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

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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> <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：