Question

I’ve been trying to write a program in java that can download a number of .gz files from an ftp server online for me. Here’s what I’ve been using:

public static void main(String[] args) throws IOException {
    URL url = new URL("ftp://ftp.ncbi.nih.gov/pub/geo/DATA/SOFT/by_series/GSE10/");
    URLConnection con = url.openConnection();
    BufferedInputStream in = new BufferedInputStream(con.getInputStream());
    FileOutputStream out = new FileOutputStream("GSE10_family.soft.gz");

    int i = 0;
    byte[] bytesIn = new byte[3000000];
    while ((i = in.read(bytesIn)) >= 0) {
        out.write(bytesIn, 0, i);
    }
    out.close();
    in.close();

}

The program runs and downloads the file just fine. However, when I try to uncompress the .gz file, it unzips as a .cpgz file which then creates an endless cycle of .cpgz to .gz and so forth.

When I download this file manually, it unzips and everything perfectly fine, so I know it isn’t a problem with the file.

Any suggestions would be greatly appreciated! Thank you so much!

Answer 1

When I print out the contents of the file you download it appears as

-r--r--r--   1 ftp      anonymous  2311751 Jan 29 16:45 GSE10_family.soft.gz

If I download the file instead of the directory I get a gzip file.

$ gunzip GSE10_family.soft.gz

$ ls -l GSE10_family.soft
----------+ 1 peter None 7698802 2011-06-09 16:24 GSE10_family.soft