Convert zip file to gzip and write to hdfs

Question

I have a zip file which I want to convert to gzip and write it back to the filesystem. How can I do this?

I already have this code to compress a file to gzip:

private static void compressGzipFile(String file, String gzipFile) {
    try {
        FileInputStream fis = new FileInputStream(file);
        FileOutputStream fos = new FileOutputStream(gzipFile);
        GZIPOutputStream gzipOS = new GZIPOutputStream(fos);
        byte[] buffer = new byte[1024];
        int len;

        while ((len=fis.read(buffer)) != -1) {
            gzipOS.write(buffer, 0, len);
        }

        // Close resources
        gzipOS.close();
        fos.close();
        fis.close();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

Now I need code to convert the zip file into a gzip file.

You can't convert a zip file to a gzip file, because zip-files can contain files, while gzip doesn't. Do you want to gzip the zip file instead (which I doubt will be effective). — Mark Rotteveel, Feb 14 '19 at 18:30

score -1 · Answer 1 · answered Feb 14 '19 at 16:09

Why not just pipe a ZipInputStream directly into a GZIPOutputStream?

private static void convertZipToGzip(String zipFile, String gzipFile) {
    try (ZipInputStream zipIS = new ZipInputStream(file),
         GZIPOutputStream gzipOS = new GZIPOutputStream(gzipFile)) {
        zipIS.transferTo(gzipOS);
    } catch (IOException e) {
        e.printStackTrace();
    }
}

This solution takes advantage of Java 9’s incredibly useful InputStream#transferTo(OutputStream). If you’re not yet using Java 9, you’ll need to manually copy the bytes from one stream to the other, or use Apache Commons IOUtils’ IOUtils.copy(InputStream, OutputStream).

the code in the answer take the zip file and compress it to gzip, I looking for code the take the zip content and compress it go gzip — Ya Ko, Feb 14 '19 at 17:16

Convert zip file to gzip and write to hdfs

1 Answers1