كيفية ضغط الملفات وتحويلها الى Zip ؟؟

' The following code example shows how to use the GZipStream class to compress and decompress a file.

' Visual Basic

Imports System

Imports System.IO

Imports System.IO.Compression

Public Class GZipTest

Shared msg As String

Private Const buffer_size As Integer = 100

Public Shared Function ReadAllBytesFromStream(ByVal stream As Stream, ByVal buffer() As Byte) As Integer

' Use this method is used to read all bytes from a stream.

Dim offset As Integer = 0

Dim totalCount As Integer = 0

While True

Dim bytesRead As Integer = stream.Read(buffer, offset, buffer_size)

If bytesRead = 0 Then

Exit While

End If

offset += bytesRead

totalCount += bytesRead

End While

Return totalCount

End Function 'ReadAllBytesFromStream

Public Shared Function CompareData(ByVal buf1() As Byte, ByVal len1 As Integer, ByVal buf2() As Byte, ByVal len2 As Integer) As Boolean

' Use this method to compare data from two different buffers.

If len1 <> len2 Then

msg = "Number of bytes in two buffer are different" & len1 & ":" & len2

MsgBox(msg)

Return False

End If

Dim i As Integer

For i = 0 To len1 - 1

If buf1(i) <> buf2(i) Then

msg = "byte " & i & " is different " & buf1(i) & "|" & buf2(i)

MsgBox(msg)

Return False

End If

Next i

msg = "All bytes compare."

MsgBox(msg)

Return True

End Function 'CompareData

Public Shared Sub GZipCompressDecompress(ByVal filename As String)

msg = "Test compression and decompression on file " & filename

MsgBox(msg)

Dim infile As FileStream

Try

' Open the file as a FileStream object.

infile = New FileStream(filename, FileMode.Open, FileAccess.Read, FileShare.Read)

Dim buffer(infile.Length - 1) As Byte

' Read the file to ensure it is readable.

Dim count As Integer = infile.Read(buffer, 0, buffer.Length)

If count <> buffer.Length Then

infile.Close()

msg = "Test Failed: Unable to read data from file"

MsgBox(msg)

Return

End If

infile.Close()

Dim ms As New MemoryStream()

' Use the newly created memory stream for the compressed data.

Dim compressedzipStream As New GZipStream(ms, CompressionMode.Compress, True)

compressedzipStream.Write(buffer, 0, buffer.Length)

' Close the stream.

compressedzipStream.Close()

msg = "Original size: " & buffer.Length & ", Compressed size: " & ms.Length

MsgBox(msg)

' Reset the memory stream position to begin decompression.

ms.Position = 0

Dim zipStream As New GZipStream(ms, CompressionMode.Decompress)

Dim decompressedBuffer(buffer.Length + buffer_size) As Byte

' Use the ReadAllBytesFromStream to read the stream.

Dim totalCount As Integer = GZipTest.ReadAllBytesFromStream(zipStream, decompressedBuffer)

msg = "Decompressed " & totalCount & " bytes"

MsgBox(msg)

If Not GZipTest.CompareData(buffer, buffer.Length, decompressedBuffer, totalCount) Then

msg = "Error. The two buffers did not compare."

MsgBox(msg)

End If

zipStream.Close()

Catch e As Exception

msg = "Error: The file being read contains invalid data."

MsgBox(msg)

End Try

End Sub 'GZipCompressDecompress

Public Shared Sub Main(ByVal args() As String)

Dim usageText As String = "Usage: GZIPTEST <inputfilename>"

'If no file name is specified, write usage text.

If args.Length = 0 Then

Console.WriteLine(usageText)

Else

If File.Exists(args(0)) Then

GZipCompressDecompress(args(0))

End If

End If

End Sub 'Main

End Class 'GZipTest

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