连接池（链接druid.properties）

    public static void main(String[] args) {

        try {
            Properties p =new Properties();
            p.load(Thread.currentThread().getContextClassLoader().getResourceAsStream("druid.properties"));
            DataSource ds =DruidDataSourceFactory.createDataSource(p);
            QueryRunner run =new QueryRunner(ds);

           String ver =run.query("select version()",new ScalarHandler<>());
           System.out.println(ver);
        } catch (Exception e) {
            e.printStackTrace();
        }

    }