Java Spring MVC 文件下载

@RequestMapping("/testResponseEntity")
public ResponseEntity<byte[]> testResponseEntity(HttpSession session) throws Exception{
byte[] body=null;
ServletContext servletContext = session.getServletContext();
InputStream in = servletContext.getResourceAsStream("/file/abc.txt");
body = new byte[in.available()];
in.read(body);

HttpHeaders headers = new HttpHeaders();
headers.add("Content-Disposition", "attachment;filename=abc.txt");

HttpStatus statusCode = HttpStatus.OK;
ResponseEntity<byte[]> response = new ResponseEntity<byte[]>(body, headers, statusCode);

return response;
}