如何在hibernate注释类中将两列作为主键

Question

这是我的注释类,我想userId和groupId列都作为主键.我发现了更多关于此的问题(问题),但未找到相关答案.我的声誉较少,所以我无法评论帖子,所以我在这里提出我的问题.

这是我的代码..

import javax.persistence.Column;
import javax.persistence.EmbeddedId;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

import org.hibernate.annotations.NaturalId;

@Entity
@Table(name="user_group")
public class user_group {

@Column(name="serviceProvider")
private String serviceProvider;

@Column(name="enterpriseId")
private String enterpriseId;

@Column(name="department")
private String department;

@Column(name="trunkGroupName")
private String trunkGroupName;
@Id
@Column(name="userId")
private String userId;


@Column(name="groupId")
private String group;


public String getUserId() {
    return userId;
}


public void setUserId(String userId) {
    this.userId = userId;
}


public String getGroup() {
    return group;
}


public void setGroup(String group) {
    this.group = group;
}

public String getServiceProvider() {
    return serviceProvider;
}

public void setServiceProvider(String serviceProvider) {
    this.serviceProvider = serviceProvider;
}

public String getEnterpriseId() {
    return enterpriseId;
}

public void setEnterpriseId(String enterpriseId) {
    this.enterpriseId = enterpriseId;
}

public String getDepartment() {
    return department;
}

public void setDepartment(String department) {
    this.department = department;
}

public String getTrunkGroupName() {
    return trunkGroupName;
}

public void setTrunkGroupName(String trunkGroupName) {
    this.trunkGroupName = trunkGroupName;
}


}

Answer 1

您应该创建一个@Embeddable包含PK字段的新类:

@Embeddable
public class user_groupId implements Serializable { 
    @Column(name="userId")
    private String userId;

    @Column(name="groupId")
    private String group;
}

而在使用它@Entity作为@EmbeddedId:

@Entity
public class user_group {

    @EmbeddedId
    user_groupId id;

    ...
}

您也可以使用@IdClass注释来实现该效果.

Pascal Thivent的这个出色的答案详细阐述了细节.您也可以看看这个其他答案,我前一段时间发布到一个几乎相同的问题.

另外,如果您可以控制数据库结构,也可以考虑避免使用复合键.有一些理由这样做.