springboot上传文件或者图片存在后台

1、创建对象FileProperties

@ConfigurationProperties(prefix = "file")
public class FileProperties {

    private String uploadDir;
    public String getUploadDir() {
        return uploadDir;
    }
    public void setUploadDir(String uploadDir) {
        this.uploadDir = uploadDir;
    }

}

2、创建service

/**
 * Created by YINPAN on 2019/10/21
 */
@Service
public class FileService {

    private final Path fileStorageLocation; // 文件在本地存储的地址

    @Autowired
    public FileService(FileProperties fileProperties) {
        this.fileStorageLocation = Paths.get(fileProperties.getUploadDir()).toAbsolutePath().normalize();
        try {
            Files.createDirectories(this.fileStorageLocation);
        } catch (Exception ex) {
            throw new FileException("Could not create the directory where the uploaded files will be stored.", ex);
        }
    }

    /**
     * 存储文件到系统
     *
     * @param file 文件
     * @return 文件名
     */
    public String storeFile(MultipartFile file) {
        // Normalize file name
        String fileName = StringUtils.cleanPath(file.getOriginalFilename());

        try {
            // Check if the file's name contains invalid characters
            if(fileName.contains("..")) {
                throw new FileException("Sorry! Filename contains invalid path sequence " + fileName);
            }

            // Copy file to the target location (Replacing existing file with the same name)
            Path targetLocation = this.fileStorageLocation.resolve(fileName);
            Files.copy(file.getInputStream(), targetLocation, StandardCopyOption.REPLACE_EXISTING);

            return fileName;
        } catch (IOException ex) {
            throw new FileException("Could not store file " + fileName + ". Please try again!", ex);
        }
    }

    /**
     * 加载文件
     * @param fileName 文件名
     * @return 文件
     */
    public Resource loadFileAsResource(String fileName) {
        try {
            Path filePath = this.fileStorageLocation.resolve(fileName).normalize();
            Resource resource = new UrlResource(filePath.toUri());
            if(resource.exists()) {
                return resource;
            } else {
                throw new FileException("File not found " + fileName);
            }
        } catch (MalformedURLException ex) {
            throw new FileException("File not found " + fileName, ex);
        }
    }


}

3、创建Controller

package org.sang.controller;

import org.sang.bean.UploadFileResponse;
import org.sang.service.FileService;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.io.Resource;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.servlet.support.ServletUriComponentsBuilder;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;

/**
 * Created by YINPAN on 2019/10/23
 * 文件上传
 */
@RestController
@RequestMapping("/")
public class FileController {

    private static final Logger logger = LoggerFactory.getLogger(FileController.class);

    @Autowired
    private FileService fileService;

    /**
     * 上传单文件接口
     * @param file
     * @return
     */
    @PostMapping(value="/uploadFile")
    public UploadFileResponse uploadFile(@RequestParam("file") MultipartFile file){

            String fileName = fileService.storeFile(file); //图片名
            String fileDownloadUri = ServletUriComponentsBuilder.fromCurrentContextPath()
                    .path("/downloadFile/")
                    .path(fileName)
                    .toUriString(); //上传图片后的路径


        return new UploadFileResponse(fileName, fileDownloadUri,
                    file.getContentType(), file.getSize());
    }

    /**
     * 上传多文件接口
     * @param file
     * @return
     */
    @PostMapping(value="/uploadFiles")
    public List<UploadFileResponse> uploadMultipleFiles(@RequestParam("files") 
  MultipartFile[] files) {
            return Arrays.stream(files)
                   .map(this::uploadFile)
                   .collect(Collectors.toList());
   }


    @GetMapping("/downloadFile/{fileName:.+}")
    public ResponseEntity<Resource> downloadFile(@PathVariable String fileName, HttpServletRequest request) {
        // Load file as Resource
        Resource resource = fileService.loadFileAsResource(fileName);

        // Try to determine file's content type
        String contentType = null;
        try {
            contentType = request.getServletContext().getMimeType(resource.getFile().getAbsolutePath());
        } catch (IOException ex) {
            logger.info("Could not determine file type.");
        }

        // Fallback to the default content type if type could not be determined
        if(contentType == null) {
            contentType = "application/octet-stream";
        }

        return ResponseEntity.ok()
                .contentType(MediaType.parseMediaType(contentType))
                .header(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"" + resource.getFilename() + "\"")
                .body(resource);
    }
}

4、用Postman测试，上传成功后的数据

访问图片的路径注意 是get请求