【干货】一文搞懂java+neo4j

一.neo4j安装

1.安装jdk，这个就不讲了，版本为1.8

2.安装neo4j

官网：https://neo4j.com/download-center/

区分为社区版和企业版（收费）区别如下：

 

注意：4.X版本需要对应java11以上，所以我们选择3.5 

下载完毕后解压，进入conf目录，修改配置文件

"dbms.default_listen_address=0.0.0.0"取消注释

然后进入bin目录，运行./neo4j start

启动后访问http://<ip>:7474/browser/

 二.neo4j的sql语法

举些简单例子：

查询老李的所有相关属性： MATCH (n)-[r*1..]->(m) where n.name='老李' return n,r,m

查询所有张三的同事关系:  match (n)-[r:`同事`]-(m) where n.name='张三' return m,n,r;

查询老李的所有同事的相关属性: match(n)-[r:`同事`]-(q)-[b]-(m) where n.name='老李' return n,m,r,b,q
 

三.java实战neo4j

引入neo4j依赖：

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-neo4j</artifactId>
    <version>2.5.8</version>
</dependency>
<dependency>
    <groupId>org.neo4j</groupId>
    <artifactId>neo4j-ogm-http-driver</artifactId>
    <version>3.2.1</version>
</dependency>

编写实体类

package com.zjlab.leqing.entity;

import lombok.Data;
import org.springframework.data.neo4j.core.schema.GeneratedValue;
import org.springframework.data.neo4j.core.schema.Id;
import org.springframework.data.neo4j.core.schema.Node;
import org.springframework.data.neo4j.core.schema.Relationship;

import java.util.HashSet;
import java.util.Objects;
import java.util.Set;

/**
 * @author bing.bai
 * @create 2022/7/4
 */
@Node
@Data
public class Person {
    @Id
    @GeneratedValue
    private Long id;

    private String name;

    private String sex;

    private Person() {
        // Empty constructor required as of Neo4j API 2.0.5
    }



    public Person(String name) {
        this.name = name;
    }

    /**
     * Neo4j doesn't REALLY have bi-directional relationships. It just means when querying
     * to ignore the direction of the relationship.
     * https://dzone.com/articles/modelling-data-neo4j
     */
    @Relationship(type = "房产")
    public Set<House> houses;

    @Relationship(type = "车")
    public Set<Car> cars;

    @Relationship(type = "同事")
    public Set<Person> associates;

    public void haveHouse(House house) {
        if (houses == null) {
            houses = new HashSet<>();
        }
        houses.add(house);
    }

    public void haveCar(Car car) {
        if (cars == null) {
            cars = new HashSet<>();
        }
        cars.add(car);
    }

    public void workWith(Person person) {
        if (associates == null) {
            associates = new HashSet<>();
        }
        associates.add(person);
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Person person = (Person) o;
        return Objects.equals(id, person.id) && Objects.equals(name, person.name) && Objects.equals(sex, person.sex) && Objects.equals(houses, person.houses) && Objects.equals(cars, person.cars) && Objects.equals(associates, person.associates);
    }

    @Override
    public int hashCode() {
        return Objects.hash(id);
    }
}

编写mapper：

package com.zjlab.leqing.mapper;

import com.zjlab.leqing.entity.Person;
import org.springframework.data.neo4j.repository.Neo4jRepository;
import org.springframework.data.neo4j.repository.query.Query;

import java.util.List;

/**
 * @author bing.bai
 * @create 2022/7/4
 */
public interface PersonRepository extends Neo4jRepository<Person, Long> {

   List<Person> findByNameIsLike(String name);

   @Query("match (n:House)<-[r:`房产`]-(m:Person) where n.address contains {address} return m,n,r;")
   Person findByHouseAddress(String address);

   @Query("MATCH (n)-[r*1..]->(m) where n.name contains {name} return n,r,m")
   List<Person> findAllByName(String name);
}

启动类增加注解：

编写controller：

最终结果：