用户springboot写一个文件上传的代码

好的，这里是一个简单的Spring Boot文件上传的代码：

@RestController
public class FileUploadController {

    @PostMapping("/upload")
    public ResponseEntity<String> uploadFile(@RequestParam("file") MultipartFile file) {

        // Check if file is empty
        if (file.isEmpty()) {
            return new ResponseEntity<>("Please select a file to upload", HttpStatus.BAD_REQUEST);
        }

        // Get the file name and extension
        String fileName = StringUtils.cleanPath(file.getOriginalFilename());
        String fileExtension = fileName.substring(fileName.lastIndexOf("."));

        // Save the file to the local file system
        try {
            String savePath = "C:/uploads/";
            File uploadDir = new File(savePath);

            if (!uploadDir.exists()) {
                uploadDir.mkdir();
            }

            String uploadFilePath = savePath + fileName;
            File dest = new File(uploadFilePath);
            file.transferTo(dest);
        } catch (IOException e) {
            return new ResponseEntity<>("Failed to upload file", HttpStatus.INTERNAL_SERVER_ERROR);
        }

        // Return success
        return ResponseEntity.ok("File uploaded successfully");
    }
}

这个控制器基于RESTful架构，使用了`@PostMapping`注释匹配POST请求（在这个例子中，是`/upload`）。它所做的就是接收一个文件（`@RequestParam`注释指定了这个参数的名字为`file`），检查文件是否为空，保存这个文件到本地文件系统然后返回一个成功信息。

如果上传成功，响应将会是以下内容：

{
    "status": 200,
    "message": "File uploaded successfully"
}

当发生错误时（比如说，上传一个空文件），响应将会是以下内容：

{
    "status": 400,
    "message": "Please select a file to upload"
}