Spring Boot 实现文件上传、下载功能

Spring Boot 中实现图片上传和下载功能主要涉及到 Spring MVC 的 MultipartFile 类以及文件读写操作。

1. 引入依赖

<dependency>  
    <groupId>org.springframework.boot</groupId>  
    <artifactId>spring-boot-starter-web</artifactId>  
</dependency>

<!-- lombok -->
<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <version>1.18.24</version>
</dependency>

2. 编写配置

spring:
  servlet:
    multipart:
      max-file-size: 10MB # 单个文件最大大小
      max-request-size: 10MB # 请求最大大小

3. 编写配置类

/**
 * 资源配置
 */
@Configuration
public class ResourcesConfig implements WebMvcConfigurer {

    private final static RESOURCE_PREFIX = "/profile";
    
    private final static PROFILE = "/Users/hayden/Downloads";

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry)
    {
        // 本地文件上传路径
        registry.addResourceHandler(RESOURCE_PREFIX + "/**")
                .addResourceLocations("file:" + PROFILE + "/");
    }
}

4. 编写 Controller

@Slf4j
@RestController
public class FileController {

    private final static RESOURCE_PREFIX = "/profile";
    
    private final static PROFILE = "/Users/hayden/Downloads";

    @PostMapping("/upload")
    public String upload(@RequestParam("file") MultipartFile file) {
        if (file.isEmpty()) {
            return R.fail("上传文件不能为空");
        }
        String uploadDir = PROFILE + "/";
        String extension = Objects.requireNonNull(file.getOriginalFilename()).substring(file.getOriginalFilename().lastIndexOf("."));
        String fileName = System.currentTimeMillis() + extension;
        File dest = new File(uploadDir + fileName);

        String url = null;
        HashMap<String, String> map = new HashMap<>();
        try {
            file.transferTo(dest);
            url = serverConfig.getUrl() + RESOURCE_PREFIX + "/" + fileName;
            map.put("name", fileName);
            map.put("url", url);
        } catch (IOException e) {
            log.error("上传文件失败", e);
            return R.fail("上传文件失败", e.getMessage());
        }
        log.info("上传文件成功，文件：" + map);
        return R.ok(map);
    }
    
    @GetMapping("/download")
    public void download(@RequestParam("fileName") String fileName, HttpServletResponse response) {
        if (fileName != null) {
            File file = new File(PROFILE + "/" + fileName);
            if (file.exists()) {
                response.setContentType("application/force-download");
                response.addHeader("Content-Disposition", "attachment;fileName=" + fileName);
                byte[] buffer = new byte[1024];
                FileInputStream fis = null;
                BufferedInputStream bis = null;
                try {
                    fis = new FileInputStream(file);
                    bis = new BufferedInputStream(fis);
                    OutputStream os = response.getOutputStream();
                    int i = bis.read(buffer);
                    while (i != -1) {
                        os.write(buffer, 0, i);
                        i = bis.read(buffer);
                    }
                    log.info("下载文件成功，文件：" + fileName);
                } catch (Exception e) {
                    log.error("下载文件失败", e);
                } finally {
                    if (bis != null) {
                        try {
                            bis.close();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                    if (fis != null) {
                        try {
                            fis.close();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                }
            }
        }
    }
}