@RequestMapping( value = "download",method = RequestMethod.GET)
public void downloadFile(HttpServletRequest request, HttpServletResponse response) {
    File file = new File("C:\\Users\\lenovo\\Desktop\\timg.jpg");
    String[]fileType=file.getName().split("\\.");
        Map map=new HashMap();
        map.put("jpg", "image/jpeg;");
        map.put("xls", "application/x-xls;");
        map.put("xlsx", "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet;");
        map.put("doc", "application/msword;");
        map.put("docx", "application/vnd.openxmlformats-officedocument.wordprocessingml.document;");
        map.put("txt", "text/plain;");
    try {
        FileInputStream inputStream = new FileInputStream(file);
        byte[] bytes = new byte[inputStream.available()];
        inputStream.read(bytes);
        String fileName = URLEncoder.encode(file.getName(), "UTF-8");
        response.reset();
        response.setHeader("Content-Disposition", "attachment; filename="+fileName);
        response.setCharacterEncoding("UTF-8");
        response.setContentType(map.get(fileType[fileType.length-1])+" charset=utf-8");
        OutputStream outputStream = response.getOutputStream();
        outputStream.write(bytes);  //也可以使用
        outputStream.close();
        outputStream.flush();
        inputStream.close();
    } catch (IOException e) {
        e.printStackTrace();
    }
    
}
 

ps:mime型別可自行百度