Springboot 导出csv文件

```
@GetMapping(value = "/file/{fileName}")
public ResponseEntity<FileSystemResource> getFile(@PathVariable("fileName") String fileName) throws FileNotFoundException {
	File file = new File(filePath, fileName);
	if (file.exists()) {
		return export(file);
	}
	System.out.println(file);
	return null;
}

public ResponseEntity<FileSystemResource> export(File file) {
	if (file == null) {
		return null;
	}
	HttpHeaders headers = new HttpHeaders();
	// 关键，指定为文件
	headers.add("Content-Type", "application/octet-stream;charset=utf-8");
	// 指定文件名
	headers.add("Content-Disposition", "attachment; filename=" + file.getName());
	// 设置过期时间用
	headers.add("Cache-Control", "no-cache, no-store, must-revalidate");
	headers.add("Pragma", "no-cache");
	headers.add("Expires", "0");
	headers.add("Last-Modified", new Date().toString());
	headers.add("ETag", String.valueOf(System.currentTimeMillis()));
	return ResponseEntity.ok().headers(headers).contentLength(file.length()).contentType(MediaType.parseMediaType("application/octet-stream")).body(new FileSystemResource(file));
```

hutool导出csv文件
```
public static File buildFile(String filename, Collection<String[]> body) {
  File file = FileUtil.touch(filename);
  byte[] utf8bom = {(byte) 0xEF, (byte)0xBB, (byte)0xBF};
  FileUtil.writeBytes(utf8bom, file);
  CsvWriter writer = CsvUtil.getWriter(file, CharsetUtil.CHARSET_UTF_8, true);
  writer.write(body);
  writer.flush();
  writer.close();
  return file;
}

```

参考链接：
导出文件流 https://blog.csdn.net/han1396735592/article/details/103128588
csv在excel乱码问题的解决方案 https://www.jianshu.com/p/fad568d89a29