JDBC——事务

public static void main(String[] args) {
    Connection  conn=null;
    PreparedStatement pstmt = null;
    PreparedStatement pstmt2 = null;
    try {
        conn = JDBCUtils.getConnection();
        conn.setAutoCommit(false);//开启事务
        String sql = "update acount set balance=balance - ? where id=?";
        String sql2 = "update acount set balance=balance + ? where id=?";
        pstmt = conn.prepareStatement(sql);
        pstmt2 =conn.prepareStatement(sql2);
        pstmt.setDouble(1,500);
        pstmt.setInt(2,1);
        pstmt2.setDouble(1,500);
        pstmt2.setInt(2,2);
        pstmt.executeUpdate();
        pstmt2.executeUpdate();
        conn.commit();//所有sql语句执行完毕以后提交事务
    } catch (Exception e) {
        try {
            //只要出现异常就进行回滚操作，所以在catch里写回滚操作；
            //同时将捕获异常扩展为最高父类
           if(conn!=null) conn.rollback();
        } catch (SQLException e1) {
            e1.printStackTrace();
        }
        e.printStackTrace();
    }finally {
        JDBCUtils.close(conn,pstmt);
        try {
            pstmt2.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}