Connection con=null;

        PreparedStatement ps=null;

        ResultSet rs=null;

        try {

            //建立连接

            con= JDBCUtils.getConnection();

            //创建语句

            String sql="insert into t_user values('test','123',null,null)";

            ps = con.prepareStatement(sql,Statement.RETURN_GENERATED_KEYS);

            ps.executeUpdate();

            rs= ps.getGeneratedKeys();//获取主键集合

            if (rs.next()) {

                System.out.println(rs.getInt(1));//获取主键

            }