把字符串数据打包成压缩包并返回浏览器提示下载

byte[] buf = new byte[8192];
        int len;
        for (String filename :filenameToData.keySet()
             ) {
            ZipEntry ze = new ZipEntry(filename + ".txt");
            zos.putNextEntry(ze);
            if(null != filenameToData.get(filename))
            {
                ByteArrayInputStream bis = new ByteArrayInputStream(modelDataMap.get(filename).getBytes());
                while ( ( len = bis.read( buf ) ) > 0 ) {
                    zos.write( buf, 0, len );
                }
            }
            zos.closeEntry();
        }
        
        response.setHeader("Content-Disposition","attachment; filename=\"" + zipname+".zip" + "\"");
        response.setContentType("application/zip");

        os.write(bos.toByteArray());
        bos.close();
        zos.close();