MyBatis基本使用

声明：基于《基于Maven工程下的MyBatis框架+MySQL+连接池的数据查询操作》与《基于Maven工程下的MyBatis基本使用之SQL传单/多参、多表关联查询》进一步拓展，相关配置文件、数据文件可阅以上两篇。

数据插入<insert>,使用<selectKey>进行回填自动生成主键值

1<!--需要明确编写获取最新主键的SQL语句-->
2<insert id="insert" parameterType="com.imooc.mybatis.entity.Goods" flushCache="true">
3    INSERT INTO t_goods(title, sub_title, original_cost, current_price, discount, is_free_delivery, category_id)
4    VALUES (#{title} , #{subTitle} , #{originalCost}, #{currentPrice}, #{discount}, #{isFreeDelivery}, #{categoryId})
5        <!--selectKey用来回填自动生成的主键属性，last_insert_id()函数用于获取当前连接最后产生的主键ID-->
6        <selectKey resultType="Integer" keyProperty="goodsId" order="AFTER">
7            select last_insert_id()
8        </selectKey>
9    </insert>

1@Test
2    public void testInsert() throws Exception {
3        SqlSession session = null;
4        try{
5            session = MyBatisUtils.openSession();
6            Goods goods = new Goods();
7            goods.setTitle("测试插入商品");
8            goods.setSubTitle("测试子标题");
9            goods.setOriginalCost(200f);
10            goods.setCurrentPrice(100f);
11            goods.setDiscount(0.5f);
12            goods.setIsFreeDelivery(1);
13            goods.setCategoryId(43);
14            //insert()方法返回值代表本次成功插入的记录总数
15            int num = session.insert("goods.insert", goods);
16            session.commit();//提交事务数据
17            System.out.println(goods.getGoodsId());
18        }catch (Exception e){
19            if(session != null){
20                session.rollback();//回滚事务
21            }
22            throw e;
23        }finally {
24            MyBatisUtils.closeSession(session);
25        }
26    }

数据插入<insert>,使用useGeneratedKeys属性进行回填自动生成主键值

这里只需要修改<insert>元素：

1<!--根据驱动生成对应SQL语句-->
2 <insert id="insertII" parameterType="com.imooc.mybatis.entity.Goods"
3            useGeneratedKeys="true" keyProperty="goodsId" keyColumn="goods_id">
4        INSERT INTO t_goods(title, sub_title, original_cost, current_price, discount, is_free_delivery, category_id)
5        VALUES (#{title} , #{subTitle} , #{originalCost}, #{currentPrice}, #{discount}, #{isFreeDelivery}, #{categoryId})
6    </insert>

数据更新<update>

1<update id="update" parameterType="com.imooc.mybatis.entity.Goods">
2        UPDATE t_goods SET title = #{title} ,sub_title = #{subTitle} ,
3               original_cost = #{originalCost} ,current_price = #{currentPrice} ,
4               discount = #{discount} ,is_free_delivery = #{isFreeDelivery} ,
5               category_id = #{categoryId}
6        WHERE  goods_id = #{goodsId}
7    </update>

1@Test
2    public void testUpdate() throws Exception {
3        SqlSession session = null;
4        try{
5            session = MyBatisUtils.openSession();
6            Goods goods = session.selectOne("goods.selectById", 739);
7            goods.setTitle("更新测试商品");
8            int num = session.update("goods.update" , goods);
9            session.commit();//提交事务数据
10        }catch (Exception e){
11            if(session != null){
12                session.rollback();//回滚事务
13            }
14            throw e;
15        }finally {
16            MyBatisUtils.closeSession(session);
17        }
18    }

数据删除<detele>

1<!--根据主键删除-->
2<delete id="delete" parameterType="Integer">
3        delete from t_goods where goods_id = #{value} 
4</delete>

1@Test
2    public void testDelete() throws Exception {
3        SqlSession session = null;
4        try{
5            session = MyBatisUtils.openSession();
6            int num = session.delete("goods.delete" , 739);
7            session.commit();//提交事务数据
8        }catch (Exception e){
9            if(session != null){
10                session.rollback();//回滚事务
11            }
12            throw e;
13        }finally {
14            MyBatisUtils.closeSession(session);
15        }
16    }