方式一

情況1：

	@PostMapping("/download1")public ResponseEntity<byte[]> download1() throws Exception {// 下載文件目錄位置FileInputStream fis = new FileInputStream("C:\\Users\\wsd\\Pictures\\susu.jpg");// 一次讀取bytes.length 個字節并將讀到的字節放入bytes數組中byte[] bytes = new byte[fis.available()];fis.read(bytes);fis.close();HttpHeaders httpHeaders = new HttpHeaders();httpHeaders.add("Content-Disposition", "attachment;filename=" + "download-name-001.jpg");// 將要下載的文件的字節流返回給瀏覽器return new ResponseEntity<>(bytes, httpHeaders, HttpStatus.OK);}

情況2：

	// 下載文件名包含中文，需要解析@PostMapping("/download2")public ResponseEntity<byte[]> download2() throws Exception {// 下載文件目錄位置FileInputStream fis = new FileInputStream("C:\\Users\\wsd\\Pictures\\susu.jpg");// 一次讀取bytes.length 個字節并將讀到的字節放入bytes數組中byte[] bytes = new byte[fis.available()];fis.read(bytes);fis.close();HttpHeaders httpHeaders = new HttpHeaders();String downloadFileName = "下載命名-001.jpg";httpHeaders.add("Content-Disposition","attachment;filename=" + URLEncoder.encode(downloadFileName,"UTF-8"));// 將要下載的文件的字節流返回給瀏覽器return new ResponseEntity<>(bytes, httpHeaders, HttpStatus.OK);}

方式二

	// 無返回值@PostMapping("/download3")public void download3(HttpServletResponse response) throws IOException {// 下載文件目錄位置FileInputStream fis = new FileInputStream("C:\\Users\\wsd\\Pictures\\susu.jpg");// 一次讀取bytes.length 個字節并將讀到的字節放入bytes數組中byte[] bytes = new byte[fis.available()];fis.read(bytes);fis.close();String downloadFileName = "下載命名-001.jpg";response.addHeader("Content-Disposition","attachment;filename=" + URLEncoder.encode(downloadFileName,"UTF-8"));response.setContentType("application/octet-stream");OutputStream os = response.getOutputStream();os.write(bytes);os.flush();os.close();}

方式三

使用 try-with-resources

	@PostMapping("/download4")public String download4(HttpServletResponse response) throws IOException {JSONObject jsonObject = new JSONObject();response.reset();response.setCharacterEncoding("utf-8");String downloadFileName = "下載命名-001.jpg";response.addHeader("Content-Disposition","attachment;filename=" + URLEncoder.encode(downloadFileName,"UTF-8"));response.setContentType("application/octet-stream");// 下載文件目錄位置String filePath = "C:\\Users\\wsd\\Pictures\\susu.jpg";// 使用 try-with-resourcestry (FileInputStream fis = new FileInputStream(filePath);OutputStream os = response.getOutputStream()) {byte[] buffer = new byte[fis.available()];int len;while ((len = fis.read(buffer)) != -1) {os.write(buffer, 0, len);}} catch (IOException e) {e.printStackTrace();}jsonObject.put("success", "下載成功");return jsonObject.toJSONString();}