Neo4j的Java API操作

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0. 写在前面

• Linux版本：Ubuntu Kylin 16.04
• Neo4j版本：Neo4j-3.2.7 Community
• Project Build Tool：Maven

1、前置芝士

Neo4j的核心概念

• Label：标签
• Node：节点，节点可以包含多个标签
• Relationship：节点与节点之间的关系。关系有始有终，有进有出，从from到to定义节点的关系
• Properties：属性。每个节点都拥有一个或多个属性

常见的增删改查操作

• 创建新节点
• 增加节点间的关系
• 修改指定属性的值
• 删除节点
• 删除节点间的指定关系

2. 准备工作

2.1 为项目引入Neo4j依赖

Maven：引入适合自己的artifactId版本。

<project>
...
 <dependencies>
  <dependency>
   <groupId>org.neo4j</groupId>
   <artifactId>neo4j</artifactId>
   <version>3.2.7</version>
  </dependency>
  ...
 </dependencies>
...
</project>

Eclipse and Maven：

对于此种模式，建议安装m2e插件，让Maven来管理项目的构建classpath。这也为通过Maven的命令行
构建项目提供了可能，同时也为开发提供了一个有效的Eclipse setup 。

2.2 启动和停止

Start

为了启动嵌入式DBMS，需要实例化一个DatabaseManagementService，并获得GraphDatabaseService，如下所示：

managementService = new DatabaseManagementServiceBuilder(databaseDirectory).build();
graphDb = managementService.database(DEFAULT_DATABASE_NAME);
registerShutdownHook(managementService);

如果你打算操作嵌入式集群，那么你应该使用com.neo4j.dbms.api.ClusterDatabaseManagementServiceBuilder来进行适当的配置。出于可维护性的考虑，你可以在neo4j.conf文件中定义你的嵌入式DBMS配置，如下所示。

dbms.mode=CORE
dbms.default_advertised_address=core01.example.com
dbms.default_listen_address=0.0.0.0
causal_clustering.discovery_type=LIST
causal_clustering.initial_discovery_members=core01.example.com,core02.example.com,core03.example.com
dbms.connector.bolt.enabled=true
dbms.connector.http.enabled=true

var managementService = new ClusterDatabaseManagementServiceBuilder( homeDirectory )
    .loadPropertiesFromFile( "/path/to/neo4j.conf" )
    .build();

Stop

为了确保Neo4j能够正常关闭Neo4j，需要申请一个hook，调用shutdown()方法。

public static void registerShutdownHook(final DatabaseManagementService managementService) {
    // Registers a shutdown hook for the Neo4j instance so that it
    // shuts down nicely when the VM exits (even if you "Ctrl-C" the
    // running application).
    Runtime.getRuntime().addShutdownHook(new Thread() {
        @Override
        public void run() {
            managementService.shutdown();
        }
    });
}

3、Java操作Neo4j

代码

import org.neo4j.driver.v1.*;
import static org.neo4j.driver.v1.Values.parameters;
public class Demo {
    public static void main( String[] args ) {
        Driver driver = GraphDatabase.driver( "bolt://localhost:7687", AuthTokens.basic( "neo4j", "neo4j_123456" ) );
        Session session = driver.session();
        session.run( "CREATE (a:Person {name: {name}, title: {title}})",
                parameters( "name", "Arthur001", "title", "King001" ) );

        StatementResult result = session.run( "MATCH (a:Person) WHERE a.name = {name} " +
                        "RETURN a.name AS name, a.title AS title",
                parameters( "name", "Arthur001" ) );
        while ( result.hasNext() )
        {
            Record record = result.next();
            System.out.println( record.get( "title" ).asString() + " " + record.get( "name" ).asString() );
        }
        session.close();
        driver.close();
    }
}

4、参考资料

neo4j

结束！