Mybatis中的延迟加载详细解析

public interface IAccountDao {
    /**
     * 查询所有账户，同时还要获取到当前账户的所属用户信息
     * @return
     */
    List<Account> findAll();
    }

<resultMap id="accountUserMap" type="account">
        <id property="id" column="id"></id>
        <result property="uid" column="uid"></result>
        <result property="money" column="money"></result>
        <!-- 一对一的关系映射：配置封装user的内容
        select属性制定的内容：查询用户的唯一标识
         column属性指定的内容：用户根据id时，所需要的参数值的值-->
        <association property="user" column="uid" javaType="user" select="com.rpf.dao.IUserDao.findById"></association>
    </resultMap>
    <!-- 查询所有 -->
    <select id="findAll" resultMap="accountUserMap">
        select * from account
    </select>

<!--加入settings-->
   <settings>
        <!--开启Mybatis支持延迟加载-->
        <setting name="lazyLoadingEnabled" value="true"/>
        <setting name="aggressiveLazyLoading" value="false"></setting>
    </settings>

@Test
 public void testFindAll(){
        List<Account> accounts = accountDao.findAll();
    }

//user
  <resultMap id="userAccountMap" type="user">
        <id property="id" column="id"></id>
        <result property="username" column="username"></result>
        <result property="address" column="address"></result>
        <result property="sex" column="sex"></result>
        <result property="birthday" column="birthday"></result>
        <!-- 配置user对象中accounts集合的映射 -->
        <collection property="accounts" ofType="account" select="com.rpf.dao.AccountDao.findAccountByUid" column="id"></collection>
    </resultMap>
    <!-- 查询所有 -->
    <select id="findAll" resultMap="userAccountMap">
        select * from user
    </select>
    <!-- 根据id查询用户 -->
    <select id="findById" parameterType="INT" resultType="user">
        select * from user where id = #{uid}
    </select>

<!-- 根据用户id查询账户列表 account -->
    <select id="findAccountByUid" resultType="account">
        select * from account where uid=#{uid}
    </select>

  @Test
    public void testFindAll(){
        List<User> users = userDao.findAll();
    }