Spring Data Neo4j 使用

添加Spring Data Neo4j相关依赖

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-neo4j</artifactId>
</dependency>
<dependency>
    <groupId>org.neo4j</groupId>
    <artifactId>neo4j-ogm-http-driver</artifactId>
</dependency>
<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <optional>true</optional>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-test</artifactId>
    <scope>test</scope>
</dependency>

application.yml添加Neo4j环境配置

spring:
  data:
    neo4j:
      uri: http://localhost:7474
      username: neo4j
      password: 123456

Neo4j中要定义节点，使用Spring Data Neo4j的注解@NodeEntity，标记该类为节点，节点名称为 StudentNode

@Getter
@Setter
@ToString
@NodeEntity
public class StudentNode {
    /**
     * neo4j 生成的id
     */
    @Id
    @GeneratedValue
    private Long id;
    /**
     * 属性，name
     */
    private String name;
    /**
     * 关系，定义为友谊
     */
    @Relationship(type = "FRIENDSHIP_RELATION")
    private List<FriendshipRelation> friendshipRelationList;
    /**
     * 添加友谊的关系
     * @param friendshipRelation
     */
    public void addRelation(FriendshipRelation friendshipRelation){
        if(this.friendshipRelationList == null){
            this.friendshipRelationList = new ArrayList<>();
        }
        this.friendshipRelationList.add(friendshipRelation);
    }
}

Neo4j也要定义关系，使用Spring Data Neo4j的注解@RelationshipEntity，标记其为关系，关系名为 FRIENDSHIP_RELATION，在里面定义StartNode和EndNode

@Getter
@Setter
@Component
@RelationshipEntity(type = "FRIENDSHIP_RELATION")
public class FriendshipRelation {
    @Id
    @GeneratedValue
    private Long id;

    @StartNode
    private StudentNode from;

    @EndNode
    private StudentNode to;
}

StudentNodeRepository为数据库操作，因为后面有删除关系，所以需要@Transactional

@Repository
@Transactional
public interface StudentRepository extends Neo4jRepository<StudentNode,Long> {

    /**
     * 通过name查找学生node
     * @param name
     * @return
     */
    StudentNode findByName(String name);

    /**
     * 根据name获取学生 in 友谊关系
     * @param name
     * @return
     */
    @Query("match " +
            "p=(a:StudentNode) - [r:FRIENDSHIP_RELATION*0..] -> " +
            "(b:StudentNode) " +
            "where b.name = {0} " +
            "return p")
    List<FriendshipRelation> inFriendship(String name);

    /**
     * 根据name获取学生 out 友谊关系
     * @param name
     * @return
     */
    @Query("match " +
            "p=(b:StudentNode) " +
            "- [rr:FRIENDSHIP_RELATION*0..] -> (c:StudentNode) " +
            "where b.name = {0} " +
            "return p")
    List<FriendshipRelation> outFriendship(String name);

    /**
     * 根据name获取学生 both 友谊关系
     * @param name
     * @return
     */
    @Query("match " +
            "p=(a:StudentNode) <- [r:FRIENDSHIP_RELATION*0..] -> " +
            "(b:StudentNode) " +
            "<- [rr:FRIENDSHIP_RELATION*0..] -> (c:StudentNode) " +
            "where b.name = {0} " +
            "return p")
    List<FriendshipRelation> bothFriendship(String name);
}

Neo4jServiceImpl中定义添加关系和删除关系，都需要保存from端的节点关系即可
删除节点时使用了find和save方法，需要添加@Transactional注解

@Service("neo4jServiceImpl")
public class Neo4jServiceImpl implements Neo4jService {

    @Autowired
    private StudentRepository studentRepository;

    @Override
    public void saveFriendship(String fromName, String toName) {
        StudentNode from = studentRepository.findByName(fromName);
        StudentNode to = studentRepository.findByName(toName);

        FriendshipRelation friendshipRelation = new FriendshipRelation();
        friendshipRelation.setFrom(from);
        friendshipRelation.setTo(to);

        //只需要在from节点保存关系即可
        from.addRelation(friendshipRelation);
        studentRepository.save(from);
    }

