<form th:action="@{/employee/upload2}" method="post" enctype="multipart/form-data">
    姓名: <input type="text" name="lastName">
    <br>
    年龄: <input type="text" name="age">
    <br>
    邮箱: <input type="email" name="email">
    <br>
    文件: <input type="file" name="file">
    <br>
    desc: <input type="text" name="desc">
    <input type="submit" value="提交">
</form>
<hr>
<form th:action="@{/employee/multiup2}" method="post" enctype="multipart/form-data">
    文件<input type="file" name="file">
    <br>
    文件<input type="file" name="file">
    <br>
    文件<input type="file" name="file">
    <br>
    <input type="submit" value="提交">
</form>
<hr>
<!--常量参数要加引号-->
<a th:href="@{/employee/down(filename=‘图片.PNG‘)}">下载图片</a>
<br>
<a th:href="@{/employee/down(filename=‘2.PNG‘)}">下载2</a>
</body>

@ResponseBody
    @RequestMapping("/get/{id}")
    public Employee getRest(@PathVariable("id") Integer id, HttpServletRequest request) {
        //D:\workspace_for_idea\springboot\springboot-test\src\main\webapp
        System.out.println(request.getServletContext().getRealPath("/"));
        //D:\workspace_for_idea\springboot\springboot-test\.
        System.out.println(new File(".").getAbsolutePath());
        //D:\
        System.out.println(new File("/").getAbsolutePath());
        //D:\workspace_for_idea\springboot\springboot-upload-download\
        String path = System.getProperty("user.dir");
        return employeeService.getById(id);
    }

 /*
    单独文件上传
     */
    @ResponseBody
    @PostMapping("/upload1")
    public String upload1(String desc,
                          Employee employee,
                          @RequestParam("file") MultipartFile multipartFile) throws IOException {
        //上传的文件不能为空
        if (multipartFile.isEmpty()) {
            return "上传失败, 请选择文件";
        }
        //springboot对封装的对象自动做了处理,能直接拿到值,但是springMvc不能
        System.out.println(employee);
        System.out.println(desc);
        //D:\workspace_for_idea\springboot\springboot-upload-download        //获取当前项目所在位置
        String filename = multipartFile.getOriginalFilename();
        System.out.println("文件大小===>" + multipartFile.getSize());
        System.out.println("上传文件类型===>" + multipartFile.getContentType());
        //获取根路径
        String path = System.getProperty("user.dir");
        File file = new File(path + "/files/" + filename);
        //判断父目录是否存在
        if (!file.getParentFile().exists()) {
            //新建文件
            file.getParentFile().mkdir();
        }
        String absolutePath = file.getAbsolutePath();
        System.out.println("文件路径===>" + absolutePath);
        multipartFile.transferTo(file);
        return "上传成功upload1";
    }
?
    @ResponseBody
    @PostMapping("/upload2")
    public String upload2(@RequestParam("file") MultipartFile multipartFile) {
        if (multipartFile.isEmpty()) {
            return "上传失败, 请选择文件";
        }
        String filename = multipartFile.getOriginalFilename();
        System.out.println("filename===>" + filename);
        System.out.println("文件大小===>" + multipartFile.getSize());
        System.out.println("contentType===>" + multipartFile.getContentType());
        String path = System.getProperty("user.dir");
        //两种方式获取文件后缀名,正则中. 用\\.表示
        System.out.println(filename.split("\\.")[1]);
        String suffix = filename.substring(filename.indexOf(".") + 1);
        System.out.println("文件后缀名" + suffix);
        //忽略大小写判断文件格式
        if (!(suffix.equalsIgnoreCase("png") || suffix.equalsIgnoreCase("jpg"))) {
            return "文件格式错误";
        }
        File file = new File(path + "/files/" + filename);
        if (!file.getParentFile().exists()) {
            file.getParentFile().mkdir();
        }
        String absolutePath = file.getAbsolutePath();
        System.out.println("文件路径===>" + absolutePath);
        try {
            multipartFile.transferTo(file);
            return "上传成功";
        } catch (IOException e) {
            e.printStackTrace();
        }
        return "失败upload2";
    }

  /*
    多文件上传
    也可以采用  @RequestParam("file") Multipart[] 来作为参数
     */
    @ResponseBody
    @PostMapping("/multiup1")
    public String multiUpLoad(HttpServletRequest request) {
        //getFile中的name对应前端的name
        List<MultipartFile> files = ((MultipartHttpServletRequest) request).getFiles("file");
        for (int i = 0; i < files.size(); i++) {
            MultipartFile file = files.get(i);
            //必须上传文件
            if (file.isEmpty()) {
                log.info("上传第" + (i + 1) + "个文件失败");
                return "上传第" + (i + 1) + "个文件失败";
            }
            String filename = file.getOriginalFilename();
            String path = request.getServletContext().getRealPath("/files");
            File filePath = new File(path + "/" + filename);
            if (!filePath.getParentFile().exists()) {
                filePath.getParentFile().mkdir();
            }
            try {
                log.info("上传第" + (i + 1) + "个文件成功");
                file.transferTo(filePath);
            } catch (IOException e) {
                log.info("上传第" + (i + 1) + "个文件失败");
                e.printStackTrace();
                return "上传第" + (i + 1) + "个文件失败";
            }
        }
        return "上传成功multiup1";
    }
?
    /*
    stream多文件上传
     */
    @ResponseBody
    @PostMapping("/multiup2")
    public String multiUpload(@RequestParam("file") MultipartFile[] files) {
        //可以通过stream流操作,流操作一定要有终止操作才会正真的执行
        Long collect = Arrays.stream(files).map(this::upload2).collect(Collectors.counting());
        log.info(collect + "个文件上传成功");
        return "上传成功multiup2";
    }
?

 /*
    下载文件
     */
    @GetMapping("/down")
    public void download(HttpServletRequest request,
                         HttpServletResponse response,
                         @RequestParam String filename) throws IOException {
        String header = request.getHeader("User-Agent");
//        String path="files"+File.separator+filename;
        String path = Paths.get("files", filename).toString();
        System.out.println("filename==========>" + filename);
        //设置消息头
        response.setContentType("application/force-download");//强制下载不打开
        //消息头,固定格式, filename这里是文件的名字
        response.addHeader("Content-Disposition", "attachment;filename=" + URLEncoder.encode(filename, "utf-8"));
        try (FileInputStream fis = new FileInputStream(path);
             BufferedInputStream bis = new BufferedInputStream(fis);
             ServletOutputStream responseOutputStream = response.getOutputStream()) {
            byte[] buffer = new byte[1024];
            int len = -1;
            while ((len = bis.read(buffer)) != -1) {
                responseOutputStream.write(buffer, 0, len);
            }
        }
    }