Hibernate 休眠许多相同的列名称
我有两个实体类Hibernate 休眠许多相同的列名称,hibernate,orm,many-to-many,hibernate-mapping,hibernate-4.x,Hibernate,Orm,Many To Many,Hibernate Mapping,Hibernate 4.x,我有两个实体类Activity和User。它们之间的关系是: 一个活动可以有一个或多个用户 一个用户可以属于一个或多个活动 为了实现这一点,我定义了它们之间的映射。以下是我的课程: 活动: @javax.persistence.Entity @Table(name = "ACTIVITY") public class Activity extends Entity { @Transient private static final long serialVersionUID
Activity
和User
。它们之间的关系是:
- 一个
可以有一个或多个活动
用户
- 一个
可以属于一个或多个用户
活动
活动
:
@javax.persistence.Entity
@Table(name = "ACTIVITY")
public class Activity extends Entity {
@Transient
private static final long serialVersionUID = 4741665931936809028L;
private Set<User> users;
public Activity() {
super();
}
@ManyToMany(targetEntity = User.class, cascade = { CascadeType.ALL })
@JoinTable(name = "ACTIVITY_USER", joinColumns = @JoinColumn(name = "ID"), inverseJoinColumns = @JoinColumn(name = "ID"))
public Set<User> getUsers() {
return users;
}
public void setUsers(Set<User> users) {
this.users = users;
}
}
@MappedSuperclass
public class Entity implements Serializable {
@Transient
private static final long serialVersionUID = 7470288121057059283L;
private Long id;
public Entity() {
super();
}
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "ID", updatable = false, nullable = false, unique = true)
public Long getId() {
return id;
}
@SuppressWarnings("unused")
private void setId(Long id) {
this.id = id;
}
public void setLastUpdateTimestamp(Date lastUpdateTimestamp) {
this.lastUpdateTimestamp = lastUpdateTimestamp;
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
return prime * result + ((getId() == null) ? super.hashCode() : getId().hashCode());
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null) {
return false;
}
if (!getClass().equals(HibernateProxyHelper.getClassWithoutInitializingProxy(obj))) {
return false;
}
final Entity other = (Entity) obj;
if (getId() != other.getId()) {
if (getId() == null) {
return false;
}
if (!getId().equals(other.getId())) {
return false;
}
}
return true;
}
}
上述两个类都扩展了实体
:
@javax.persistence.Entity
@Table(name = "ACTIVITY")
public class Activity extends Entity {
@Transient
private static final long serialVersionUID = 4741665931936809028L;
private Set<User> users;
public Activity() {
super();
}
@ManyToMany(targetEntity = User.class, cascade = { CascadeType.ALL })
@JoinTable(name = "ACTIVITY_USER", joinColumns = @JoinColumn(name = "ID"), inverseJoinColumns = @JoinColumn(name = "ID"))
public Set<User> getUsers() {
return users;
}
public void setUsers(Set<User> users) {
this.users = users;
}
}
@MappedSuperclass
public class Entity implements Serializable {
@Transient
private static final long serialVersionUID = 7470288121057059283L;
private Long id;
public Entity() {
super();
}
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "ID", updatable = false, nullable = false, unique = true)
public Long getId() {
return id;
}
@SuppressWarnings("unused")
private void setId(Long id) {
this.id = id;
}
public void setLastUpdateTimestamp(Date lastUpdateTimestamp) {
this.lastUpdateTimestamp = lastUpdateTimestamp;
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
return prime * result + ((getId() == null) ? super.hashCode() : getId().hashCode());
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null) {
return false;
}
if (!getClass().equals(HibernateProxyHelper.getClassWithoutInitializingProxy(obj))) {
return false;
}
final Entity other = (Entity) obj;
if (getId() != other.getId()) {
if (getId() == null) {
return false;
}
if (!getId().equals(other.getId())) {
return false;
}
}
return true;
}
}
现在从:
@JoinTable(name = "ACTIVITY_USER", joinColumns = @JoinColumn(name = "ID"), inverseJoinColumns = @JoinColumn(name = "ID"))
据我所知,joinColumns
的@JoinColumn
的名称取一个实体PK的列名,inverseJoinColumns
的@JoinColumn
的名称取另一个实体PK的列名。但在我的例子中,这两个列名是相同的,即实体
类中的ID
我的问题是如何避免列名之间的冲突?任何建议都会对我很有帮助。在同一个表中有两个名称相同的列是没有意义的。因此,只需为列选择一个不同的名称 改变
@JoinTable(name = "ACTIVITY_USER",
joinColumns = @JoinColumn(name = "ID"),
inverseJoinColumns = @JoinColumn(name = "ID"))
到
如属性名称所示,您在此处给出的名称是联接表的联接列的名称,即联接表activity\u user中包含活动或用户表外键的列的名称。Hibernate已经知道用户和活动PK的名称:您在各自的
@Id
注释中告诉了它。在同一个表中有两个名称相同的列是没有意义的。因此,只需为列选择一个不同的名称
改变
@JoinTable(name = "ACTIVITY_USER",
joinColumns = @JoinColumn(name = "ID"),
inverseJoinColumns = @JoinColumn(name = "ID"))
到
如属性名称所示,您在此处给出的名称是联接表的联接列的名称,即联接表activity\u user中包含活动或用户表外键的列的名称。Hibernate已经知道用户和活动的PK名称:您在各自的
@Id
注释中告诉了它。非常感谢您对PK的解释,我错了。非常感谢您对PK的解释,我错了。