java怎么下载文件到服务器 java文件下载

public AjaxResult uploadStart(HttpServletResponse response) {
        //获取项需要下载的文件路径
        String path = this.getClass().getResource("/").getPath() + "static/启动.txt";
        //通过路径，得到文件
        File file = new File(path);
        //判断文件是否存在
        if(!file.exists()){
            return AjaxResult.error("文件不存在！");
        }
        FileInputStream fileInputStream = null;
        OutputStream outputStream = null;

        try {
            fileInputStream = new FileInputStream(file);
            //设置Http响应头
            response.setHeader("Content-Disposition", "attachment;Filename=" + URLEncoder.encode("启动.txt", "UTF-8"));
            response.setContentType("application/octet-stream; charset=UTF-8");

            outputStream = response.getOutputStream();
            byte[] bytes = new byte[2048];
            int len;
            while ((len = fileInputStream.read(bytes))>0){
                outputStream.write(bytes,0,len);
            }
        }catch(Exception e) {
            e.printStackTrace();
            return AjaxResult.error("系统异常！");
        }finally {
            if (outputStream != null) {
                try {
                    outputStream.close();
                } catch (IOException e1) {
                    e1.printStackTrace();
                }
            }
            if (fileInputStream != null) {
                try {
                    fileInputStream.close();
                } catch (IOException e1) {
                    e1.printStackTrace();
                }
            }
        }
        return AjaxResult.success();
    }