java - Bootstrap File Input JQuery Plugin designed by Krajee (SyntaxError: Unexpected end of input) -

i have problem. used http://plugins.krajee.com/file-input/demo file uploading, right, file uploading on server, on jsp page show message "syntaxerror: unexpected end of input.", although file has been uploaded on server.

my servlet, think problem here (maybe json).

public class uploadimagecommand implements actioncommand {  enum type {      images("/upload/images", ".jpg", ".bmp", ".gif", ".png", ".jpeg"),     videos("/upload/videos", ".avi", ".mpeg", ".mpg", ".mp4", ".mov", ".mkv", ".flv"),     musics("/upload/musics", ".mp3", ".wav");      private string path;     private string[] formats;      type(string path, string... format) {         this.path = path;         this.formats = format;     }      public string[] getformats() {         return formats;     }      public string getpath() {         return path;     } }  private static string parsefileformat(string filename) {     filename = filename.tolowercase();     int dotposition = filename.lastindexof(".");     string format = filename.substring(dotposition, filename.length());     return format; }  private type gettype(string filename) {     string format = parsefileformat(filename);     type[] values = type.values();     (int = 0; < values.length; i++) {         (int j = 0; j < values[i].getformats().length; j++) {             if (values[i] == type.images && values[i].getformats()[j].equals(format)) {                 return type.images;             } else if (values[i] == type.videos && values[i].getformats()[j].equals(format)) {                 return type.videos;             } else if (values[i] == type.musics && values[i].getformats()[j].equals(format)) {                 return type.musics;             }         }     }     return null; }  @override public void execute(httpservletrequest request, httpservletresponse response)         throws servletexception, ioexception {      servletcontext context = request.getsession().getservletcontext();     if (servletfileupload.ismultipartcontent(request)) {         try {             string filename = null;             string filepath;             type type = null;             list<fileitem> multiparts = new servletfileupload(                     new diskfileitemfactory()).parserequest(request);             system.out.println("multipart size: " + multiparts.size());             (fileitem item : multiparts) {                 if (item.getname() == null || item.getname() == "") {                     continue;                 }                 system.out.println("part : " + item.getname());                 if (!item.isformfield()) {                     filename = new file(item.getname()).getname();                     type = gettype(filename);                     filepath = context.getrealpath(type.path);                     if (type != null) {                         securerandom random = new securerandom();                         filename = new biginteger(130, random).tostring(32) +                                 parsefileformat(filename);                         item.write(new file(filepath + file.separator + filename));                         system.out.println("file uploaded successfully");                         // system.out.println("file path: " + context.getrealpath(type.path));                     } else {                         throw new illegalstateexception("wrong file format!");                     }                 }             }             // response.getwriter().print(json.tostring());         } catch (exception e) {             e.printstacktrace();         }     } else {         system.out.println("sorry servlet handles file upload request");     }     response.setcontenttype("application/json"); }  

}

as noticed in http://plugins.krajee.com/file-input#async-send:

you must send valid json response server, else upload process fail. if not encounter error, must @ least send empty json object {} server.