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前言

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图形数据库是专门用于存储图形数据的数据库，它使用图形模型来存储数据，并且支持复杂的图形查询。常见的图形数据库有Neo4j、OrientDB等。

Neo4j是用Java实现的开源NoSQL图数据库，本篇博客介绍如何在SpringBoot中使用Neo4j图数据库，如何进行简单的增删改查，以及如何进行复杂的查询。

本篇博客相关代码的git网址如下：

https://gitee.com/pet365/spring-boot-neo4j

关于Neo4j的博客文章如下：

• 图数据库Neo4j——Neo4j简介、数据结构 & Docker版本的部署安装 & Cypher语句的入门

引出

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1.Neo4j是用Java实现的开源NoSQL图数据库;
2.SpringBoot使用Neo4j，继承Neo4jRepository进行简单增删改查；
3.使用Neo4jClient进行复杂的查询；

springBoot整合

1、引入依赖

<!--        neo4j的包--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-neo4j</artifactId></dependency>

2、配置文件

server:port: 9902
logging:level:org.springframework.data.neo4j: debug
spring:application:name: spring-neo4jdata:neo4j:database: neo4jneo4j:authentication:username: neo4jpassword: neo4j123uri: neo4j://192.168.150.101:7687

3、实体类定义

提取抽象类

不同的节点类，网点、一级转运中心、二级转运中心

4、dao继承Neo4jRepository

进行自定义查询：

Keyword	Sample	Cypher snippet
After	findByLaunchDateAfter(Date date)	n.launchDate > date
Before	findByLaunchDateBefore(Date date)	n.launchDate < date
Containing (String)	findByNameContaining(String namePart)	n.name CONTAINS namePart
Containing (Collection)	findByEmailAddressesContains(Collection addresses) findByEmailAddressesContains(String address)	ANY(collectionFields IN [addresses] WHERE collectionFields in n.emailAddresses) ANY(collectionFields IN address WHERE collectionFields in n.emailAddresses)
In	findByNameIn(Iterable names)	n.name IN names
Between	findByScoreBetween(double min, double max) findByScoreBetween(Range range)	n.score >= min AND n.score <= max Depending on the Range definition n.score >= min AND n.score <= max or n.score > min AND n.score < max
StartingWith	findByNameStartingWith(String nameStart)	n.name STARTS WITH nameStart
EndingWith	findByNameEndingWith(String nameEnd)	n.name ENDS WITH nameEnd
Exists	findByNameExists()	EXISTS(n.name)
True	findByActivatedIsTrue()	n.activated = true
False	findByActivatedIsFalse()	NOT(n.activated = true)
Is	findByNameIs(String name)	n.name = name
NotNull	findByNameNotNull()	NOT(n.name IS NULL)
Null	findByNameNull()	n.name IS NULL
GreaterThan	findByScoreGreaterThan(double score)	n.score > score
GreaterThanEqual	findByScoreGreaterThanEqual(double score)	n.score >= score
LessThan	findByScoreLessThan(double score)	n.score < score
LessThanEqual	findByScoreLessThanEqual(double score)	n.score <= score
Like	findByNameLike(String name)	n.name =~ name
NotLike	findByNameNotLike(String name)	NOT(n.name =~ name)
Near	findByLocationNear(Distance distance, Point point)	distance( point(n),point({latitude:lat, longitude:lon}) ) < distance
Regex	findByNameRegex(String regex)	n.name =~ regex
And	findByNameAndDescription(String name, String description)	n.name = name AND n.description = description
Or	findByNameOrDescription(String name, String description)	n.name = name OR n.description = description (Cannot be used to OR nested properties)

package com.tianju.mapper;import com.tianju.entity.AgencyEntity;
import org.mapstruct.Mapper;
import org.springframework.data.neo4j.repository.Neo4jRepository;/*** 网点的mapper，比如菜鸟驿站*/
@Mapper
public interface AgencyMapper extends Neo4jRepository<AgencyEntity,Long> {/*** 根据bid 查询* @param bid 业务id* @return 网点数据*/AgencyEntity findByBid(Long bid);/*** 根据bid删除** @param bid 业务id* @return 删除的数据条数*/Long deleteByBid(Long bid);
}

