(VB.NET) Understanding ZIP Entry Types and the ZIP Object Lifecycle

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This example demonstrates how the Chilkat.Zip object manages entries before and after a ZIP archive is written.

The example shows:

• How file references are added from the local filesystem using AppendFilesEx
• How in-memory entries are added using AddString
• How ZIP entry types change as the ZIP archive progresses from an in-memory staging object to an actual written .zip file
• How additional entries can continue to be added even after the ZIP archive has already been written

The example also demonstrates the meaning of the different ZipEntry.EntryType values:

• 1 — File references in the local filesystem that have not yet been processed
• 2 — In-memory data entries
• 0 — Entries mapped to an existing open ZIP archive

This example is useful for understanding how the Chilkat.Zip class internally stages entries prior to writing the final ZIP archive.

Note: This example requires Chilkat v11.0.0 or greater.

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Dim success As Boolean = False

success = False

Dim zip As New Chilkat.Zip

Dim zipPath As String = "c:/temp/out.zip"

' Start a new Zip object and set the output path.
' This does not create the .zip file yet.  It only initializes the Zip object
' and records the filename to be used later when WriteZip is called.
zip.NewZip(zipPath)

' Add references to files in the local filesystem.
' AppendFilesEx does not read, compress, or store the file contents at this point.
' It only adds file references to the Zip object.  The referenced files are
' read and compressed later, when WriteZip is called.
Dim recurse As Boolean = True
Dim saveExtraPath As Boolean = False
Dim archiveOnly As Boolean = False
Dim includeHidden As Boolean = True
Dim includeSystem As Boolean = False
success = zip.AppendFilesEx("c:/temp/files_to_zip",recurse,saveExtraPath,archiveOnly,includeHidden,includeSystem)
If (success = False) Then
    Debug.WriteLine(zip.LastErrorText)
    Exit Sub
End If


' We can inspect the entries that have been added to the Zip object.
' At this stage, the entries are still references to files in the local filesystem.
Dim entry As New Chilkat.ZipEntry
Dim count As Integer = zip.NumEntries
Dim i As Integer = 0
While i < count
    zip.EntryAt(i,entry)
    Debug.WriteLine(entry.FileName & " entryType = " & entry.EntryType)
    i = i + 1
End While
Debug.WriteLine("----")

' Sample output for the above loop:
' 
' hamlet.xml entryType = 1
' hello.pdf entryType = 1
' ...
' ...
' 
' entryType = 1 means "File Entry".
' A File Entry is a reference to a file in the local filesystem.
' The file data has not yet been read into the Zip object.
' 
' Possible entryType values:
' 
' 0 - Mapped Entry:
'     An entry that already exists in an open .zip file.
' 
' 1 - File Entry:
'     A file in the local filesystem that has been referenced, but not yet
'     read or compressed.  These entries are added by methods such as
'     AppendFiles, AppendFilesEx, and AddFile.
' 
' 2 - Data Entry:
'     An entry containing uncompressed data already held in memory.
'     These entries are added by methods such as AddData, AddString,
'     AddSb, AddBd, and AddEncoded.
' 
' 3 - Null Entry:
'     An entry that no longer exists in the .zip.
' 
' 4 - New Directory Entry:
'     A directory entry added by calling AddEmpty.

' Additional entries can still be added before the .zip is written.
' This entry is created from an in-memory string, so it is a Data Entry
' rather than a File Entry.
zip.AddString("helloWorld.txt","Hello World","utf-8")

' Inspect the Zip object again before writing.
' The file references are still entryType = 1.
' The in-memory string entry is entryType = 2.
count = zip.NumEntries
i = 0
While i < count
    zip.EntryAt(i,entry)
    Debug.WriteLine(entry.FileName & " entryType = " & entry.EntryType)
    i = i + 1
End While
Debug.WriteLine("----")

' Sample output:
' 
' hamlet.xml entryType = 1
' hello.pdf entryType = 1
' ...
' ...
' helloWorld.txt entryType = 2
' 
' helloWorld.txt has entryType = 2 because its contents came from memory.
' It is not a reference to a file in the local filesystem.

' ----------------------------------------------------------------------------
' Write the Zip object to the .zip file.
' 
' During this call, Chilkat reads the referenced files from the local filesystem,
' compresses the data as needed, and writes the final .zip archive.
zip.FileName = zipPath
success = zip.WriteZip()
If (success = False) Then
    Debug.WriteLine(zip.LastErrorText)
    Exit Sub
End If


' After WriteZip returns successfully, the .zip file is written and remains
' open in the Zip object.  The entries now correspond to entries in the
' currently open .zip archive.
count = zip.NumEntries
i = 0
While i < count
    zip.EntryAt(i,entry)
    Debug.WriteLine(entry.FileName & " entryType = " & entry.EntryType)
    i = i + 1
End While
Debug.WriteLine("----")

' Sample output:
' 
' hamlet.xml entryType = 0
' hello.pdf entryType = 0
' ...
' ...
' helloWorld.txt entryType = 0
' 
' entryType = 0 means "Mapped Entry".
' A Mapped Entry is an entry that exists in an open .zip file.

' ----------------------------------------------------------------------------
' The .zip remains open after WriteZip, so additional entries can still be added.
' 
' This adds another in-memory string entry to the currently open Zip object.
zip.AddString("helloWorld2.txt","Hello World 2","utf-8")

' Write the .zip again to include the newly added entry.
success = zip.WriteZip()
If (success = False) Then
    Debug.WriteLine(zip.LastErrorText)
    Exit Sub
End If


' Inspect the entries one final time.
' After the second WriteZip, the new entry is also mapped to the open .zip file.
count = zip.NumEntries
i = 0
While i < count
    zip.EntryAt(i,entry)
    Debug.WriteLine(entry.FileName & " entryType = " & entry.EntryType)
    i = i + 1
End While
Debug.WriteLine("----")

' Sample output:
' 
' hamlet.xml entryType = 0
' hello.pdf entryType = 0
' ...
' ...
' helloWorld.txt entryType = 0
' helloWorld2.txt entryType = 0

' Close the open .zip archive and clear the Zip object.
zip.CloseZip()

Debug.WriteLine("Success")