Spring Data JPA 联合主键

言曌 2018年04月24日21:44:44 6 5033 views

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比如我们这里想要创建一张表，用于用户关注和粉丝。

relationship 两个字段，都是主键（即联合主键）

Spring Data JPA 实体如何设计才能自动创建这样的表呢？

仅仅使用两个 @Id 吗？

答案不是。

解决办法

实体

Relationship.java 实体

package com.liuyanzhao.forum.entity;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.IdClass;
/**
* @author 言曌
* @date 2018/4/24 下午9:38
*/
@Entity
@IdClass(RelationshipPK.class)
public class Relationship {
private Long fromUserId;
private Long toUserId;
@Id
@Column(name = "from_user_id", nullable = false)
public Long getFromUserId() {
return fromUserId;
}
public void setFromUserId(Long fromUserId) {
this.fromUserId = fromUserId;
}
@Id
@Column(name = "to_user_id", nullable = false)
public Long getToUserId() {
return toUserId;
}
public void setToUserId(Long toUserId) {
this.toUserId = toUserId;
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Relationship that = (Relationship) o;
if (fromUserId != null ? !fromUserId.equals(that.fromUserId) : that.fromUserId != null) return false;
if (toUserId != null ? !toUserId.equals(that.toUserId) : that.toUserId != null) return false;
return true;
}
@Override
public int hashCode() {
int result = fromUserId != null ? fromUserId.hashCode() : 0;
result = 31 * result + (toUserId != null ? toUserId.hashCode() : 0);
return result;
}
}

RelationshipPK.java 辅助

package com.liuyanzhao.forum.entity;
import javax.persistence.Column;
import javax.persistence.Id;
import java.io.Serializable;
/**
* @author 言曌
* @date 2018/4/24 下午9:38
*/
public class RelationshipPK implements Serializable {
private Long fromUserId;
private Long toUserId;
@Column(name = "from_user_id", nullable = false)
@Id
public Long getFromUserId() {
return fromUserId;
}
public void setFromUserId(Long fromUserId) {
this.fromUserId = fromUserId;
}
@Column(name = "to_user_id", nullable = false)
@Id
public Long getToUserId() {
return toUserId;
}
public void setToUserId(Long toUserId) {
this.toUserId = toUserId;
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
RelationshipPK that = (RelationshipPK) o;
if (fromUserId != null ? !fromUserId.equals(that.fromUserId) : that.fromUserId != null) return false;
if (toUserId != null ? !toUserId.equals(that.toUserId) : that.toUserId != null) return false;
return true;
}
@Override
public int hashCode() {
int result = fromUserId != null ? fromUserId.hashCode() : 0;
result = 31 * result + (toUserId != null ? toUserId.hashCode() : 0);
return result;
}
}

启动项目，生成的数据表符合要求

RelationshipRepository.java

package com.liuyanzhao.forum.repository;
import com.liuyanzhao.forum.entity.Relationship;
import com.liuyanzhao.forum.entity.RelationshipPK;
import org.springframework.data.jpa.repository.JpaRepository;
import java.util.List;
/**
* @author 言曌
* @date 2018/4/24 下午9:47
*/
public interface RelationshipRepository extends JpaRepository<Relationship, RelationshipPK> {
/**
* 根据关注者id查找所有记录（查找关注的人的id）
*
* @param fromUserId
* @return
*/
List<Relationship> findByFromUserId(Long fromUserId);
/**
* 根据被关注者查找所有记录（查找粉丝的id）
*
* @param toUserId
* @return
*/
List<Relationship> findByToUserId(Long toUserId);
/**
* 根据关注者和被关注者id查找某条记录
* @param fromUserId
* @param toUserId
* @return
*/
Relationship findByFromUserIdAndToUserId(Long fromUserId, Long toUserId);
}

package com.liuyanzhao.forum.repository;
import com.liuyanzhao.forum.entity.Relationship;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;
import java.util.List;
import static org.junit.Assert.*;
/**
* @author 言曌
* @date 2018/4/24 下午9:56
*/
@SpringBootTest
@RunWith(SpringRunner.class)
public class RelationshipRepositoryTest {
@Autowired
private RelationshipRepository relationshipRepository;
@Test
public void save() {
relationshipRepository.save(new Relationship(1L,2L));
relationshipRepository.save(new Relationship(1L,3L));
relationshipRepository.save(new Relationship(1L,4L));
relationshipRepository.save(new Relationship(2L,3L));
relationshipRepository.save(new Relationship(2L,4L));
relationshipRepository.save(new Relationship(3L,4L));
}
@Test
public void findByFromUserId() throws Exception {
List<Relationship> relationshipList = relationshipRepository.findByFromUserId(1L);
System.out.println(relationshipList);
}
@Test
public void findByToUserId() throws Exception {
List<Relationship> relationshipList = relationshipRepository.findByToUserId(4L);
System.out.println(relationshipList);
}
@Test
public void findByFromUserIdAndToUserId() throws Exception {
Relationship relationship = relationshipRepository.findByFromUserIdAndToUserId(1L,2L);
System.out.println();
}
}

四月

24日