Mybatis如何实现关联属性懒加载

<!-- 关联属性延迟加载 -->
	<select id="queryOrderAndUser" resultMap="orderAndUser">
		select
		o.id oids,o.orderid,o.createtime,o.note,o.userid
		from orders o,t_user u
		where o.userid=u.id
	</select>
	<resultMap type="orders" id="orderAndUser">
		<id property="id" column="oids"></id>
		<result property="orderId" column="orderid"></result>
		<result property="createtime" column="createtime" />
		<result property="note" column="note" />
		<association property="user" javaType="users" 
		select="net.neuedu.mybatis.mapper.UserMapper.queryUserById" column="userid">
			<!-- 
				这里不查询用户的信息，而是将用的信息放在另外一个查询中
				column是order表中的userid字段
			 -->
		</association>
	</resultMap>

 //根据ID查询用户
 public Users queryUserById(Integer id);

 <!-- public Users queryUserById(Integer id); -->
 <select id="queryUserById" parameterType="int" resultType="users">
  select * from t_user where id=#{id}
 </select>

<!-- 查询时，关闭关联对象即时加载以提高性能 -->
<setting name="lazyLoadingEnabled" value="true" />
<!-- 设置关联对象加载的形态，此处为按需加载字段(加载字段由SQL指 定)，不会加载关联表的所有字段，以提高性能 -->
<setting name="aggressiveLazyLoading" value="false" />

@Select("select * from user_main where username=#{username}")
 @Results({
       @Result(property = "roleNames", column = "id", many = @Many(fetchType=FetchType.LAZY,select = "getRoleNamesByUserId")),
       @Result(property = "permissionNames", column = "id", many = @Many(fetchType=FetchType.LAZY,select = "getPermissionsByUserId"))
   })
public UserPO getUserByUsername(@Param("username")String username);

 @Test
   public void testGetUserByUsername() throws Exception {
     SqlSession session = sqlSessionFactory.openSession();
     try {
       UserMapper userMapper = session.getMapper(UserMapper.class);
       UserPO userPo = userMapper.getUserByUsername("zhangsan");
       System.out.println(userPo);
       System.out.println(userPo.getPermissionNames());
//       List<String> map = userMapper.getRoleMain();
//       System.out.println(map);
       session.close();
     } finally {
       session.close();
     }
   }

protected Set<String> lazyLoadTriggerMethods = new HashSet<String>(Arrays.asList(new String[] { "equals", "clone", "hashCode", "toString" }));

configuration.setLazyLoadTriggerMethods(new HashSet<String>());