一对多映射中无法获取多的一方【急】

[ppmmwozuiai]

目的：列出所有具有下级Router的Router
问题：下级Router的集合size=0

其中使用upper_router_id字段引用本表的id
建表：

drop table IF EXISTS t_data_router;
CREATE TABLE IF NOT EXISTS t_data_router (
id  BIGINT unsigned primary key,
name varchar(128) not null unique,
upper_router_id BIGINT unsigned,
as_terminal bit(1) not null,
hostname varchar(256) not null,
ip_address varchar(256),
description varchar(256)
);

映射配置

@Entity
@Table(name = "t_data_router")
public class DataRouter {

	private Long id;
	private String name;
	private String hostname;
	private String ipAddress;
	private Boolean terminal;
	private DataRouter upperRouter;
	private Set<DataRouter> lowerRouters = new HashSet<DataRouter>();
	private String description;

	@Id
	@GeneratedValue(generator = "shortUid")
	@GenericGenerator(name = "shortUid", strategy = "dataroute.base.generator.ShortUUIDIncrementGenerator")
	@Column(name = "id", columnDefinition = "BIGINT")
	public Long getId() {
		return id;
	}

	public void setId(Long id) {
		this.id = id;
	}

	@Column(name = "name")
	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	@Column(name = "hostname")
	public String getHostname() {
		return hostname;
	}

	public void setHostname(String hostname) {
		this.hostname = hostname;
	}

	@Column(name = "ip_address")
	public String getIpAddress() {
		return ipAddress;
	}

	public void setIpAddress(String ipAddress) {
		this.ipAddress = ipAddress;
	}

	@Column(name = "as_terminal", columnDefinition = "BOOLEAN")
	public Boolean getTerminal() {
		return terminal;
	}

	public void setTerminal(Boolean terminal) {
		this.terminal = terminal;
	}

	@Column(name = "description")
	public String getDescription() {
		return description;
	}

	public void setDescription(String description) {
		this.description = description;
	}

	@ManyToOne
	@JoinColumn(name = "upper_router_id")
	public DataRouter getUpperRouter() {
		return upperRouter;
	}

	public void setUpperRouter(DataRouter upperRouter) {
		this.upperRouter = upperRouter;
	}

	@OneToMany(cascade = CascadeType.ALL)
	@JoinColumn(name = "upper_router_id")
	public Set<DataRouter> getLowerRouters() {
		return lowerRouters;
	}

	public void setLowerRouters(Set<DataRouter> lowerRouters) {
		this.lowerRouters = lowerRouters;
	}

}

DAO中的查询代码

@SuppressWarnings("unchecked")
	public <T> List<T> listQ(Class<T> c, String key, Object value) {
		Query q = getSession().createQuery("from " + c.getSimpleName() + " where " + key + " = " + value);
		return (List<T>) q.list();
	}

目前的情况：hibernate已将SQL生成，但是获取下级router的size=0
将SQL复制到数据库中可以正确执行

Hibernate: 
    select
        datarouter0_.id as id1_1_,
        datarouter0_.description as descript2_1_,
        datarouter0_.hostname as hostname3_1_,
        datarouter0_.ip_address as ip_addre4_1_,
        datarouter0_.name as name5_1_,
        datarouter0_.as_terminal as as_termi6_1_,
        datarouter0_.upper_router_id as upper_ro7_1_ 
    from
        t_data_router datarouter0_ 
    where
        datarouter0_.as_terminal=0
Hibernate: 
    select
        lowerroute0_.upper_router_id as upper_ro7_1_0_,
        lowerroute0_.id as id1_1_0_,
        lowerroute0_.id as id1_1_1_,
        lowerroute0_.description as descript2_1_1_,
        lowerroute0_.hostname as hostname3_1_1_,
        lowerroute0_.ip_address as ip_addre4_1_1_,
        lowerroute0_.name as name5_1_1_,
        lowerroute0_.as_terminal as as_termi6_1_1_,
        lowerroute0_.upper_router_id as upper_ro7_1_1_ 
    from
        t_data_router lowerroute0_ 
    where
        lowerroute0_.upper_router_id=?
=============================0

[ppmmwozuiai]

PS：使用急加载