复杂查询

最短路径查询

//查询两个网点之间最短路径，查询深度最大为10
MATCH path = shortestPath((n:AGENCY) -[*..10]->(m:AGENCY))WHERE n.name = "北京市昌平区定泗路" AND m.name = "上海市浦东新区南汇"RETURN path

package com.tianju.mapper.impl;import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.collection.CollUtil;
import cn.hutool.core.map.MapUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.db.meta.Column;
import com.tianju.dto.OrganDTO;
import com.tianju.dto.TransportLineNodeDTO;
import com.tianju.entity.AgencyEntity;
import com.tianju.enums.OrganTypeEnum;
import com.tianju.mapper.TransportLineRepository;
import org.neo4j.driver.internal.InternalPoint2D;
import org.neo4j.driver.types.Path;
import org.neo4j.driver.types.Relationship;
import org.springframework.data.neo4j.core.schema.Node;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.neo4j.core.Neo4jClient;
import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
import org.springframework.stereotype.Component;import java.util.Map;
import java.util.Optional;@Component
public class TransportLineRepositoryImpl implements TransportLineRepository {@Autowiredprivate Neo4jClient neo4jClient;/*** 查询最短路线* @param start 开始网点* @param end   结束网点* @return*/@Overridepublic TransportLineNodeDTO findShortestPath(AgencyEntity start, AgencyEntity end) {// 获取网点数据在Neo4j中的类型 @Node("AGENCY") @Node("OLT")String type = AgencyEntity.class.getAnnotation(Node.class).value()[0];// 构造Sql语句 $startId
//        String cql = "MATCH path = shortestPath((n:AGENCY) -[*..10]->(m:AGENCY))\n" +
//                "WHERE n.bid = $startId AND m.bid = $endId\n" +
//                "RETURN path";String cql = StrUtil.format("MATCH path = shortestPath((n:{}) -[*..10]->(m:{})) " +"WHERE n.bid = $startId AND m.bid = $endId " +"RETURN path",type,type);// 执行自定义查询Neo4jClient.RecordFetchSpec<TransportLineNodeDTO> recordFetchSpec = neo4jClient.query(cql).bind(start.getBid()).to("startId") // 替换 $startId.bind(end.getBid()).to("endId")  // 替换 $endId.fetchAs(TransportLineNodeDTO.class)   // 设置响应类型，指定为 TransportLineNodeDTO 类型.mappedBy((typeSystem, record) -> {    // 设置结果集映射Path path = record.get(0).asPath();// 得到第一条路线TransportLineNodeDTO transportLineNodeDTO = new TransportLineNodeDTO();path.nodes().forEach(node -> { // 将每个节点信息封装成一个 OrganDto// 获得节点的 键值对 address: 上海市转运中心；bid：8002Map<String, Object> map = node.asMap();// {name=北京市昌平区定泗路,// location=Point{srid=4326, x=116.37212849638287, y=40.11765281246394},// address=北七家镇定泗路苍龙街交叉口, bid=100280, phone=010-86392987}System.out.println("map: "+map);// 把键值对转换成对象 OrganDTOOrganDTO organDTO = BeanUtil.toBeanIgnoreError(map, OrganDTO.class);// organDTO:// OrganDTO(id=100280, name=北京市昌平区定泗路, type=null, phone=010-86392987,// address=北七家镇定泗路苍龙街交叉口, latitude=null, longitude=null)// type,latitude,longitude 没有映射成功System.out.println("organDTO: "+organDTO);// 获得标签的名称 OLT,TLT,String first = CollUtil.getFirst(node.labels());// 根据OLT获得枚举类型 OLT(1, "一级转运中心"),OrganTypeEnum organTypeEnum = OrganTypeEnum.valueOf(first);// 再获得枚举类型的 code ：1、2、3organDTO.setType(organTypeEnum.getCode()); // 设置类型的映射// 经纬度 "location": point({srid:4326, x:121.59815370294322, y:31.132409729356993})InternalPoint2D location = MapUtil.get(map, "location", InternalPoint2D.class); // 经纬度 BeanUtil.getProperty(map.get("location"),"x");organDTO.setLatitude(location.x());  // 设置经纬度映射organDTO.setLongitude(location.y()); // 经纬度映射// OrganDTO(id=100280, name=北京市昌平区定泗路, type=3,// phone=010-86392987, address=北七家镇定泗路苍龙街交叉口,// latitude=116.37212849638287, longitude=40.11765281246394)System.out.println("organDTO: "+organDTO);transportLineNodeDTO.getNodeList().add(organDTO);});System.out.println("transportLineNodeDTO: "+transportLineNodeDTO);path.relationships().forEach(relationship -> {// 路径下面的关系Map<String, Object> map = relationship.asMap();Double cost = MapUtil.get(map, "cost", Double.class);transportLineNodeDTO.setCost(cost + transportLineNodeDTO.getCost());});System.out.println("transportLineNodeDTO: "+transportLineNodeDTO);return transportLineNodeDTO;});Optional<TransportLineNodeDTO> one = recordFetchSpec.one(); // Optional，1.8提供的，可以处理null的情况return one.orElse(null); // 如果为null，就返回null，如果不是null，就返回结果}
}

