Springboot MultipartFile文件上传与下载-编程知识

yml文件配置是否可以上传及上传附件大小

  servlet:multipart:# 允许文件上传enabled: true# 单个文件大小max-file-size: 20MB# 设置总上传的文件大小max-request-size: 50MB

/*** @param files* @param request* @Description 上传文件* @Throws* @Return java.util.List* @Date 2023-08-02 12:11:02* @Author WangKun*/@PostMapping("/upload")public List<JSONObject> upload(@RequestParam("uploadFiles") MultipartFile[] files, HttpServletRequest request) {List<JSONObject> list = new ArrayList<>();for (MultipartFile file : files) {  //循环保存文件JSONObject result = new JSONObject();String msg = "";//判断上传文件格式String fileType = file.getContentType();// 要上传的目标文件存放的绝对路径String path = ClassUtils.getDefaultClassLoader().getResource("").getPath() + "imags";//文件名String fileOldName = file.getOriginalFilename();if (StringUtils.isNotBlank(fileOldName) && StringUtils.isNotEmpty(fileOldName)&& StringUtils.isNotBlank(fileType) && StringUtils.isNotEmpty(fileType)) {//获取文件后缀名String suffixName = fileOldName.substring(fileOldName.lastIndexOf("."));//重新生成文件名String fileNewName = UUID.randomUUID() + suffixName;// 上传if (FileUtils.upload(file, path, fileNewName)) {// 保存数据库信息String id = addAnnex(fileNewName, fileOldName, path, fileType, file.getSize());if (StringUtils.isNotBlank(id) && StringUtils.isNotEmpty(id)) {result.put("fileName", fileNewName);result.put("id", id);msg = "文件上传成功";}} else {msg = "文件上传失败";}}else{msg = "文件名或文件类型为空";}result.put("msg", msg);list.add(result);}return list;}

文件上传到了：\target\classes\imags中

下载：

 /*** @param id* @param response* @Description 文件下载* @Throws* @Return java.util.List<com.alibaba.fastjson2.JSONObject>* @Date 2023-08-02 13:24:41* @Author WangKun*/@GetMapping("/download")public void download(@RequestParam("id") String id, HttpServletRequest request, HttpServletResponse response) {Annex annex = annexService.selectAnnex(id);String fileName = annex.getFileNewName();String charsetCode = String.valueOf(StandardCharsets.UTF_8);try {File file = new File(annex.getFilePath() + File.separator + fileName);//中文乱码解决String type = request.getHeader("User-Agent").toLowerCase();// 字符编码格式if (type.indexOf("firefox") > 0 || type.indexOf("chrome") > 0) {//谷歌或火狐fileName = new String(fileName.getBytes(charsetCode), "iso8859-1");} else {//IEfileName = URLEncoder.encode(fileName, charsetCode);}// 设置响应的头部信息response.setHeader("content-disposition", "attachment;filename=" + fileName);// 设置响应内容的类型response.setContentType(FileUtils.fileContentType(fileName) + "; charset=" + charsetCode);// 设置响应内容的长度response.setContentLength((int) file.length());// 输出FileUtils.outStream(Files.newInputStream(file.toPath()), response.getOutputStream());} catch (Exception e) {log.error("文件下载异常{}", e.getMessage());}}

文件工具类：

/*** @Description 文件上传工具* @Author WangKun* @Date 2023/8/2 10:28* @Version*/
@Slf4j
public class FileUtils {/*** @param file* @param path* @param fileName* @Description 保存文件* @Throws* @Return boolean* @Date 2023-08-02 12:10:39* @Author WangKun*/public static boolean upload(MultipartFile file, String path, String fileName) {String realPath = path + "\\" + fileName;File dest = new File(realPath);//判断文件父目录是否存在if (!dest.getParentFile().exists()) {dest.getParentFile().mkdir();}try {//保存文件file.transferTo(dest);return true;} catch (IllegalStateException | IOException e) {log.error("文件上传{} 异常", e.getMessage(),e);e.printStackTrace();return false;}}/*** @param name* @Description 设置响应头部信息* @Throws* @Return java.lang.String* @Date 2023-08-02 13:39:15* @Author WangKun*/public static String fileContentType(String name) {String result = "";String fileType = name.toLowerCase();if (fileType.endsWith(".png")) {result = "image/png";} else if (fileType.endsWith(".gif")) {result = "image/gif";} else if (fileType.endsWith(".jpg") || fileType.endsWith(".jpeg")) {result = "image/jpeg";} else if (fileType.endsWith(".svg")) {result = "image/svg+xml";} else if (fileType.endsWith(".doc")) {result = "application/msword";} else if (fileType.endsWith(".xls")) {result = "application/x-excel";} else if (fileType.endsWith(".zip")) {result = "application/zip";} else if (fileType.endsWith(".pdf")) {result = "application/pdf";} else if (fileType.endsWith(".mpeg")) { //MP3result = "audio/mpeg";} else if (fileType.endsWith(".mp4")) {result = "video/mp4";} else if (fileType.endsWith(".plain")) {result = "text/plain";} else if (fileType.endsWith(".html")) {result = "text/html";} else if (fileType.endsWith(".json")) {result = "application/json";} else{result = "application/octet-stream";}return result;}/*** @param is* @param os* @Description 文件下载输出* @Throws* @Return void* @Date 2023-08-02 13:40:47* @Author WangKun*/public static void outStream(InputStream is, OutputStream os) {try {byte[] buffer = new byte[10240];int length = -1;while ((length = is.read(buffer)) != -1) {os.write(buffer, 0, length);os.flush();}} catch (Exception e) {log.error("文件下载{} 异常", e.getMessage(),e);} finally {try {os.close();is.close();} catch (IOException e) {log.error("关闭流{} 异常", e.getMessage(),e);e.printStackTrace();}}}}