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優(yōu)質文章，第一時間送達

1.NEO4J簡介

NEO4J，NoSql家族中的一員，最早發(fā)行的圖形數(shù)據(jù)庫，目前依然是主流圖形數(shù)據(jù)庫。優(yōu)點是：圖論的數(shù)據(jù)庫實現(xiàn)，對各種圖算法做了簡易封裝，使開發(fā)者不再關注于算法的具體實現(xiàn)，可以集中精力于業(yè)務的實現(xiàn)。采用java編寫，社區(qū)版開源，企業(yè)版閉源。

2.傳統(tǒng)關系型數(shù)據(jù)庫與圖形數(shù)據(jù)庫的糾葛

上世紀軟硬件的限制使oracle\mysql等一大批數(shù)據(jù)庫應運而生，建立在集合論基礎上實現(xiàn)的數(shù)據(jù)庫，通過外鍵理論在實際上勉強完成了簡單的關系。而最早的NEO4J等圖形數(shù)據(jù)庫還在開發(fā)者的肚子里，關系型數(shù)據(jù)庫之名就這樣被搶走了。

3.怎么把neo4j怎么集成到我們的程序中？

場景：A同學被老大安排開發(fā)一個關于社交關系的需求，根據(jù)A同學多年的開發(fā)經驗，mysql是肯定做不了的（因為關系型數(shù)據(jù)庫的數(shù)學基礎是集合論，依靠外鍵來實現(xiàn)簡單的關系，對于深層關系的查詢遞歸將會慢到一個讓人無法接受的程度）。百度一下，NEO4J——以圖論為基礎的數(shù)據(jù)庫，就它了。開始百度怎么往項目中集成NEO4J，A同學發(fā)現(xiàn)一個看上去不錯的demo，這么多人轉發(fā)and不要臉的抄襲，應該不錯，上去鼓搗一陣，最后發(fā)現(xiàn)：咦？怎么報錯了，一模一樣的啊；臥槽，這錘子不發(fā)maven依賴，版本用的不對啊......幾小時就這么浪費了，還打擊了自己的信心。

引入的方法有很多種，但是spring提供的辦法絕對是最簡單方便的。怎么看？當然是看官網提供的15min的案例，地址：https://spring.io/guides/gs/accessing-data-neo4j/。怎么找，看下面的截圖。

4.集成步驟截圖：

前置條件

1.電腦已正確安裝maven、jdk、Eclipse|IDEA

（1）下載neo4j的window解壓包。地址：https://neo4j.com/，下載下來的解壓包如下：

（2）配置NEO4J_HOME的環(huán)境變量。

（3）安裝neo4J的服務

cmd命令：

1.neo4j install-service
2.neo4j start

假如neo4j服務安裝失敗，也可以用以下命令啟動：

neo4j.bat console

查看http://localhost:7474/browser/，賬號和密碼都是:neo4j，然后修改密碼，進入如下頁面：

（4）springboot集成neo4j，對比官網demo，下面就放我自己的代碼上來：

1.pom.xml

"1.0"?encoding="UTF-8"?>
"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">
????4.0.0
????
????????org.springframework.boot
????????spring-boot-starter-parent
????????2.3.2.RELEASE
?????????
????
????com.example
????neo4j
????0.0.1-SNAPSHOT
????neo4j
????Demo?project?for?Spring?neo4j
?
????
????????1.8
????
?
????
????????
????????????org.springframework.boot
????????????spring-boot-starter-data-neo4j
????????
?
????????
????????????org.springframework.boot
????????????spring-boot-starter-test
????????????test
????????????
????????????????
????????????????????org.junit.vintage
????????????????????junit-vintage-engine
????????????????
????????????
????????
????
?
????
????????
????????????
????????????????org.springframework.boot
????????????????spring-boot-maven-plugin
????????????
????????
????
?

2.application.properties

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

3.Person實體類

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?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層調用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?findByName(String?name);
?
????List?findByTeammatesName(String?name);
?
????@Query(value?=?"match?(Greg:Person)?return?Greg",
????????????countQuery=?"match?(Greg:Person)?return?count(Greg)")
????Page?getActorsThatActInAmoviesFromTitle(?Pageable?pageable?);
?
????@Query(value?="",countQuery?=?"")
????List?getAllById();
}

5.springboot啟動類

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?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?teammates?=?personRepository.findByTeammatesName(greg.getName());
????????????log.info("The?following?have?Greg?as?a?teammate...");
????????????teammates.stream().forEach(person?->?log.info("\t"?+?person.getName()));
????????????Page?grag=personRepository.getActorsThatActInAmoviesFromTitle(PageRequest.of(0,5));
????????????log.info("\t"?+?grag);
????????};
????}
?
}

6.啟動截圖

7.在neo4j控制臺查詢結果：

本文鏈接：

https://blog.csdn.net/a__da/article/details/112484242

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