SpringBoot怎么实现文件存储和文件下载

SpringBoot可以通过以下方法实现文件存储和文件下载：

1. 文件存储

- 使用SpringBoot内置的文件上传组件MultipartFile来接收文件并保存到指定目录中。

示例代码：

@PostMapping("/upload")
public String uploadFile(@RequestParam("file") MultipartFile file) {
    try {
        String fileName = StringUtils.cleanPath(file.getOriginalFilename());
        Path path = Paths.get(uploadDir + fileName);
        Files.copy(file.getInputStream(), path, StandardCopyOption.REPLACE_EXISTING);
        return "File uploaded successfully!";
    } catch (IOException e) {
        throw new RuntimeException("Could not store the file. Error: " + e.getMessage());
    }
}

- 使用第三方存储服务，如阿里云OSS、七牛云等。

示例代码：

@Autowired
private OSSClient ossClient;

@PostMapping("/upload")
public String uploadFile(@RequestParam("file") MultipartFile file) {
    try {
        String fileName = StringUtils.cleanPath(file.getOriginalFilename());
        InputStream inputStream = file.getInputStream();
        ObjectMetadata objectMetadata = new ObjectMetadata();
        objectMetadata.setContentLength(file.getSize());
        ossClient.putObject(bucketName, fileName, inputStream, objectMetadata);
        return "File uploaded successfully!";
    } catch (IOException e) {
        throw new RuntimeException("Could not store the file. Error: " + e.getMessage());
    }
}

2. 文件下载

- 使用SpringBoot内置的响应实体类ResponseEntity，将文件以流的形式返回给客户端。

示例代码：

@GetMapping("/download")
public ResponseEntity<Resource> downloadFile(@RequestParam("fileName") String fileName) {
    try {
        Path path = Paths.get(uploadDir + fileName);
        Resource resource = new UrlResource(path.toUri());
        return ResponseEntity.ok()
                .contentType(MediaType.parseMediaType("application/octet-stream"))
                .header(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"" + resource.getFilename() + "\"")
                .body(resource);
    } catch (MalformedURLException e) {
        throw new RuntimeException("Could not download the file. Error: " + e.getMessage());
    }
}

- 使用第三方存储服务的下载接口，如阿里云OSS、七牛云等。

示例代码：

@Autowired
private OSSClient ossClient;

@GetMapping("/download")
public void downloadFile(@RequestParam("fileName") String fileName, HttpServletResponse response) {
    try {
        OSSObject ossObject = ossClient.getObject(bucketName, fileName);
        InputStream inputStream = ossObject.getObjectContent();
        response.setContentType("application/octet-stream");
        response.setHeader(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"" + fileName + "\"");
        IOUtils.copy(inputStream, response.getOutputStream());
        response.flushBuffer();
    } catch (IOException e) {
        throw new RuntimeException("Could not download the file. Error: " + e.getMessage());
    }
}