Springboot 下载附件

@GetMapping("/download")
public void download(@RequestParam String fileId, HttpServletResponse response) throws IOException {// 查询文件信息SysFileEntity sysFileEntity = fileService.queryFileById(fileId);response.setContentType("application/octet-stream");response.addHeader("Content-Length", "" + sysFileEntity.getSize());  // 文件大小response.addHeader("Content-Disposition", "attachment;filename=" + URLEncoder.encode(sysFileEntity .getFileName(), "UTF-8"));int bufferSize = 8 * 1024;File file = new File(sysFileEntity.getFilePath());# 指定 读、写缓冲区大小。不填时默认 缓冲区大小8192byteBufferedInputStream bufferedInputStream = new BufferedInputStream(new FileInputStream(file), bufferSize);BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(response.getOutputStream(), bufferSize);try {// 设置缓冲区byte[] bytes = new byte[bufferSize];int len;while ((len = bufferedInputStream.read(bytes, 0, bytes.length)) > 0){bufferedOutputStream.write(bytes, 0, len);}bufferedOutputStream.flush();}catch (Exception e){logger.error("下载附件出错", e);}finally {IoUtil.close(bufferedOutputStream);IoUtil.close(bufferedInputStream);}}

注意!!!!!!

response.setContentType("application/octet-stream");
response.addHeader("Content-Length", "" + sysFileEntity.getSize());  // 文件大小
response.addHeader("Content-Disposition", "attachment;filename=" + URLEncoder.encode(sysFileEntity .getFileName(), "UTF-8"));

上述代码需写在response.getWriter或response.getOutputStream方法被调用之前。否则response.setContentType会不生效。

1. 确保在调用response.setContentType方法之前，response.getWriter或response.getOutputStream方法没有被调用。因为一旦获取了响应的输出流或写入器，设置内容类型将不起作用。

2. 确保在调用response.setContentType方法之前，没有向客户端发送任何数据。一旦开始向客户端发送数据，设置内容类型将不起作用。