Zipper des fichiers

Bonjour,
je dois recuperer des fichiers sur un serveur, les zipper, puis les envoyer sur la sortie en telechargement (java web pour info).

J'ai un code qui compile mais le fichier semble etre corrompu. Il fait la taille du premier fichier que je lui passe seulement et ni windows ni 7zip ne peuvent l'ouvrir.

Voici mon code, en esperant que quelqu'un pourra m'aider.
[code]
// These are the files to include in the ZIP file
List<String> filenames = down.getFilenames();
List<String> urls = down.getUrls();
byte data[] = new byte[1024];

try {
HttpClient client = new HttpClient();
// set default retry handler

client.getParams().setParameter(HttpMethodParams.RETRY_HANDLER,
new DefaultHttpMethodRetryHandler());

// Create the ZIP file
String outFilename = "outfile.zip";

FileOutputStream dest = new FileOutputStream(outFilename);
BufferedOutputStream buff = new BufferedOutputStream(dest);
ZipOutputStream out = new ZipOutputStream(buff);

out.setMethod(ZipOutputStream.DEFLATED);
out.setLevel(9);

// Compress the files
for (int i=0; i<filenames.size(); i++) {

//make an HTTP GET
HttpMethod method = new GetMethod(urls.get(i));
client.executeMethod(method);

InputStream is = method.getResponseBodyAsStream();

BufferedInputStream buffi=new BufferedInputStream(is,1024);

ZipEntry ze=new ZipEntry(filenames.get(i));

// Add ZIP entry to output stream.
out.putNextEntry(ze);

int count;
while((count = buffi.read(data, 0, 1024)) != -1) {
out.write(data, 0, count);
}

// Complete the entry
out.closeEntry();

buffi.close();

}
out.finish();
out.close();
String zip=buff.toString();

response.setContentType( "application/zip" );
response.setHeader( "Content-Disposition", "attachment; filename=\""+outFilename+"\"" );

ServletOutputStream op = response.getOutputStream();
op.println(zip);
op.flush();
/code