encoding - Add non-ASCII file names to zip in Java

Question

What is the best way to add non-ASCII file names to a zip file using Java, in such a way that the files can be properly read in both Windows and Linux?

Here is one attempt, adapted from https://truezip.dev.java.net/tutorial-6.html#Example, which works in Windows Vista but fails in Ubuntu Hardy. In Hardy the file name is shown as abc-ЖДФ.txt in file-roller.

import java.io.IOException;
import java.io.PrintStream;

import de.schlichtherle.io.File;
import de.schlichtherle.io.FileOutputStream;

public class Main {

    public static void main(final String[] args) throws IOException {

        try {
            PrintStream ps = new PrintStream(new FileOutputStream(
                    "outer.zip/abc-???.txt"));
            try {
                ps.println("The characters ??? works here though.");
            } finally {
                ps.close();
            }
        } finally {
            File.umount();
        }
    }
}

Unlike java.util.zip, truezip allows specifying zip file encoding. Here's another sample, this time explicitly specifiying the encoding. Neither IBM437, UTF-8 nor ISO-8859-1 works in Linux. IBM437 works in Windows.

import java.io.IOException;

import de.schlichtherle.io.FileOutputStream;
import de.schlichtherle.util.zip.ZipEntry;
import de.schlichtherle.util.zip.ZipOutputStream;

public class Main {

    public static void main(final String[] args) throws IOException {

        for (String encoding : new String[] { "IBM437", "UTF-8", "ISO-8859-1" }) {
            ZipOutputStream zipOutput = new ZipOutputStream(
                    new FileOutputStream(encoding + "-example.zip"), encoding);
            ZipEntry entry = new ZipEntry("abc-???.txt");
            zipOutput.putNextEntry(entry);
            zipOutput.closeEntry();
            zipOutput.close();
        }
    }
}

Answer 1

The encoding for the File-Entries in ZIP is originally specified as IBM Code Page 437. Many characters used in other languages are impossible to use that way.

The PKWARE-specification refers to the problem and adds a bit. But that is a later addition (from 2007, thanks to Cheeso for clearing that up, see comments). If that bit is set, the filename-entry have to be encoded in UTF-8. This extension is described in 'APPENDIX D - Language Encoding (EFS)', that is at the end of the linked document.

For Java it is a known bug, to get into trouble with non-ASCII-characters. See bug #4244499 and the high number of related bugs.

My colleague used as workaround URL-Encoding for the filenames before storing them into the ZIP and decoding after reading them. If you control both, storing and reading, that may be a workaround.

EDIT: At the bug someone suggests using the ZipOutputStream from Apache Ant as workaround. This implementation allows the specification of an encoding.