Java：使用唯一名称重命名MultiPartFile并将其存储到文件夹并将URL保存到数据库

我有一个基于Spring Boot的后端，一个基于Angular 5的前端。通过Angular接收MultiPartFile之后，我想使用唯一的名称（表的ID）重命名此文件并将其存储到文件夹中，然后将该文件的URL放入到数据库PostgreSQL。请帮助我，我测试了很多方法，但均未取得任何好的结果。我试图将MultiPartFile转换为File，但是我不知道该怎么做。请帮我

这是包含处理MultiPartFile的方法的类：

package smart.syndic.metier;

import java.net.MalformedURLException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardCopyOption;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.io.Resource;
import org.springframework.core.io.UrlResource;
import org.springframework.stereotype.Service;
import org.springframework.util.FileSystemUtils;
import org.springframework.web.multipart.MultipartFile;

@Service
public class StorageService 
{
Logger logger = LoggerFactory.getLogger(this.getClass().getName());
private final Path rootLocation = Paths.get("fichiers/prestataires");

public void store(MultipartFile file) {
    try {

        Files.copy(file.getInputStream(), 
this.rootLocation.resolve(file.getOriginalFilename()), 
StandardCopyOption.REPLACE_EXISTING);
    } catch (Exception e) {
        throw new RuntimeException("FAIL!");
    }
 }

public Resource loadFile(String filename) {
    try {
        Path file = rootLocation.resolve(filename);
        Resource resource = new UrlResource(file.toUri());
        if (resource.exists() || resource.isReadable()) {
            return resource;
        } else {
            throw new RuntimeException("FAIL!");
        }
    } catch (MalformedURLException e) {
        throw new RuntimeException("FAIL!");
    }
 }

public void deleteAll() {
    FileSystemUtils.deleteRecursively(rootLocation.toFile());
 }
}

这是RestController：

package smart.syndic.web;

import java.util.ArrayList;
 import java.util.List;
 import java.util.stream.Collectors;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.io.Resource;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.http.HttpHeaders;
import org.springframework.http.ResponseEntity;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.CrossOrigin;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;


import  org.springframework.web.servlet.mvc.method.annotation.
MvcUriComponentsBuilder;
import smart.syndic.dao.PrestatairesRepository;
import smart.syndic.dao.PrestatairesTypesRepository;
import smart.syndic.entities.Prestataires;
import smart.syndic.metier.StorageService;

@RestController
@CrossOrigin("*")
public class PrestatairesRestController 
{
@Autowired
private PrestatairesRepository repository;

@Autowired
private PrestatairesTypesRepository repository2;

@Autowired
private StorageService storageService;

private List<String> files = new ArrayList<String>();

@RequestMapping(value="/prestataires/{id}", 
        method=RequestMethod.GET)
public Prestataires getVilles(@PathVariable Long id)
{
    return repository.findOne(id);
}

@RequestMapping(value="/prestataires", 
        method=RequestMethod.POST)
public Prestataires addVilles(Prestataires p,
        @RequestParam("multipartFile") MultipartFile file)
{
    try{
        storageService.store(file);
        files.add(file.getOriginalFilename());
        p.setPhoto("fichiers/prestataires/"+file.getOriginalFilename());

    }catch(Exception e){
        e.printStackTrace();
    }


 p.setPrestatairesTypes(repository2.findOne(p.getPrestatairesTypes()
 .getId()));

    return repository.save(p);              
}

}

这是Entity Prestataires：

package smart.syndic.entities;

import java.io.Serializable;
import java.util.Collection;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;

@Entity
public class Prestataires implements Serializable 
{
@Id @GeneratedValue
private Long id;
private String nom;
private String email;
private String tele;
private String fax;
private String rib;
private String adresse;
private String taches;
private String photo;

//-------------------Constructors--------------------
//-------------------Getters and Setters--------------------


@ManyToOne
@JoinColumn(name="ID_PRESTATAIRES_TYPES")
private PrestatairesTypes prestatairesTypes;
}