最小成本查询

package com.tianju.mapper.impl;import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.collection.CollUtil;
import cn.hutool.core.map.MapUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.db.meta.Column;
import com.tianju.dto.OrganDTO;
import com.tianju.dto.TransportLineNodeDTO;
import com.tianju.entity.AgencyEntity;
import com.tianju.enums.OrganTypeEnum;
import com.tianju.mapper.TransportLineRepository;
import org.neo4j.driver.internal.InternalPoint2D;
import org.neo4j.driver.types.Path;
import org.neo4j.driver.types.Relationship;
import org.springframework.data.neo4j.core.schema.Node;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.neo4j.core.Neo4jClient;
import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
import org.springframework.stereotype.Component;import java.util.Map;
import java.util.Optional;@Component
public class TransportLineRepositoryImpl implements TransportLineRepository {@Autowiredprivate Neo4jClient neo4jClient;@Overridepublic TransportLineNodeDTO findCostLeastPath(AgencyEntity start, AgencyEntity end) {String type = AgencyEntity.class.getAnnotation(Node.class).value()[0];String cqlB = "MATCH path = (n:{}) -[*..10]->(m:{}) " +"WHERE n.bid = $startId AND m.bid = $endId " +"UNWIND relationships(path) AS r " +"WITH sum(r.cost) AS cost, path " +"RETURN path ORDER BY cost ASC, LENGTH(path) ASC LIMIT 1";String cql = StrUtil.format(cqlB, type,type);Optional<TransportLineNodeDTO> one = neo4jClient.query(cql).bind(start.getBid()).to("startId").bind(end.getBid()).to("endId").fetchAs(TransportLineNodeDTO.class).mappedBy(((typeSystem, record) -> {Path path = record.get(0).asPath();TransportLineNodeDTO transportLineNodeDTO = new TransportLineNodeDTO();path.nodes().forEach(node -> {Map<String, Object> map = node.asMap();OrganDTO organDTO = BeanUtil.toBeanIgnoreError(map, OrganDTO.class);// 获得标签的名称 OLT,TLT,String first = CollUtil.getFirst(node.labels());// 根据OLT获得枚举类型 OLT(1, "一级转运中心"),OrganTypeEnum organTypeEnum = OrganTypeEnum.valueOf(first);// 再获得枚举类型的 code ：1、2、3organDTO.setType(organTypeEnum.getCode()); // 设置类型的映射// 经纬度 "location": point({srid:4326, x:121.59815370294322, y:31.132409729356993})InternalPoint2D location = MapUtil.get(map, "location", InternalPoint2D.class); // 经纬度 BeanUtil.getProperty(map.get("location"),"x");organDTO.setLatitude(location.x());  // 设置经纬度映射organDTO.setLongitude(location.y()); // 经纬度映射transportLineNodeDTO.getNodeList().add(organDTO);});path.relationships().forEach(relationship -> {// 路径下面的关系Map<String, Object> map = relationship.asMap();Double cost = MapUtil.get(map, "cost", Double.class);transportLineNodeDTO.setCost(cost + transportLineNodeDTO.getCost());});return transportLineNodeDTO;})).one();return one.orElse(null);}private void findShortestPathMy(){String cql = "MATCH path = shortestPath((n:AGENCY) -[*..10]->(m:AGENCY)) " +"WHERE n.bid = 210127 AND m.bid = 100260 " +"RETURN path";// 执行自定义查询Neo4jClient.UnboundRunnableSpec query = neo4jClient.query(cql);ThreadPoolTaskExecutor threadPoolTaskExecutor = new ThreadPoolTaskExecutor();}
}

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总结

1.Neo4j是用Java实现的开源NoSQL图数据库;
2.SpringBoot使用Neo4j，继承Neo4jRepository进行简单增删改查；
3.使用Neo4jClient进行复杂的查询；