springboot集成neo4j - HelloWorld开发者社区

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1.NEO4J简介

NEO4J，NoSql家族中的一员，最早发行的图形数据库，目前依然是主流图形数据库。优点是：图论的数据库实现，对各种图算法做了简易封装，使开发者不再关注于算法的具体实现，可以集中精力于业务的实现。采用java编写，社区版开源，企业版闭源。

2.传统关系型数据库与图形数据库的纠葛

上世纪软硬件的限制使oracle\mysql等一大批数据库应运而生，建立在集合论基础上实现的数据库，通过外键理论在实际上勉强完成了简单的关系。而最早的NEO4J等图形数据库还在开发者的肚子里，关系型数据库之名就这样被抢走了。

3.怎么把neo4j怎么集成到我们的程序中？

场景：A同学被老大安排开发一个关于社交关系的需求，根据A同学多年的开发经验，mysql是肯定做不了的（因为关系型数据库的数学基础是集合论，依靠外键来实现简单的关系，对于深层关系的查询递归将会慢到一个让人无法接受的程度）。百度一下，NEO4J——以图论为基础的数据库，就它了。开始百度怎么往项目中集成NEO4J，A同学发现一个看上去不错的demo，这么多人转发and不要脸的抄袭，应该不错，上去鼓捣一阵，最后发现：咦？怎么报错了，一模一样的啊；卧槽，这锤子不发maven依赖，版本用的不对啊......几小时就这么浪费了，还打击了自己的信心。

引入的方法有很多种，但是spring提供的办法绝对是最简单方便的。怎么看？当然是看官网提供的15min的案例，地址：https://spring.io/guides/gs/accessing-data-neo4j/。怎么找，看下面的截图。

springboot集成neo4j

4.集成步骤截图：

前置条件

1.电脑已正确安装maven、jdk、Eclipse|IDEA

（1）下载neo4j的window解压包。地址：https://neo4j.com/，下载下来的解压包如下：

springboot集成neo4j

（2）配置NEO4J_HOME的环境变量。

springboot集成neo4j

（3）安装neo4J的服务

cmd命令：

1.neo4j install-service

2.neo4j start

springboot集成neo4j

假如neo4j服务安装失败，也可以用以下命令启动：

neo4j.bat console

springboot集成neo4j

查看http://localhost:7474/browser/，账号和密码都是:neo4j，然后修改密码，进入如下页面：

springboot集成neo4j

（4）springboot集成neo4j，对比官网demo，下面就放我自己的代码上来：

1.pom.xml

<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.3.2.RELEASE</version> <relativePath/>  </parent> <groupId>com.example</groupId> <artifactId>neo4j</artifactId> <version>0.0.1-SNAPSHOT</version> <name>neo4j</name> <description>Demo project for Spring neo4j</description> <properties> <java.version>1.8</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-neo4j</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> <exclusions> <exclusion> <groupId>org.junit.vintage</groupId> <artifactId>junit-vintage-engine</artifactId> </exclusion> </exclusions> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project>

2.application.properties

spring.data.neo4j.uri=bolt://localhost:7687 spring.data.neo4j.username=neo4j spring.data.neo4j.password=neo4j

3.Person实体类

package com.example.neo4j.entity; import java.util.Collections; import java.util.HashSet; import java.util.Optional; import java.util.Set; import java.util.stream.Collectors; import org.neo4j.ogm.annotation.GeneratedValue; import org.neo4j.ogm.annotation.Id; import org.neo4j.ogm.annotation.NodeEntity; import org.neo4j.ogm.annotation.Relationship; @NodeEntity public class Person { @Id @GeneratedValue private Long id; private String name; 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 = "TEAMMATE", direction = Relationship.UNDIRECTED) public Set<Person> teammates; public void worksWith(Person person) { if (teammates == null) { teammates = new HashSet<>(); } teammates.add(person); } public String toString() { return this.name + "'s teammates => " + Optional.ofNullable(this.teammates).orElse( Collections.emptySet()).stream() .map(Person::getName) .collect(Collectors.toList()); } public String getName() { return name; } public void setName(String name) { this.name = name; } }

4.dao层调用neo4j，jpa的方式：

package com.example.neo4j.repository; import java.util.List; import com.example.neo4j.entity.Person; import org.springframework.data.domain.Page; import org.springframework.data.domain.Pageable; import org.springframework.data.neo4j.annotation.Query; import org.springframework.data.neo4j.repository.Neo4jRepository; public interface PersonRepository extends Neo4jRepository<Person, Long> { Person findByName(String name); List<Person> findByTeammatesName(String name); @Query(value = "match (Greg:Person) return Greg", countQuery= "match (Greg:Person) return count(Greg)") Page<Person> getActorsThatActInAmoviesFromTitle( Pageable pageable ); @Query(value ="",countQuery = "") List<Person> getAllById(); }

5.springboot启动类

package com.example.neo4j; import com.example.neo4j.entity.Person; import com.example.neo4j.repository.PersonRepository; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.boot.CommandLineRunner; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.context.annotation.Bean; import org.springframework.data.domain.Page; import org.springframework.data.domain.PageRequest; import org.springframework.data.neo4j.repository.config.EnableNeo4jRepositories; import java.util.Arrays; import java.util.List; @SpringBootApplication @EnableNeo4jRepositories public class Neo4jApplication { private final static Logger log = LoggerFactory.getLogger(Neo4jApplication.class); public static void main(String[] args) { SpringApplication.run(Neo4jApplication.class, args); System.exit(0); } @Bean CommandLineRunner demo(PersonRepository personRepository) { return args -> { personRepository.deleteAll(); Person greg = new Person("Greg"); Person roy = new Person("Roy"); Person craig = new Person("Craig"); List<Person> team = Arrays.asList(greg, roy, craig); log.info("Before linking up with Neo4j..."); team.stream().forEach(person -> log.info("\t" + person.toString())); personRepository.save(greg); personRepository.save(roy); personRepository.save(craig); greg = personRepository.findByName(greg.getName()); greg.worksWith(roy); greg.worksWith(craig); personRepository.save(greg); roy = personRepository.findByName(roy.getName()); roy.worksWith(craig); // We already know that roy works with greg personRepository.save(roy); // We already know craig works with roy and greg log.info("Lookup each person by name..."); team.stream().forEach(person -> log.info( "\t" + personRepository.findByName(person.getName()).toString())); List<Person> teammates = personRepository.findByTeammatesName(greg.getName()); log.info("The following have Greg as a teammate..."); teammates.stream().forEach(person -> log.info("\t" + person.getName())); Page<Person> grag=personRepository.getActorsThatActInAmoviesFromTitle(PageRequest.of(0,5)); log.info("\t" + grag); }; } }

6.启动截图

springboot集成neo4j