Renaming a File/Folder inside a Zip File in Java?

Question

I have a zip file containing a folder structure like

• main-folder/
  • subFolder1/
  • subFolder2/
  • subFolder3/
    • file3.1
    • fi

Answer 1

I know you asked about Java but just for archival purposes I thought I would contribute a note about .NET.

DotNetZip is a .NET library for zip files that allows renaming of entries. As Tom Hawtin's reply states, directories are not first-class entities in the zip file metadata, and as a result, no zip libraries that I know of expose a "rename directory" verb. But some libraries allow you to rename all the entries that have names that indicate a particular directory, which gives you the result you want.

In DotNetZip, it would look like this:

 var regex = new Regex("/OldDirName/.*$");
 int renameCount= 0;
 using (ZipFile zip = ZipFile.Read(ExistingZipFile))
 {
    foreach (ZipEntry e in zip)
    {
        if (regex.IsMatch(e.FileName))
        {
            // rename here
            e.FileName = e.FileName.Replace("/OldDirName/", "/NewDirName/");
            renameCount++;
        }
    }
    if (renameCount > 0)
    {
        zip.Comment = String.Format("This archive has been modified. {0} entries have been renamed.", renameCount);
        // any changes to the entries are made permanent by Save()
        zip.Save();  // could also save to a new zip file here
    }
 }

You can also add or remove entries, inside the using clause.

If you save to the same file, then DotNetZip rewrites only the changed metadata - the entry headers and the central directory records for renamed entries, which saves time with large archives. If you save to a new file or stream, then all of the zip data gets written.