一对多映射中无法获取多的一方【急】

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