Korruptes zip File.

[Kopak'rraf]

Hallo,
ich versuche eine zip-Datei zu streamen. Dazu habe ich folgenden Test gemacht. Der Stream funktioniert soweit.

    private final int bufferszize = 1024*16;
    private SessionOutputBuffer wrapOutputStream( final OutputStream outputStream) {
        return new SessionOutputBufferImpl(new HttpTransportMetricsImpl(), bufferszize) {{
            bind(outputStream);
        }};
    }

    static final String AB = "  0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
    static Random rnd = new Random();

    private String randomString( int len ){
        StringBuilder sb = new StringBuilder( len );
        for( int i = 0; i < len; i++ ) {
            sb.append(AB.charAt(rnd.nextInt(AB.length())));
        }
        return sb.toString();
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // Let's send the headers first
        resp.setContentType("application/zip, application/octet-stream");
        resp.setHeader("content-disposition", "attachment;filename=test.zip");
        resp.setHeader("Connection", "keep-alive");
        resp.setHeader("Transfer-Encoding", "chunked");
        resp.flushBuffer();
        final SessionOutputBuffer os = wrapOutputStream(resp.getOutputStream());
        ChunkedOutputStream cos;
        cos = new ChunkedOutputStream(bufferszize,os);

        ZipOutputStream zos = new ZipOutputStream(cos);
        int testfiles;
        for (testfiles=0; testfiles<100; testfiles++){
            String name = "./fileNr." + String.valueOf(testfiles) +".txt";
            ZipEntry ze = new ZipEntry(name);
            ze.setTime(new Date().getTime());
            zos.putNextEntry(ze);
            String br="\n";
            for(int kilobyte=0; kilobyte<100; kilobyte++) {
                String random = randomString(1000)+"\n";
                byte[] bytes = random.toString().getBytes();
                zos.write(bytes,0,bytes.length);
                zos.flush();
                cos.flush();
            }
            zos.closeEntry();
        }
        cos.flush();
        zos.close();
        cos.close();
    }

Allerdings ist die zip-Datei fehlerhaft. Der Fehler macht sich beim öffnen der Datei bemerkbar. Anscheinend stimmen irgendwelche Offsets noch nicht. Was kann das Problem sein?

~/test$ wget -O test.zip --no-check-certificate https://localhost/ziptest
200 OK                                                                                                          
Länge: nicht spezifiziert [application/zip, application/octet-stream]                                                                                           
In »»test.zip«« speichern.                                                                                                                                      

test.zip                                     [    <=>                                                                         ]   7,22M  9,19MB/s    in 0,8s   

»Last-modified«-Kopfzeile ungültig -- Zeitstempel übergangen.
2016-12-23 15:22:52 (9,19 MB/s) - »test.zip« gespeichert [7572534]

~/test$ unzip test.zip
Archive:  test.zip
warning [test.zip]:  8312 extra bytes at beginning or within zipfile
  (attempting to process anyway)
file #1:  bad zipfile offset (local header sig):  8312
  (attempting to re-compensate)
file #1:  bad zipfile offset (local header sig):  8312
file #2:  bad zipfile offset (local header sig):  75574
  (attempting to re-compensate)
file #2:  bad zipfile offset (local header sig):  75574
file #3:  bad zipfile offset (local header sig):  159464