给出springboot文件上传下载代码

Spring Boot 提供了很好的支持来处理文件上传和下载。下面是一个简单的示例代码：

1. 文件上传

@RestController
public class FileUploadController {

    @Autowired
    private StorageService storageService;

    @PostMapping("/upload")
    public ResponseEntity<String> handleFileUpload(@RequestParam("file") MultipartFile file) {
        String message = "";
        try {
            storageService.store(file);
            message = "You successfully uploaded " + file.getOriginalFilename() + "!";
            return ResponseEntity.status(HttpStatus.OK).body(message);
        } catch (Exception e) {
            message = "FAIL to upload " + file.getOriginalFilename() + "!";
            return ResponseEntity.status(HttpStatus.EXPECTATION_FAILED).body(message);
        }
    }
}

2. 文件下载

@RestController
public class FileDownloadController {

    @Autowired
    private StorageService storageService;

    @GetMapping("/download/{fileName:.+}")
    public ResponseEntity<Resource> downloadFile(@PathVariable String fileName, HttpServletRequest request) {
        Resource resource = storageService.loadFileAsResource(fileName);
        String contentType = null;
        try {
            contentType = request.getServletContext().getMimeType(resource.getFile().getAbsolutePath());
        } catch (IOException ex) {
            ex.printStackTrace();
        }
        if (contentType == null) {
            contentType = "application/octet-stream";
        }
        return ResponseEntity.ok().contentType(MediaType.parseMediaType(contentType))
                .header(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"" + resource.getFilename() + "\"")
                .body(resource);
    }
}

其中，`StorageService` 是一个自定义的服务类，用于处理文件存储和加载。在这里不展开具体实现，可以自行搜索相关资料。