@RestController
@RequestMapping("/api")
public class FileUploadController {

    @PostMapping("/upload")
    public ResponseEntity<String> uploadFile(@RequestParam("file") MultipartFile file) {
        try {
            if (file.isEmpty()) {
                return ResponseEntity.badRequest().body("请选择要上传的文件");
            }
            
            // 确保目标目录存在
            String uploadDir = "/path/to/upload/directory";
            File dir = new File(uploadDir);
            if (!dir.exists()) {
                dir.mkdirs();
            }
            
            // 保存文件
            String filePath = uploadDir + File.separator + file.getOriginalFilename();
            file.transferTo(new File(filePath));
            
            return ResponseEntity.ok("文件上传成功: " + filePath);
        } catch (IOException e) {
            return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR)
                .body("文件上传失败: " + e.getMessage());
        }
    }
}

# 文件上传大小限制
spring.servlet.multipart.max-file-size=10MB
spring.servlet.multipart.max-request-size=10MB

# 指定临时文件目录（可选）
spring.servlet.multipart.location=/tmp

// 在应用启动时检查目录权限
@SpringBootApplication
public class Application {
    public static void main(String[] args) {
        String uploadDir = "/path/to/upload/directory";
        File dir = new File(uploadDir);
        if (!dir.exists()) {
            boolean created = dir.mkdirs();
            if (!created) {
                throw new RuntimeException("无法创建上传目录: " + uploadDir);
            }
        }
        if (!dir.canWrite()) {
            throw new RuntimeException("上传目录不可写: " + uploadDir);
        }
        
        SpringApplication.run(Application.class, args);
    }
}

@Bean
public MultipartConfigElement multipartConfigElement() {
    MultipartConfigFactory factory = new MultipartConfigFactory();
    factory.setLocation("/tmp/your-app");
    return factory.createMultipartConfig();
}