Neo4j是一种开源的NoSQL图数据库,将数据以图(把一个个实体当作节点,连接节点的边表示节点间的关系)的形式保存,Neo4j也支持ACID事务管理。关系型数据库数据访问采用的是ORM(对象关系映射),而Neo4j数据库采用的是OGM(对象图形映射, Object Graph Mapper )。

与SDN相匹配的jar包版本

使用Spring Data Neo4j 4.2.x版的需求:

JDK1.8及以上版本

Neo4j Graph DataBase 2.3.x及以上版本

Spring Framework 4.3.9RELEASE及以上版本

使用OGM时确保版本在2.1.1+RELEASE

Spring Data Neo4j 4.2及以后的版本的配置,更加简便。不需要在配置类中继承Neo4jConfiguration,也不需要定义SessionBean。而是定义SessionFactory和Neo4jTransactionManager的对象bean。连接Neo4j时,SDN创建session(org.neo4j.ogm.session.Session)实例时,需要声明SessionFactory.当SessionFactory被创建,它设置了OGM的元数据,使用它来创建所有的Session,同时packages to scan for domain object 元数据需要提供给SessionFactory的构造函数。,@EnableTransactionManagement是用来申明Neo4jTransactionManager的,配置SDN的事物,配置SessionFactory Bean是为了申明OGM的配置,如下图:

使用JPA代理实现repository的config

声明一个Spring Data JPA的依赖

neo4j应用

neo4j的driver有三种:Embedd(内嵌式),HTTP以及二进制协议Bolt

OGM(Object Graph Mapper)neo4j数据库的节点与java实体建立映射关系

SDN在顶端为OGM提供语法以及代码,建立基于Spring的Neo4j/OGM的应用

spring-data-neo4j

<dependency>

<groupId>org.springframework.data</groupId>

<artifactId>spring-data-neo4j</artifactId>

<version>{version}</version>

</dependency>

添加dirver的依赖,三种:embedded-driver,http-driver,bolt-driver

<!-- add this dependency if you want to use the embedded driver -->

<dependency>

<groupId>org.neo4j</groupId>

<artifactId>neo4j-ogm-embedded-driver</artifactId>

<version>{ogm-version}</version>

</dependency>

<!-- add this dependency if you want to use the HTTP driver -->

<dependency>

<groupId>org.neo4j</groupId>

<artifactId>neo4j-ogm-http-driver</artifactId>

<version>{ogm-version}</version>

</dependency>

<!-- the neo4j-ogm-test jar provides access to the http and embedded drivers for testing purposes -->

<dependency> <groupId>org.neo4j</groupId> <artifactId>neo4j-ogm-test</artifactId> <version>${neo4j-ogm.version}</version> <type>test-jar</type> <scope>test</scope> </dependency>

<dependency> <groupId>org.neo4j</groupId> <artifactId>neo4j-kernel</artifactId> <version>${neo4j.version}</version> <type>test-jar</type> </dependency>

<dependency> <groupId>org.neo4j.app</groupId> <artifactId>neo4j-server</artifactId> <version>${neo4j.version}</version> <type>test-jar</type> </dependency>

<dependency> <groupId>org.neo4j.test</groupId> <artifactId>neo4j-harness</artifactId> <version>${neo4j.version}</version> <scope>test</scope> </dependency>

driver的配置,SDN会自动扫描ogn.properties文件,也可以通过java Configuration来配置,其中<driver>对应依赖中申明的driver,<uri>对应对应neo4j数据库链接地址(http://username:password@localhost:7474)如下:

import org.neo4j.ogm.config.Configuration;

@Bean

public Configuration configuration() {

Configuration config = new Configuration();

config .driverConfiguration() .setDriverClassName("org.neo4j.ogm.drivers.<driver>.driver.<driver>Driver") .setURI("<uri>");

return config;

@Bean

public SessionFactory sessionFactory() {

return new SessionFactory(configuration(), <packages> );

Neo4j OGM支持

OGM将图数据库中的节点和关系与域模型中的对象和引用映射起来,节点与对象实例映射起来,而对象引用与关系映射起来。OGM抽象化了数据库,提供一种方便的方式在图数据库持久化域模型(domain model),并且查询不需要使用低级别的驱动。

Session用于驱动对象图映射框架。所有存储库实现都是由Session驱动的。它跟踪对实体及其关系所做的更改,这样做的好处是,只需要保存修改的部分。

Neo4j Repositories使用

@Repository

public interface PersonRepository extends Neo4jRepository<Person, Long> {}

public class MySpringBean {

@Autowired private PersonRepository repo;

} // then you can use the repository as you would any other object

Person michael = repo.save(new Person("Michael", 36));

Person dave = repo.load(123);

long numberOfPeople = repo.count();

Mapping Query Results

public interface MovieRepository extends GraphRepository<Movie> {

@Query("MATCH (movie:Movie)-[r:RATING]\->(), (movie)<-[:ACTS_IN]-(actor:Actor) " + "WHERE movie.id={0} " + "RETURN movie as movie, COLLECT(actor) AS 'cast', AVG(r.stars) AS 'averageRating'")

MovieData getMovieData(String movieId);

@QueryResult

public class MovieData {

Movie movie;

Double averageRating;

Set<Actor> cast;

Neo4j是一种事务型数据库。对所有与SDN交互的方法标定@Transactional

@Service

class UserManagementImpl implements UserManagement {

private final UserRepository userRepository;

private final RoleRepository roleRepository;

@Autowired

public UserManagementImpl(UserRepository userRepository, RoleRepository roleRepository) {

this.userRepository = userRepository;

this.roleRepository = roleRepository;

@Transactional

public void addRoleToAllUsers(String roleName) {

Role role = roleRepository.findByName(roleName);

for (User user : userRepository.findAll()) {

user.addRole(role);

userRepository.save(user);

Driver Configuration