Eclipse下maven使用嵌入式（Embedded）Neo4j创建Hello World项目

Eclipse下maven使用嵌入式（Embedded）Neo4j创建Hello World项目

新建一个maven工程，这里不赘述如何新建maven工程。

添加Neo4j jar到你的工程

有两种方式：

• 上网站官网下载jar包，根据自己的系统下载不同的压缩包，详细过程不描述，请自行搜索其他博客
• 通过maven获得jar包

pom.xml文件下添加dependency

<project xmlns="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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>nd.esp.com</groupId>
  <artifactId>MyNeo4j</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>jar</packaging>

  <name>MyNeo4j</name>
  <url>http://maven.apache.org</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>

<!-- Embedded Neo4j依赖，目前最新版本是2.3.3-->
  <dependencies>
    <dependency>
     <groupId>org.neo4j</groupId>
     <artifactId>neo4j-slf4j</artifactId>
     <version>2.3.3</version>
    </dependency>
  </dependencies>
</project>

Hello World 程序

代码可以在github上看到：https://github.com/neo4j/neo4j/blob/2.3.3/community/embedded-examples/src/main/java/org/neo4j/examples/EmbeddedNeo4j.java

/*
 * Licensed to Neo Technology under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Neo Technology 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.
 */
package org.neo4j.examples;

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

import org.neo4j.graphdb.Direction;
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;
import org.neo4j.graphdb.factory.GraphDatabaseFactory;
import org.neo4j.io.fs.FileUtils;

public class EmbeddedNeo4j
{
	// Embedded Neo4j会在本地产生一个文件夹(类似于Mysql的数据库)
    private static final String DB_PATH = "target/neo4j-hello-db";

    public String greeting;

    // START SNIPPET: vars
    GraphDatabaseService graphDb;
    Node firstNode;
    Node secondNode;
    Relationship relationship;
    // END SNIPPET: vars

    // START SNIPPET: createReltype
    private static enum RelTypes implements RelationshipType
    {
        KNOWS
    }
    // END SNIPPET: createReltype

    public static void main( final String[] args ) throws IOException
    {
        EmbeddedNeo4j hello = new EmbeddedNeo4j();
        hello.createDb();
		// 删除数据
        hello.removeData();
        hello.shutDown();
    }

    void createDb() throws IOException
    {
        FileUtils.deleteRecursively( new File( DB_PATH ) );

        // START SNIPPET: startDb
        graphDb = new GraphDatabaseFactory().newEmbeddedDatabase( DB_PATH );
        registerShutdownHook( graphDb );
        // END SNIPPET: startDb

        // START SNIPPET: transaction
		// Embedded Neo4j基本上所有的操作都需要在事务内执行
        try ( Transaction tx = graphDb.beginTx() )
        {
            // Database operations go here
            // END SNIPPET: transaction
            // START SNIPPET: addData
            firstNode = graphDb.createNode();
            firstNode.setProperty( "message", "Hello, " );
            secondNode = graphDb.createNode();
            secondNode.setProperty( "message", "World!" );

            relationship = firstNode.createRelationshipTo( secondNode, RelTypes.KNOWS );
            relationship.setProperty( "message", "brave Neo4j " );
            // END SNIPPET: addData

            // START SNIPPET: readData
            System.out.print( firstNode.getProperty( "message" ) );
            System.out.print( relationship.getProperty( "message" ) );
            System.out.print( secondNode.getProperty( "message" ) );
            // END SNIPPET: readData

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

            // START SNIPPET: transaction
            tx.success();
        }
        // END SNIPPET: transaction
    }
	// 移除新建的数据
    void removeData()
    {
        try ( Transaction tx = graphDb.beginTx() )
        {
            // START SNIPPET: removingData
            // let's remove the data
            firstNode.getSingleRelationship( RelTypes.KNOWS, Direction.OUTGOING ).delete();
            firstNode.delete();
            secondNode.delete();
            // END SNIPPET: removingData

            tx.success();
        }
    }
	// 关闭Neo4j 数据库
    void shutDown()
    {
        System.out.println();
        System.out.println( "Shutting down database ..." );
        // START SNIPPET: shutdownServer
        graphDb.shutdown();
        // END SNIPPET: shutdownServer
    }

    // 为Neo4j 实例注册一个关闭的hook，当VM被强制退出时，Neo4j 实例能够正常关闭
    private static void registerShutdownHook( final GraphDatabaseService graphDb )
    {
        // 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()
            {
                graphDb.shutdown();
            }
        } );
    }
}

在事务中操作

所有的操作都必须在一个事务中完成。这是官方一个刻意的设计，因为他们坚信事务划分是企业型数据库重要的一部分。所以，你可以使用如下的方式开启事务：

try ( Transaction tx = graphDb.beginTx() ){

// Database operations go here

tx.success();

}

try(){}这种语法是在jdk1.7之后支持的，这种方式能够让vm支持自动释放使用结束的资源。在这里可以不需要自己调用语句:

finally{

tx.close();

}

如果你使用低于jdk1.7以后的版本，可以修改为如下的代码：

Transaction tx = graphDb.beginTx()

try{

// Database operations go here

tx.success();

}finally{

tx.close();

}

创建一个简单的图

使用一下代码创建两个节点和一个关系：

firstNode = graphDb.createNode();
firstNode.setProperty( "message", "Hello, " );
secondNode = graphDb.createNode();
secondNode.setProperty( "message", "World!" );

relationship = firstNode.createRelationshipTo( secondNode, RelTypes.KNOWS );
relationship.setProperty( "message", "brave Neo4j " );

创建之后的图数据如下：

本文翻译自官网使用手册：http://neo4j.com/docs/stable/tutorials-java-embedded-hello-world.html

教程结束，感谢阅读。

欢迎转载，但请注明本文链接，谢谢。

2016/4/5 20:09:25