    //删除节点时，使用find，save 需要@Transactional注解
    @Transactional(rollbackFor = Exception.class)
    @Override
    public void deleteFriendship(String fromName, String toName) {
        StudentNode fromStudentNode = studentRepository.findByName(fromName);
        List<FriendshipRelation> friendshipRelationList = fromStudentNode.getFriendshipRelationList();
        for (Iterator<FriendshipRelation> iterator = friendshipRelationList.iterator(); iterator.hasNext();) {
            FriendshipRelation relation = iterator.next();
            StudentNode fromNode = relation.getFrom();
            StudentNode toNode = relation.getTo();

            String fromNodeName = fromNode.getName();
            String toNodeName = toNode.getName();
            //判断 fromName 和 toName 需要删除的关系是否相等
            if(fromNodeName.equals(fromName) && toNodeName.equals(toName)){
                iterator.remove();
            }
        }
        //只需要在from节点保存关系即可
        studentRepository.save(fromStudentNode);
    }
}

Neo4jTest进行测试，均可成功

@RunWith(SpringRunner.class)
@SpringBootTest
public class Neo4jTest {
    @Autowired
    private StudentRepository studentRepository;

    @Autowired
    private Neo4jService neo4jService;

    /**
     * 保存单个节点
     */
    @Test
    public void saveStudentNode(){
        StudentNode studentNode = new StudentNode();
        studentNode.setName("张0");
        studentRepository.save(studentNode);
    }

    /**
     * 通过name查询学生节点
     */
    @Test
    public void findStudentNodeByName(){
        StudentNode studentNode = studentRepository.findByName("张0");
        System.out.println("");
    }

    /**
     * 保存批量节点
     */
    @Test
    public void saveAllStudentNode(){
        List<StudentNode> studentNodeList = new ArrayList<>();
        StudentNode studentNode;
        for(int i = 1; i <= 10; i++){
            studentNode = new StudentNode();
            studentNode.setName("张" + i);
            studentNodeList.add(studentNode);
        }
        studentRepository.saveAll(studentNodeList);
    }

    /**
     * 查询全部
     */
    @Test
    public void findAll(){
        //iterable to list
        List<StudentNode> studentNodeList = Lists.newArrayList(studentRepository.findAll());
        System.out.println("");
    }

    /**
     * 分页查询
     */
    @Test
    public void pageFindAll(){
        Pageable pageable = PageRequest.of(0,2);
        Page<StudentNode> studentNodePage = studentRepository.findAll(pageable);
        System.out.println("");
    }

    /**
     * 保存如下友谊关系
     *
     * 1 <-> 2 <-> 5 -> 9
     *          -> 6
     *    -> 3 <-> 7 -> 10
     *    -> 4 <-> 8
     */
    @Test
    public void saveFriendship(){
        neo4jService.saveFriendship("张1","张2");
        neo4jService.saveFriendship("张1","张3");
        neo4jService.saveFriendship("张1","张4");

        neo4jService.saveFriendship("张2","张1");
        neo4jService.saveFriendship("张2","张5");
        neo4jService.saveFriendship("张2","张6");

        neo4jService.saveFriendship("张3","张7");

        neo4jService.saveFriendship("张4","张8");

        neo4jService.saveFriendship("张5","张2");
        neo4jService.saveFriendship("张5","张9");

        neo4jService.saveFriendship("张7","张3");
        neo4jService.saveFriendship("张7","张10");

        neo4jService.saveFriendship("张8","张4");
    }

    /**
     * 根据name查询 both 友谊关系
     */
    @Test
    public void getBothFriendship(){
        List<FriendshipRelation> friendshipRelationList1 = studentRepository.bothFriendship("张1");
    }

    /**
     * 根据name查询 in 友谊关系
     */
    @Test
    public void getInFriendship(){
        List<FriendshipRelation> friendshipRelationList1 = studentRepository.inFriendship("张1");
    }

    /**
     * 根据name查询 out 友谊关系
     */
    @Test
    public void getOutFriendship(){
        List<FriendshipRelation> friendshipRelationList1 = studentRepository.outFriendship("张1");
    }

    /**
     * 删除 1 -> 3 友谊关系
     */
    @Test
    public void deleteFriendship(){
        neo4jService.deleteFriendship("张1","张3");
    }
}

保存单节点 张0
保存多节点 张1~张10
保存 张1~张10 友谊关系
删除 张1 和 张3 关系