Java: Zipinputstream to Zipoutputstream leads to "end-of-central-directory signature not found" Error

Question

I try to copy a Zip from a Zipinputstream to a Zipoutputstream.

I store the Zip as byte[] in a Oracle database. I use Zipinputstream to decompress the zip (later I want to edit the Zip) and then put it into a Zipoutputstream to get a new byte[] and use this array to download the file later via a ServletOutputStream. When I create a new file - without the Zipinputstream - it works. But when I use the Zipinputstream I get the error.

Here is my code:

        ZipInputStream zipInputStream = new ZipInputStream(new ByteArrayInputStream(fileFromDataBase),
                Charset.forName("UTF-8"));
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        ZipOutputStream zos = new ZipOutputStream(byteArrayOutputStream, Charset.forName("UTF-8"));
        ZipEntry currentEntry;
        byte[] buffer = new byte[8192];
        while ((currentEntry = zipInputStream.getNextEntry()) != null) {
            ZipEntry newEntry = new ZipEntry(currentEntry.getName());
            zos.putNextEntry(newEntry);
            int length;
            while ((length = zipInputStream.read(buffer)) > 0) {
                zos.write(buffer, 0, length);
            }
            zos.closeEntry();                   
        }

        //TO Object to download later the Zipfile from html page
        paketDownloadTO = new PaketDownloadTO();
        paketDownloadTO.setData(byteArrayOutputStream.toByteArray());
        paketDownloadTO.setFileName(fileName);

        zos.finish();
        zipInputStream.close();
        zos.close();

Why? Just copy the bytes. You don't need all this complication. — user207421, Dec 02 '16 at 08:57
Because I later need to edit the zip (put new files into, delete some etc) But if plain copy is not working, then I cant edit it. — Sue, Dec 02 '16 at 09:17

score 8 · Accepted Answer · edited Aug 17 '21 at 02:09

8

My guess is that You should do zos.close() before byteArrayOutputStream.close().

UPDATE:

and move:

paketDownloadTO = new PaketDownloadTO();
paketDownloadTO.setData(byteArrayOutputStream.toByteArray());
paketDownloadTO.setFileName(fileName);

after zos.close();

edited Aug 17 '21 at 02:09

answered Dec 02 '16 at 08:55

Maurice Perry

9,261
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In fact *instead of* `ByteArrayOutputStream.close()` which is redundant if a stream wrapping it has been closed. – user207421 Dec 02 '16 at 08:59
Both do not fix the problem :-( – Sue Dec 02 '16 at 09:21

score 0 · Answer 2 · answered Apr 29 '22 at 15:03

The problem is, calling byteArrayOutputStream.toByteArray() before calling zipInputStream.close()

The ZipInputStream only write the end-of-central-directory when close is called, because before that it does not know if you're going to add new entries or not.

But since byteArrayOutputStream.toByteArray() returns a copy of the byte array at the time you're calling it. It does not contains the end-of-central-directory, which is written to the stream at a later time.

Java: Zipinputstream to Zipoutputstream leads to "end-of-central-directory signature not found" Error

2 Answers2