how to upload file into googlecloud through java -

i want upload file bucket in google cloud storage api. when run servelet class deployed , shows output in browser " see here file content, have uploaded on storage.. file uploading done" .

but problem servelet class not establish connection google cloud storage.and file not uploaded bucket.once check

the code , give suggestion how connect bucket source code.

 public class testcloudstorageservlet extends httpservlet{   private static final long serialversionuid = 1l;  private storageservice storage = new storageservice();  private static final int buffer_size = 1024 * 1024;  private static final logger log = logger.getlogger(testcloudstorageservlet.class.getname());   @override     public void dopost(httpservletrequest req, httpservletresponse resp) throws ioexception {    log.info(this.getservletinfo()+" servlets called....");      resp.setcontenttype("text/plain");     resp.getwriter().println("now see here file content, have uploaded on    storage..");    servletfileupload upload = new servletfileupload();      system.out.println(upload);     fileitemiterator iter;    try {     iter = upload.getitemiterator(req);      while (iter.hasnext()) {    fileitemstream item = iter.next();    string filename = item.getname();    string mime = item.getcontenttype();     storage.init(filename, mime);    inputstream = item.openstream();     byte[] b = new byte[buffer_size];    int readbytes = is.read(b, 0, buffer_size);    while (readbytes != -1) {        storage.storefile(b, readbytes);        readbytes = is.read(b, 0, readbytes);    }     is.close();    storage.destroy();      resp.getwriter().println("file uploading done");       //resp.getwriter().println("read:" + storage.readtextfileonly(filename));                       log.info(this.getservletname()+" ended....");                }      }         catch (fileuploadexception e) {            system.out.println("fileuploadexception::"+e.getmessage());          log.severe(this.getservletname()+":fileuploadexception::"+e.getmessage());       e.printstacktrace();        } catch (exception e) {     log.severe(this.getservletname()+":exception::"+e.getmessage());          system.out.println("exception::"+e.getmessage());      e.printstacktrace();      }        } 

my storageservice class uploading file.

       public class storageservice {           public static final string bucket_name = "mybucketname";            private filewritechannel writechannel = null;             fileservice fileservice = fileservicefactory.getfileservice();         private outputstream os = null;         private static final logger log =            logger.getlogger(storageservice.class.getname());         public void init(string filename, string mime) throws exception {       system.out.println("storage service:init() method:  file name:"+filename+"  ,                mime:"+mime);      log.info("storage service:init() method:  file name:"+filename+" , mime:"+mime);         log.info("test..");     gsfileoptionsbuilder builder = new gsfileoptionsbuilder()         .setacl("public_read")         .setbucket(bucket_name)         .setkey(filename)         .setmimetype(mime);    log.info("test..");  appenginefile writablefile = fileservice.createnewgsfile(builder.build());  boolean lock = true;  writechannel = fileservice.openwritechannel(writablefile, lock);     os = channels.newoutputstream(writechannel);       }          public void storefile(byte[] b, int readsize) throws exception {       os.write(b, 0, readsize);         os.flush();      }         public void destroy() throws exception {       log.info("storage service: destroy() method");       os.close();     writechannel.closefinally();        }         }