vb.net openfile 修改编码

在VB.NET中，如果你需要修改打开文件的默认字符编码，通常是在读取文件内容之前设置`StreamReader`或`FileReader`的`Encoding`属性。例如：

Dim filePath As String = "path_to_your_file.txt"
Dim encoding As Encoding = Encoding.UTF8 ' 或者选择其他编码，如(Encoding.ASCII, Encoding.Unicode等)

Using reader As New StreamReader(filePath, encoding)
    Dim content As String = reader.ReadToEnd()
    ' Now you can work with the decoded content
End Using

在这里，`StreamReader`会按照指定的`Encoding`解析文件内容。如果文件实际编码不是你指定的，可能会导致乱码问题。

如果你已经打开了文件，并想改变它的当前编码，可以这样做：

Dim fileStream As FileStream = File.OpenRead(filePath)
Dim originalReader As New StreamReader(fileStream)
Dim text原有编码 = originalReader.ReadToEnd()

fileStream.Seek(0, SeekOrigin.Begin) ' Move back to beginning of stream
Dim newEncoding As Encoding = Encoding.UTF8 ' 新的编码
Dim modifiedReader As New StreamReader(fileStream, newEncoding)
Dim contentAsNewEncoding As String = modifiedReader.ReadToEnd()

originalReader.Close() ' Close the original reader
modifiedReader.Close() ' And the one with new encoding

' Now, contentAsNewEncoding contains the content read using the new encoding.