How to decode zip file and save it in vb.net?

Question

I am creating a project where a zip file is base 64 encoded and then the file is decoded and saved, but when I unzip the file it gives a corrupted file error.

Dim zip As New Xs_UnZipFilesCompat
''Encode()
Dim base64encoded As String
Using r As StreamReader = New StreamReader(File.OpenRead("E:\zip_test.zip"))
    Dim data As Byte() = System.Text.ASCIIEncoding.ASCII.GetBytes(r.ReadToEnd())
    base64encoded = System.Convert.ToBase64String(data)
    r.Dispose()
End Using

'decode --> write back
Using w As StreamWriter = New StreamWriter(File.Create("e:\stcRepositorio\Entrena_To_Art\Enviar\testDEco.zip"))
    Dim data As Byte() = System.Convert.FromBase64String(base64encoded)
    w.Write(System.Text.ASCIIEncoding.ASCII.GetString(data))
    w.Dispose()
End Using

I can't find the solution

I'm confused why you're using ASCII at all. Just take the bytes from the zip file and convert them to base64. Convert them back the same way, as in [Decode base64 to image in vb.net](https://stackoverflow.com/q/49507221/215552) — Heretic Monkey, Dec 14 '22 at 21:43
Don't call `.Dispose()` for an item that was already created in a `Using` block. Ensuring Dispose() is always called for you at the appropriate time is the whole point of the Using block in the first place. — Joel Coehoorn, Dec 14 '22 at 22:00

Joel Coehoorn · Accepted Answer · 2022-12-14T21:54:22.653

The encode is not correct. Specifically, this line:

Dim data As Byte() = System.Text.ASCIIEncoding.ASCII.GetBytes(r.ReadToEnd())

You definitely don't want to read a file with a *.zip extension as if it were made of ASCII characters. Replace it with this:

Dim data As Byte() = System.IO.File.ReadAllBytes(fileName)

Which means you also no longer need the StreamReader, so we end up with this:

Public Function Encode(fileName As String) As String
    Return Convert.ToBase64String(IO.File.ReadAllBytes(fileName))
End Function

Then the Decode would look like this:

Public Sub Decode(fileName As String, base64Data As String)
    IO.File.WriteAllBytes(fileName, Convert.FromBase64String(base64Data))
End Sub

And you could call them like this:

Dim base64encoded As String = Encode("E:\zip_test.zip")
Decode("e:\stcRepositorio\Entrena_To_Art\Enviar\testDEco.zip", base64encoded)

Or we can write it without the methods like this:

Dim base64encoded As String = Convert.ToBase64String(IO.File.ReadAllBytes("E:\zip_test.zip"))
IO.File.WriteAllBytes("e:\stcRepositorio\Entrena_To_Art\Enviar\testDEco.zip", Convert.FromBase64String(base64encoded))

But it seems like that all reduces down to this:

IO.File.Copy("E:\zip_test.zip", "e:\stcRepositorio\Entrena_To_Art\Enviar\testDEco.zip")

How to decode zip file and save it in vb.net?

1 Answers1