初用jdbc来运行事务

dao层

    public Connection getConnection() throws Exception {
        Class.forName(driver);
        if (con == null || con.isClosed()) {
            con = DriverManager.getConnection(url, username, password);
        }
        return con;
    }
//这是一个链接数据库的方法 

impl层

    public void fromToBank(String name, double money) {
        try {

            String sql = "UPDATE bank SET money=money+? WHERE `name`=?";
            Object[] params = {money, name};
            int num = executeUpdate(sql, params);
            if (num > 0) {
                System.out.println("成功");
            } else {
                System.out.println("失败");
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
//这是一个修改方法

    @Test  //事务
    public void text2() throws Exception {
        try {
            super.con = getConnection(); //连接sql方法
            con.setAutoCommit(false); //关闭自动提交事务
            fromToBank("小黑", -1000);
            if (true) {
                throw new Exception("转账失败========");
            }
            fromToBank("小白", 1000);
            con.commit(); //事物提交
        } catch (Exception e) {
            e.printStackTrace();
            try {
                con.rollback(); //事物回滚
            } catch (SQLException e1) {
                e1.printStackTrace();
            }

        }
    }