Allow jar app user upload files and save them on user's pc

I have a Spring MVC app which I want to deploy on another users PC via a jar file. How can I allow the user to upload, save and display image files? I am not able to display an image if it's not located in the project folder. Is there a way to solve this?

code for upload:

    public ModelAndView newItemAdd (@RequestParam("file") MultipartFile file, HttpSession session, ModelMap modelMap, @ModelAttribute("itemSaveDto") ItemSaveDto dto) throws IOException {
        if(!Objects.equals(file.getOriginalFilename(), "")){
            String filename=file.getOriginalFilename();
            String newPath = uploadPath+filename;
            file.transferTo(new File(newPath));
            String pic = dbPath+filename;
            dto.setPic(pic);
        }
       if(Objects.equals(file.getOriginalFilename(), "")){
           dto.setPic(defaultPic);
       }
        repo.addItem(dto);
        return new ModelAndView("redirect:/");
    }

html to display images (thymeleaf refers to function which calls URL from database):

 <tr th:each="item: ${items}">
            <td> <img th:src="@{${item.getPic()}}" width="100px" height="100px"/></td>