Neo4j社区4.1.1中的Java嵌入式图

问题描述

我试图在Neo4j社区中可视化Java嵌入式图。

我的代码可以生成我想可视化的new.db：

/*
 * Licensed to Neo4j under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional @R_543_4045@ion regarding copyright
 * ownership. Neo4j licenses this file to you under
 * the Apache License,Version 2.0 (the "License"); you may
 * not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,* software distributed under the License is distributed on an
 * "AS IS" BASIS,WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND,either express or implied. See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

import java.io.File;
import java.io.IOException;

import org.neo4j.dbms.api.DatabaseManagementService;
import org.neo4j.dbms.api.DatabaseManagementServiceBuilder;
import org.neo4j.graphdb.GraphDatabaseService;
import org.neo4j.graphdb.Node;
import org.neo4j.graphdb.Relationship;
import org.neo4j.graphdb.RelationshipType;
import org.neo4j.graphdb.Transaction;

public class Embedded3 {
    private static final File databaseDirectory = new File(
            "/home/nicolas/neo4j-community-4.1.1/data/databases/new.db");

    public String greeting;

    // tag::vars[]
    GraphDatabaseService graphDb;
    Node firstNode;
    Node secondNode;
    Relationship relationship;
    private DatabaseManagementService managementService;
    // end::vars[]

    // tag::createReltype[]
    private enum RelTypes implements RelationshipType {
        KNowS
    }
    // end::createReltype[]

    public static void main(final String[] args) throws IOException {
        Embedded3 hello = new Embedded3();
        hello.createDb();
        // hello.removeData();
        hello.shutDown();
    }

    void createDb() throws IOException {
        // tag::startDb[]
        managementService = new DatabaseManagementServiceBuilder(databaseDirectory).build();
        graphDb = managementService.database("neo4j");
        registerShutdownHook(managementService);
        
        try (Transaction tx = graphDb.beginTx()) {

            // Database operations go here
            firstNode = tx.createNode();
            firstNode.setProperty("message","Hello,");
            secondNode = tx.createNode();
            secondNode.setProperty("message","World!");

            relationship = firstNode.createRelationshipTo(secondNode,RelTypes.KNowS);
            relationship.setProperty("message","brave Neo4j ");
            // end::addData[]

            greeting = ((String) firstNode.getProperty("message")) + ((String) relationship.getProperty("message"))
                    + ((String) secondNode.getProperty("message"));

            // tag::transaction[]
            tx.commit();
        }
        
    }

    void shutDown() {
        System.out.println();
        System.out.println("Shutting down database ...");
        // tag::shutdownServer[]
        managementService.shutdown();
        // end::shutdownServer[]
    }

    // tag::shutdownHook[]
    private 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();
            }
        });
    }
    // end::shutdownHook[]
}

之后，我在neo4j.conf中将dbms.default_database的值更改为dbms.default_database=new.db。

启动neo4j时，数据库实现良好： Database parameters in Neo4j community

但是当我运行简单的查询MATCH (n) return n时，数据库中没有要显示的记录。

然后，我从neo4j浏览器成功创建了一些节点。但是用我的Java代码无法读取它们，数据库看起来空了。

我的代码中肯定有一个错误，但是我现在真的被卡住了。 感谢您的帮助。

尼古拉斯。

解决方法

暂无找到可以解决该程序问题的有效方法，小编努力寻找整理中！

如果你已经找到好的解决方法，欢迎将解决方案带上本链接一起发送给小编。

小编邮箱:dio#foxmail.com (将#修改为@）