Hello world example on VFS: create a zip file from scratch

Question

I would like to create a zip file with Commons VFS2 library. I know how to copy a file when using file prefix but for zip files write and read are not implemented.

fileSystemManager.resolveFile("path comes here")-method fails when I try path zip:/some/file.zip when file.zip is an non-existing zip-file. I can resolve an existing file but non-existing new file fails.

So how to create that new zip file then? I cannot use createFile() because it is not supported and I cannot create the FileObject before this is to be called.

The normal way is to create FileObject with that resolveFile and then call createFile for the object.

Answer 1

The answer to my need is the following code snippet:

// Create access to zip.
FileSystemManager fsManager = VFS.getManager();
FileObject zipFile = fsManager.resolveFile("file:/path/to/the/file.zip");
zipFile.createFile();
ZipOutputStream zos = new ZipOutputStream(zipFile.getContent().getOutputStream());

// add entry/-ies.
ZipEntry zipEntry = new ZipEntry("name_inside_zip");
FileObject entryFile = fsManager.resolveFile("file:/path/to/the/sourcefile.txt");
InputStream is = entryFile.getContent().getInputStream();

// Write to zip.
byte[] buf = new byte[1024];
zos.putNextEntry(zipEntry);
for (int readNum; (readNum = is.read(buf)) != -1;) {
   zos.write(buf, 0, readNum);
}

After this you need to close the streams and it works!

Answer 2

In fact, it is possible to create zip files uniquely from Commons-VFS by using the following idio :

        destinationFile = fileSystemManager.resolveFile(zipFileName);
        // destination is created as a folder, as the inner content of the zip
        // is, in fact, a "virtual" folder
        destinationFile.createFolder();

        // then add files to that "folder" (which is in fact a file)

        // and finally close that folder to have a usable zip
        destinationFile.close();

        // Exception handling is left at user discretion