Getting a java.util.zip.ZipException when trying to create a ZipFile in JAVA?

Question

I am getting this error:

java.util.zip.ZipException: invalid CEN header (bad signature)

and I am not quite sure what is the problem, when I search google for CEN header nothing useful is found.

Any help is appreciated, thanks.

Here is the code and it fails on the last line:

ZipFile resourceZip = null;
if (pir.getSource().endsWith("Resources.zip")) 
{
    File temp = new File( "C:\\Users\\nbonnet\\Desktop\\new\\Resources1.zip");
    byte[] bytesFromClob = ClobHelper.bytesFromClob(pir.getContents(),"latin1");
    FileOutputStream out = new FileOutputStream(temp);
    out.write(bytesFromClob);
    out.flush();
    out.close();
    resourceZip = new ZipFile(temp);  // <-- Code fails here
}

Did you see this page helpdesk.objects.com.au/java/invalid-cen-header which states that the error may be caused by a zip file containing an entry larger than 4GB in size. — Bobulous
– Bobulous, Commented Aug 31, 2012 at 18:19
Also this page bugs.sun.com/bugdatabase/view_bug.do?bug_id=6432010 which suggests that the compression method used to create the zip is not supported by the JDK. — Bobulous
– Bobulous, Commented Aug 31, 2012 at 18:20
I added the code I am running. Also I am 100% sure the file is less than 4GB. As far as the compression ... is there a workaround? Can i tell it to do some other compression? — nbonbon
– nbonbon, Commented Aug 31, 2012 at 18:29
Why are you storing binary data in a CLOB? I would suggest that you compare the data that you're reading from the database with the data that you're putting into it. I'll bet they're different. — kdgregory
– kdgregory, Commented Aug 31, 2012 at 18:35

Keith Randall · Accepted Answer · 2012-08-31 18:33:48Z

4

You're writing the file as a regular (non-ZIP) file and then trying to read it back as a ZIP file. That's not going to work. You need to write it with a ZipOutputStream.

Check out this example or this one.

answered Aug 31, 2012 at 18:33

Keith Randall

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7 Comments

Hot Licks Over a year ago

Right. There's nothing in the code above that would create a zip file.

nbonbon Over a year ago

I have tried that but then I get this error: java.util.zip.ZipException: no current ZIP entry But the whole reason I am writing it out to a zip is because I need to see the entries. I believe it throws this because I am not using out.putNextEntry()..

kdgregory Over a year ago

@Keith - that's one interpretation. Another is that the data in the database is in ZIP format. Of course, as I noted in my comment, it's strange that the data is coming from a CLOB rather than a BLOB.

Keith Randall Over a year ago

@kdgregory: true, that's another possibility. If so, the header of the file is getting corrupted somehow (character set conversion?).

kdgregory Over a year ago

Possibly character set conversion, or perhaps the CLOB is rejecting any 0 bytes. I figured I gave the OP enough of a hint ... I suspect there are worse problems to come.

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