Java中的多种文件上传方式总结

请求类型

单文件上传

    //上传单个文件
  @ResponseBody
  @RequestMapping(value = "uploadfile", produces = "multipart/form-data;charset=UTF-8")
  public String uploadfiles(HttpServletRequest request){
      CommonsMultipartResolver multipartResolver = new CommonsMultipartResolver(request.getSession().getServletContext());
      if (multipartResolver.isMultipart(request)) {
          DefaultMultipartHttpServletRequest multipartRequest = (DefaultMultipartHttpServletRequest) request;
          MultipartFile multipartFile = multipartRequest.getFile("file");
          if (multipartFile == null) {
              System.out.println("multipartFile == null");
          }
          String filename = multipartRequest.getFile("file").getOriginalFilename();
          String tmpFile = request.getSession().getServletContext().getRealPath("/") + UUID.randomUUID().toString().replace("-", "") + ".apk";
          File targetFile = new File(tmpFile);
          AppEntity appEntity = new AppEntity();
          if (null != multipartFile) {
              //保存文件
              try {
                  multipartFile.transferTo(targetFile);
              } catch (IllegalStateException e) {
                  logger.error("multipartFile.transferTo, IllegalStateException", e);
              } catch (IOException e) {
                  logger.error("multipartFile.transferTo, IOException", e);
              }
          }
      }
      return "";
  }

多文件上传

多文件单字段上传

    @ResponseBody
  @RequestMapping(value = "uploadfiles", produces = "multipart/form-data;charset=UTF-8")
  public String uploadfile(MultipartHttpServletRequest request){
      CommonsMultipartResolver multipartResolver = new CommonsMultipartResolver(request.getSession().getServletContext());
      if (multipartResolver.isMultipart(request)) {
          //上传多个文件，一个字段中包含多个文件
          String projectPath = request.getSession().getServletContext().getRealPath("/");
          MultiValueMap<String, MultipartFile> multiFileMap = request.getMultiFileMap();
          List<MultipartFile> fileSet = new LinkedList<>();
          for(Map.Entry<String, List<MultipartFile>> temp : multiFileMap.entrySet()){
              fileSet = temp.getValue();
          }
          for(MultipartFile temp : fileSet){
              File file2 = new File(projectPath+temp.getOriginalFilename());
              try {
                  temp.transferTo(file2);
              } catch (IOException e) {
                  e.printStackTrace();
              }
          }
      }
      return "";
  }

多文件多字段上传

    @ResponseBody
  @RequestMapping(value = "uploadfiles", produces = "multipart/form-data;charset=UTF-8")
  public String uploadfile(MultipartHttpServletRequest request){
      CommonsMultipartResolver multipartResolver = new CommonsMultipartResolver(request.getSession().getServletContext());
      if (multipartResolver.isMultipart(request)) {
          //上传多个文件，每个字段一个文件
          Iterator<String> fileNames = request.getFileNames();
          while (fileNames.hasNext()){
              // 取得上传文件
              String uploadName = fileNames.next();
              MultipartFile file = request.getFile(uploadName);
              if (file != null) {
                  String projectPath = request.getSession().getServletContext().getRealPath("/");
                  String originalFilename = file.getOriginalFilename();
                  String tmpFile = projectPath + System.currentTimeMillis() + "_" + originalFilename;
                  File targetFile = new File(tmpFile);
                  try {
                      file.transferTo(targetFile);
                  } catch (IOException e) {
                      e.printStackTrace();
                  }
              }
          }
      }
      return "";
  }

如果上面方法不行,看下面

@PostMapping(value = "test", produces = "multipart/form-data;charset=UTF-8")
public void UploadFiles(HttpServletRequest request) throws IOException {
  //如果请求中包含文件
  if(ServletFileUpload.isMultipartContent(request)){
      // 创建一个通用的多部分解析器
      MultipartHttpServletRequest multipartRequest = (MultipartHttpServletRequest) request;
      List<MultipartFile> files = multipartRequest.getFiles("file");
      File targetFile;
      for (MultipartFile file : files){
          //保存文件到本地
          String projectPath = request.getSession().getServletContext().getRealPath("/");
          projectPath = projectPath + System.currentTimeMillis() + "_" + new Random().nextInt(100);
          File dir = new File(projectPath);
          if (!dir.exists()){
              dir.mkdir();
          }
          String originalFilename = file.getOriginalFilename();
          String tmpFile = projectPath + File.separator + originalFilename;
          targetFile = new File(tmpFile);
          file.transferTo(targetFile);
          //将文件保存到本地并记录信息
          //...
      }
  }
}

还有一种方法，函数入参直接接受文件

例如：

//单文件
public String UploadFiles(@RequestParam("file") MultipartFile file){
}
//多文件
public String UploadFiles(@RequestParam("file") List<MultipartFile> files){
}

以上为个人经验，希望能给大家一个参考，也希望大家多多支持服务器之家。

原文链接：https://enjoy-day.blog.csdn.net/article/details/108073772