MyBatis Learning (eight)

This tutorial corresponds to the video course address: http://edu.51cto.com/sd/3ec2c

1. Delayed loading

The significance of lazy loading is that although it is an associative query, it is not timely to query the associated data, but to query when needed

1.1. Lazy Load SQL Analysis

select * from tb_order where order_number=‘20180810001‘select * from tb_user where userid=2

1.2. Global configuration File Settings

<!-- 开启延迟加载 --><setting name="lazyLoadingEnabled" value="true"/><!-- 按需要加载 --><setting name="aggressiveLazyLoading" value="false"/>

1.3. Define the interface method

public List<Order> queryLazy(@Param("orderNum")String orderNum);

1.4. mapper.xml file Configuration

<resultMap type="Order" id="lazyOrderMap" autoMapping="true">    <id column="oid" property="oid"/>    <association property="user" javaType="User" column="user_id" select="selectById"/>  </resultMap>  <select id = "selectById" resultType="User">    select * from tb_user where userid=#{userid}  </select>  <select id = "queryLazy" resultMap="lazyOrderMap">        select * from tb_order where order_number=#{orderNum}  </select>

1.5. Test method

@Test    public void testLazy()throws Exception{        List<Order> list = orderMapper.queryLazy("20180810001");        for (Order order : list) {            System.out.println(order.getOid());        }    }

1.6. Observation Log

DEBUG - Opening JDBC ConnectionDEBUG - Created connection 80004644.DEBUG - Setting autocommit to false on JDBC Connection [[email protected]]DEBUG - ==>  Preparing: select * from tb_order where order_number=? DEBUG - ==> Parameters: 20180810001(String)DEBUG - <==      Total: 11DEBUG - Resetting autocommit to true on JDBC Connection [[email protected]]DEBUG - Closing JDBC Connection [[email protected]]DEBUG - Returned connection 80004644 to pool.

Modify the code, call the Lazy property operation, observe the log again

DEBUG - Setting autocommit to false on JDBC Connection [[email protected]]DEBUG - ==>  Preparing: select * from tb_order where order_number=? DEBUG - ==> Parameters: 20180810001(String)DEBUG - <==      Total: 11DEBUG - Cache Hit Ratio [cn.org.kingdom.mapper.OrderMapper]: 0.0DEBUG - ==>  Preparing: select * from tb_user where userid=? DEBUG - ==> Parameters: 2(BigDecimal)DEBUG - <==      Total: 1阿柯DEBUG - Resetting autocommit to true on JDBC Connection [[email protected]]DEBUG - Closing JDBC Connection [[email protected]]DEBUG - Returned connection 313288686 to pool.

2. MyBatis Call stored Procedure 2.1, MyBatis call no parameter stored procedure

1, first to define a parameter-free stored procedure

create or replace procedure mypro isbegin  insert into dept(deptno,dname,loc) values(60,‘销售部‘,‘北京‘);  commit;end mypro;

2. Define the interface method

public void callPro();

3. Define Mapper File

 <select id = "callPro" statementType="CALLABLE">    {call mypro}  </select>

4. Write Test class

@Test    public void callpro1()throws Exception{        orderMapper.callPro();    }

2.2. Call a stored procedure with parameters

Define a stored procedure that has parameters

create or replace procedure pro_getUserNameById(v_userid in tb_user.userid%type,v_username out tb_user.user_name%type) isbegin           select user_name into v_username from tb_user where userid=v_userid;end pro_getUserNameById;

interface method definition

public void callPro2(User vo);

Configuration of the Mapper.xml file

<!-- 调用有参数的     useCache="false"    定义入参和出参    jdbcType：大家参考org.apache.ibatis.type.JdbcType  -->  <select id = "callPro2" useCache="false" statementType="CALLABLE">    {call pro_getusernamebyid(        #{userid,mode=IN,jdbcType=INTEGER,javaType=int},        #{userName,mode=OUT,jdbcType=VARCHAR,javaType=string}    )}  </select>

Test method

@Test    public void callpro2()throws Exception{        User user = new User();        user.setUserid(2);        orderMapper.callPro2(user);        System.out.println(user.getUserName());    }

Log information

DEBUG - Opening JDBC ConnectionDEBUG - Created connection 1723550754.DEBUG - Setting autocommit to false on JDBC Connection [[email protected]]DEBUG - ==>  Preparing: {call pro_getusernamebyid( ?, ? )} DEBUG - ==> Parameters: 2(Integer)阿柯DEBUG - Resetting autocommit to true on JDBC Connection [[email protected]]DEBUG - Closing JDBC Connection [[email protected]]DEBUG - Returned connection 1723550754 to pool.

MyBatis Learning (eight)