java获取文件流

@RequestMapping(value = "preView", method = RequestMethod.GET)
public void preView(HttpServletResponse response){
    File file = new File("C:\\Users\\admin\\Desktop\\新建文本文档.txt");
    if (file.exists()){
        byte[] data = null;
        try {
            FileInputStream input = new FileInputStream(file);
            data = new byte[input.available()];
            input.read(data);
            response.getOutputStream().write(data);
            input.close();
        } catch (Exception e) {
            System.out.println(e);
        }
    }else{
        return;
    }

}