该文演示了一个使用Neo4J数据库和Neo4J OGM的Quarkus应用程序示例，代码：GitHub
在当前版本中1.4.2.Final，Quarkus带有基本的Neo4J支持，但是截至撰写本文时，还没有包括对OGM映射的支持。但是，我们可以使用一个简单的生产者来添加支持，该生产者公开了Neo4J OGM SessionFactory：
import org.neo4j.ogm.config.Configuration;
import org.neo4j.ogm.session.SessionFactory;
...
@ApplicationScoped
public class SessionFactoryProducer {
public static final String PACKAGE = "com.sebastian_daschner.coffee.entity";
@ConfigProperty(name = "quarkus.neo4j.uri")
String databaseUri;
@ConfigProperty(name = "quarkus.neo4j.authentication.username")
String username;
@ConfigProperty(name = "quarkus.neo4j.authentication.password")
String password;
@Produces
SessionFactory produceSessionFactory() {
Configuration neoConfig = new Configuration.Builder()
.uri(databaseUri)
.credentials(username, password)
.useNativeTypes()
.build();
return new SessionFactory(neoConfig, PACKAGE);
}
void disposeSessionFactory(@Disposes SessionFactory sessionFactory) {
sessionFactory.close();
}
}
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现在我们可以将注入到SessionFactorybean中，并使用它来查询图数据库：
import org.neo4j.ogm.session.*;
...
@ApplicationScoped
public class CoffeeBeans {
@Inject
SessionFactory sessionFactory;
public List<CoffeeBean> getCoffeeBeans() {
Session session = sessionFactory.openSession();
return new ArrayList<>(session.loadAll(CoffeeBean.class,
new SortOrder("name"), 1));
}
public List<CoffeeBean> getCoffeeBeansSpecificFlavor(String flavor) {
Session session = sessionFactory.openSession();
Iterable<CoffeeBean> result = session.query(CoffeeBean.class,
"MATCH (b:CoffeeBean)-[:TASTES]->(:Flavor {description: $flavor})\n" +
"MATCH (b)-[isFrom:IS_FROM]->(country)\n" +
"MATCH (b)-[tastes:TASTES]->(flavor)\n" +
"RETURN b, collect(isFrom), collect(country)," +
" collect(tastes), collect(flavor)\n" +
"ORDER by b.name;",
Map.of("flavor", flavor));
return resultList(result);
}
...
}
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CoffeeBean对象是通过Neo4J OGM映射的：
import org.neo4j.ogm.annotation.*;
...
@NodeEntity
public class CoffeeBean {
@Id
public String name;
@Relationship("IS_FROM")
public Set<Origin> origins = new HashSet<>();
@Property
public Roast roast;
@Relationship("TASTES")
public Set<FlavorProfile> flavorProfiles = new HashSet<>();
...
}
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