在后台页面上导出数据库文件，即通过 mysqldump 数据库为 sql 文件，然后下载下来

直接上代码

    /**
     * 下载SQL
     *
     * @param response
     * @throws IOException
     */
    @RequestMapping(value = "/exportSql", method = RequestMethod.GET)
    public void downloadFile(
            HttpServletResponse response) throws IOException {
        String exportPath = mysqldump();
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd-HH-mm-ss");

        InputStream f = new FileInputStream(new File(exportPath));
        response.reset();
        response.setContentType("application/x-msdownload;charset=utf-8");
        response.setHeader("Content-Disposition", "attachment;filename=" + sdf.format(new Date()) + ".sql");//下载文件的名称
        ServletOutputStream sout = response.getOutputStream();
        BufferedInputStream bis = null;
        BufferedOutputStream bos = null;
        try {
            bis = new BufferedInputStream(f);
            bos = new BufferedOutputStream(sout);
            byte[] buff = new byte[2048];
            int bytesRead;
            while (-1 != (bytesRead = bis.read(buff, 0, buff.length))) {
                bos.write(buff, 0, bytesRead);
            }
            bos.flush();
            bos.close();
            bis.close();
        } catch (final IOException e) {
            throw e;
        } finally {
            if (bis != null) {
                bis.close();
            }
            if (bos != null) {
                bos.close();
            }
        }
    }

    public static String mysqldump() {
        Runtime runtime = Runtime.getRuntime();
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd-HH-mm-ss");

        String exportPath = "/www/mysqldump/" + sdf.format(new Date()) + ".sql";
        String command = getExportCommand(exportPath);
        // 这里其实是在命令窗口中执行的 command 命令行
        try {
            runtime.exec(command);
            return exportPath;
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }

    // 得到导出数据的命令行语句
    private static String getExportCommand(String exportPath) {
        StringBuffer command = new StringBuffer();
        String username = "root";// 用户名
        String password = "123456";// 密码
        String host = "localhost";// 导入的目标数据库所在的主机
        String port = "3306";// 使用的端口号
        String exportDatabaseName = "house_key";// 导入的目标数据库的名称
        String MysqlPath = "/www/server/mysql/bin/"; //路径是mysql中
        // 注意哪些地方要空格，哪些不要空格
        command.append(MysqlPath).append("mysqldump -u").append(username).append(" -p").append(password)// 密码是用的小p，而端口是用的大P。
                .append(" -h").append(host).append(" -P").append(port).append(" ").append(exportDatabaseName)
                .append(" -r ").append(exportPath);
        return command.toString();
    }