告诉我，如何从base64解码为Image样的线图吗？我一直在尝试先从base64数组转换为Byte数组，然后从Byte数组转换为Image。

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Private Function convertbytetoimage(ByVal BA As Byte())
     Dim ms As MemoryStream = New MemoryStream(BA)
     image = Image.FromStream(ms) 'I always get wrong in this line.
     Return image
 End Function
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看看您的代码，您的问题可能是使用变量名image，而不是像_image这样的东西。

记住，VB与C#和其他编程语言不区分大小写。

在您的代码中，我假设您将image变量定义为image。

要使用静态Image.FromStream(ms)，您要么使用image的完全限定名，要么更改变量名。

以下是修复代码的方法：

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Private Function convertbytetoimage(ByVal BA As Byte())
    Dim ms As MemoryStream = New MemoryStream(BA)
    image = System.Drawing.Image.FromStream(ms)
    Return image
End Function

或者，您可以通过更改变量名来执行此操作，例如：

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Dim _image as Image

Private Function convertbytetoimage(ByVal BA As Byte())
    Dim ms As MemoryStream = New MemoryStream(BA)
    _image = Image.FromStream(ms)
    Return _image
End Function

更新：

您可以尝试将Byte数组转换为image，也可以使用ImageConvertor：

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Private Function convertbytetoimage(ByVal BA As Byte())
    Dim converter As ImageConverter = New ImageConverter()
    _image = CType(converter.ConvertFrom(BA), Image)
    Return _image
End Function

更新2：

因为看起来主要的问题是base64字符串。请看我的小演示，它将image从PictureBox中转换为base64字符串，然后转换为Byte数组，最后转换为image。

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Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
    Dim base64String = ConvertImageToBase64String() 'Using Functions To Make the code tidier
    Dim byteArray = ConvertBase64ToByteArray(base64String) 'Using Functions To Make the code tidier
    Dim image = convertbytetoimage(byteArray) 'Using Functions To Make the code tidier
    PictureBox2.Image = image 'since we're using a small windows form app, we'll set back the image to a second picture box.
End Sub

Public Function ConvertImageToBase64String() As String
    Using ms As New MemoryStream()
        PictureBox1.Image.Save(ms, System.Drawing.Imaging.ImageFormat.Png) 'We load the image from first PictureBox in the MemoryStream
        Dim obyte = ms.ToArray() 'We tranform it to byte array..

        Return Convert.ToBase64String(obyte) 'We then convert the byte array to base 64 string.
    End Using
End Function

Public Function ConvertBase64ToByteArray(base64 As String) As Byte()
    Return Convert.FromBase64String(base64) 'Convert the base64 back to byte array.
End Function

'Here's the part of your code (which works)
Private Function convertbytetoimage(ByVal BA As Byte())
    Dim ms As MemoryStream = New MemoryStream(BA)
    Dim image = System.Drawing.Image.FromStream(ms)
    Return image
End Function

请注意，在将image转换为base64字符串后，它看起来是这样的(请记住，每个图像都是不同的，因此不会得到相同的字符串)：

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

如果你看这个字符串的前5个字符，你会发现它等于/9j/4，这意味着这个字符串所代表的文件是PNG文件，你可以看看我以前的回答，看看如何验证base64字符串。

另一个注意事项是，我使用了一个小的PNG图像，因此我使用了下一种格式：

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PictureBox1.Image.Save(ms, System.Drawing.Imaging.ImageFormat.Png)

如果您有其他格式，并且希望使用相同的代码，请确保更改格式。

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