// File file = xxx
InputStream inStream = new FileInputStream(file);
try {
String fileName = file.getName();
response.setHeader("Content-Disposition", "attachment; filename=" + fileName); // HttpServletResponse
response.addHeader("Content-Length", "" + inStream.available());
response.setContentType("application/octet-stream; charset=UTF-8");
// 后面再来考虑支持断点续传。
IOUtils.copy(inStream, response.getOutputStream());
} finally {
IOUtils.closeQuietly(inStream);
}
