Data Access 之 MyBatis（三） - SQL Mapping XML（Part C）（下）

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.citi.dao.LockDao">
    <select id="getLockById" resultMap="mylock">
        SELECT l.id,l.lockName,k.id kid, k.keyname,k.lockid
            FROM t_lock l
            LEFT JOIN t_key k ON l.id = k.lockid
            WHERE l.id=#{id}
    </select>
    <resultMap id="mylock" type="com.citi.entity.Lock">
        <id property="id" column="id"></id>
        <result property="lockName" column="lockName"></result>
        <collection property="keyList" ofType="com.citi.entity.Key">
            <!--column是起的别名，如果没起别名，就和数据库列字段一致-->
            <id property="id" column="kid"></id>
            <result property="keyName" column="keyName"></result>
        </collection>
    </resultMap>
</mapper>
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<mappers>
    <mapper resource="mappers/employee.xml"/>
    <mapper resource="mappers/cat.xml"/>
    <mapper resource="mappers/key.xml"/>
    <mapper resource="mappers/lock.xml"/>
</mappers>
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public class LockDaoTest {
    SqlSessionFactory sqlSessionFactory = null;
    SqlSession openSession = null;
    @Before
    public void setUp() throws Exception {
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        openSession = sqlSessionFactory.openSession();
    }
    @Test
    public void getLockById() {
        LockDao lockDao = openSession.getMapper(LockDao.class);
        Lock lock = lockDao.getLockById(3);
        System.out.println(lock);
        List<Key> keyList = lock.getKeyList();
        for (Key key : keyList) {
            System.out.println("Key：" + key);
        }
    }
}
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Lock getLockByIdSimplely(Integer id);
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Key getKeyByIdSimplely(Integer id);
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<select id="getLockByIdSimplely" resultType="com.citi.entity.Cat">
    select * from t_lock where id = #{id}
</select>
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<select id="getKeyByIdSimplely" resultMap="mykeysimplely">
    select * from t_key where id = #{id}
</select>
<resultMap id="mykeysimplely" type="com.citi.entity.Key">
    <id property="id" column="id"></id>
    <result property="keyName" column="keyname"></result>
    <association property="lock"
                 select="com.citi.dao.LockDao.getLockByIdSimplely"
                 column="lockid">
    </association>
</resultMap>
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@Test
public void getKeyByIdSimplely() {
    KeyDao keyDao = openSession.getMapper(KeyDao.class);
    Key key = keyDao.getKeyByIdSimplely(1);
    System.out.println(key);
}
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<settings>
    <setting name="lazyLoadingEnabled" value="true"/>
    <setting name="aggressiveLazyLoading" value="true"/>
</settings>
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@Test
public void getKeyByIdSimplely() {
    KeyDao keyDao = openSession.getMapper(KeyDao.class);
    Key key = keyDao.getKeyByIdSimplely(1);
    // System.out.println(key);
    String lockName = key.getLock().getLockName();
    System.out.println(lockName);
}
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Lock getLockByIdStep(Integer id);
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List<Key> getKeysByLockId(Integer id);
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<select id="getKeysByLockId" resultType="com.citi.entity.Key">
    select * from t_key where lockid = #{id}
</select>
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<select id="getLockByIdStep" resultMap="mylockstep">
    select * from t_lock where id = #{id}
</select>
<resultMap id="mylockstep" type="com.citi.entity.Lock">
    <id property="id" column="id"></id>
    <result property="lockName" column="lockName"></result>
    <collection property="keyList"
                select="com.citi.dao.KeyDao.getKeysByLockId"
                column="id">
    </collection>
</resultMap>
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@Test
public void getLockByIdStep() {
    LockDao lockDao = openSession.getMapper(LockDao.class);
    Lock lock = lockDao.getLockByIdStep(3);
    System.out.println(lock);
    List<Key> keyList = lock.getKeyList();
    for (Key key : keyList) {
        System.out.println("Key：" + key);
    }
}
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