SpringBoot 文件上传下载

文件上传

配置

# 文件上传校验
# 开启上传和下载
spring.servlet.multipart.enabled=true
# 最大的文件大小
spring.servlet.multipart.max-file-size=50KB
# 单次最大请求大小
spring.servlet.multipart.max-request-size=50KB

单个(批量)上传

@RestController
public class FileUploadController {
   
	// 用于根据时间区分目录
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy/MM/dd");

    @PostMapping("/upload")
    public String upload(MultipartFile uploadFile, HttpServletRequest req){
   
    	// 上传文件路径
        String realPath = req.getSession().getServletContext().getRealPath("/uploadFile/");
        String format = sdf.format(new Date());
        File folder = new File(realPath + format);
        // 判断文件夹是否存在
        if(!folder.isDirectory()){
   
            folder.mkdirs();
        }
        // 获取原始名字
        String oldName = uploadFile.getOriginalFilename();
        String newName = UUID.randomUUID().toString() + oldName.substring(oldName.lastIndexOf("."), oldName.length());
        try{
   
            uploadFile.transferTo(new File(folder, newName));
            String filePath = req.getScheme() + "://" + req.getServerName() + ":" + req.getServerPort() + "/uploadFile/" + format + newName;
            return filePath;
        }catch (IOException e){
   
            e.printStackTrace();
        }
        return "上传失败";
    }

	// 批量即在单个的基础上增加遍历
    @PostMapping("/uploads")
    public String uploads(MultipartFile[] uploadFiles, HttpServletRequest req){
   
        ArrayList<String> pathList = new ArrayList<>();
        for(MultipartFile uploadFile : uploadFiles){
   
            String realPath = req.getSession().getServletContext().getRealPath("/uploadFile/");
            String format = sdf.format(new Date());
            File folder = new File(realPath + format);
            if(!folder.isDirectory()){
   
                folder.mkdirs();
            }
            String oldName = uploadFile.getOriginalFilename();
            String newName = UUID.randomUUID().toString() + oldName.substring(oldName.lastIndexOf("."), oldName.length());
            try{
   
            	// 将上传文件保存到一个目标文件中
                uploadFile.transferTo(new File(folder, newName));
                String filePath = req.getScheme() + "://" + req.getServerName() + ":" + req.getServerPort() + "/uploadFile/" + format + newName;
                pathList.add(filePath);
            }catch (IOException e){
   
                e.printStackTrace();
            }
        }
        return pathList.toString();
        //return "上传失败";
    }
}

bytell getBytes()。获取文件数据
String getContentType()。获取文件 MIME 类型，如 image/ipeg 等.
InputStream getlnputStream()。获取文件流
String getName()。获取表单中文件组件的名字。
String getOriginalFilename()。获取上传文件的原名
long getSize()。获取文件的字节大小，单位为 byte。
boolean isEmpty()。是否有上传的文件
void transferTo(File dest)。将上传文件保存到一个目标文件中。

前台

 单个上传
<form action="/upload" method="post" enctype="multipart/form-data">
    <input type="file" name="uploadFile" value="请选择文件"/>
    <input type="submit" value="上传">
</form>
多个上传
<form action="/uploads" method="post" enctype="multipart/form-data">
    <input type="file" name="uploadFiles" value="请选择文件" multiple/>
    <input type="submit" value="上传">
</form>

文件下载

@GetMapping("/download")
    public ResponseEntity<InputStreamResource> downloadFile(HttpServletRequest req, @RequestParam("filename") String filename) throws IOException{
   
        // 下载文件路径
        String path = req.getSession().getServletContext().getRealPath("/uploadFile/");
        // File.separator /
        InputStream is = new FileInputStream(path + File.separator + filename);
        InputStreamResource resource = new InputStreamResource(is);
        HttpHeaders headers = new HttpHeaders();
        // 通知浏览器以attachment（下载方式）打开图片
        headers.add("Content-Disposition", "attachment; filename=\"" + filename + "\"");
        headers.add("Cache-Control", "no-cache, no-store, must-revalidate");
        headers.add("Pragma", "no-cache");
        headers.add("Expires", "0");

        return ResponseEntity.ok()
                .headers(headers)
                .contentLength(is.available())
                // 二进制流数据（最常见的文件下载）
                .contentType(MediaType.parseMediaType("application/octet-stream"))
                .body(resource);
    }