hibernate的继承映射

DOVEty

2010-06-30

hibernate的继承映射有三种策略：joined_table、single_table、table_per_class

我们今天使用single_table作为例子

domain：

/**
 * 
 * {好友类型的抽象父类信息}
 * @author jerome
 * @version 1.0.0
 * 
 */
@javax.persistence.Entity
@javax.persistence.Table(name = "mag_friend_type_common")
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name = "friend_type",
		discriminatorType=DiscriminatorType.INTEGER)
public abstract class FriendSuper {

	// 主键
	private Long ftcId;
	
	// 类型名称
	private String ftcName;

	/**
	 * the getter method of ftcId
	 * @return the ftcId
	 */
	@Id
	@Column(name="ftd_id", length=20)
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	public Long getFtcId() {
		return ftcId;
	}

	/**
	 * the setter method of the ftcId
	 * @param ftcId the ftcId to set
	 */
	public void setFtcId(Long ftcId) {
		this.ftcId = ftcId;
	}

/**
 * {实体类FriendTypeCommon，对应mag_friend_type_common表}
 * @author jerome
 * @version 1.0.0
 * 
 */
@javax.persistence.Entity
//@DiscriminatorColumn(discriminatorType = DiscriminatorType.INTEGER)
@DiscriminatorValue("0")
@Cache(usage = CacheConcurrencyStrategy.READ_ONLY,region="personalEmp") 
public class FriendTypeCommon extends FriendSuper implements Serializable {

	private static final long serialVersionUID = 1L;

}

/**
 * {实体类FriendTypeDiy，对应mag_friend_type_common表}
 * @author jerome
 * @version 1.0.0
 *
 */

@javax.persistence.Entity
//@DiscriminatorColumn(discriminatorType = DiscriminatorType.INTEGER)
@DiscriminatorValue("1")
public class FriendTypeDiy extends FriendSuper implements Serializable {

	// serialVersionUID
	private static final long serialVersionUID = 1L;
	
	
	// 外键，关联实体类UserMain
	private UserMain userMain;


	/**
	 * the getter method of userMain
	 * @return the userMain
	 */
	@ManyToOne(fetch=FetchType.LAZY)
	@JoinColumn(name="user_id", nullable=false)
	public UserMain getUserMain() {
		return userMain;
	}


	/**
	 * the setter method of the userMain
	 * @param userMain the userMain to set
	 */
	public void setUserMain(UserMain userMain) {
		this.userMain = userMain;
	}
}

junit测试得：

公共类型：

对FriendTypeCommon对象操作：
Hibernate: select this_.ftd_id as ftd2_0_0_, this_.ftd_name as ftd3_0_0_ from mag_friend_type_common this_ where this_.friend_type=0
同学
朋友

自定义类型：

FriendTypeDiy：
Hibernate: select this_.ftd_id as ftd2_0_1_, this_.ftd_name as ftd3_0_1_, this_.user_id as user4_0_1_, um1_.user_id as user1_1_0_, um1_.user_code as user2_1_0_, um1_.user_password as user3_1_0_, um1_.user_gender as user4_1_0_, um1_.user_date_of_birth as user5_1_0_, um1_.user_image as user6_1_0_, um1_.user_email as user7_1_0_, um1_.user_remark as user8_1_0_, um1_.user_name as user9_1_0_ from mag_friend_type_common this_ inner join mag_user_main um1_ on this_.user_id=um1_.user_id where this_.friend_type=1 and um1_.user_id=?
我的亲戚

hibernate table