Neo4j在java中的使用

1.Neo4j访问的两种方式

• 嵌入式数据库
• 服务器模式(通过REST的访问)

它是由应用程序的性质（neo4j是独立服务器 还是和程序在一起),性能，监控和数据安全性来决定架构选择。

An embedded database（嵌入式数据库）

嵌入式Neo4j数据库是性能的最佳选择。 通过指定数据存储的路径以编程方式访问嵌入式数据库。

我们选择嵌入式数据库出于以下原因：

• 使用Java作为我们项目的编程语言时
• 应用程序是独立的
• 程序追求很高的性能

Neo4j Server（服务器模式）

Neo4j Server是相互操作性，安全性和监控的最佳选择。 实际上，REST接口允许所有现代平台和编程语言与它进行互操作。 此外，作为独立应用程序，它比嵌入式配置更安全（客户端中的潜在故障不会影响服务器），并且更易于监控。 如果我们选择使用这种模式，我们的应用程序将充当Neo4j服务器的客户端。要连接到Neo4j服务器，可以使用任何编程语言的REST 访问数据库。文章来源地址https://www.toymoban.com/news/detail-845533.html

2.Java客户端操作Neo4j

1…嵌入式模式

<dependency>
	<groupId>org.neo4j</groupId>
	<artifactId>neo4j</artifactId>
	<version>4.0.1</version>
</dependency>

public class EmbeddedNeo4jAdd {
    private static final File databaseDirectory = new File( "target/graph.db" );
    public static void main(String[] args) {
        GraphDatabaseService graphDb = new GraphDatabaseFactory().newEmbeddedDatabase(databaseDirectory);
        System.out.println("Database Load!");
        Transaction tx = graphDb.beginTx();
        Node n1 = graphDb.createNode();
        n1.setProperty("name", "张三");
        n1.setProperty("character", "A");
        n1.setProperty("gender",1);
        n1.setProperty("money", 1101);
        n1.addLabel(new Label() {
            @Override
            public String name() {
                return "Person";
            }
        });
        String cql = "CREATE (p:Person{name:'李四',character:'B',gender:1,money:21000})";
        graphDb.execute(cql);
        tx.success();
        tx.close();
        System.out.println("Database Shutdown!");
        graphDb.shutdown();
    }
}

public class EmbeddedNeo4jQueryAll {
    private static final File databaseDirectory = new File( "target/graph.db" );
    public static void main(String[] args) {
        GraphDatabaseService graphDb = new GraphDatabaseFactory().newEmbeddedDatabase(databaseDirectory);
        System.out.println("Database Load!");
        String cql = "MATCH (a:Person) where a.money < $money return a";
        Map<String, Object> paramerters = new HashMap<String, Object>();
        paramerters.put("money", 25000);
        Transaction tx = graphDb.beginTx();
        Result result = graphDb.execute(cql,paramerters);
        while (result.hasNext()) {
            Map<String, Object> row = result.next();
            for (String key : result.columns()) {
                Node nd = (Node) row.get(key);
                System.out.printf("%s = %s:%s%n", key,
                        nd.getProperty("name"),nd.getProperty("money"));
            }
        }
        tx.success();
        tx.close();
        System.out.println("Database Shutdown!");
        graphDb.shutdown();
    }
}

2.服务器模式

<dependency>
	<groupId>org.neo4j</groupId>
	<artifactId>neo4j-ogm-bolt-driver</artifactId>
	<version>3.2.12</version>
</dependency>

public class Neo4jServerMain {
    public static void main(String[] args) {
        Driver driver = GraphDatabase.driver( "bolt://127.0.0.1:7687", AuthTokens.basic( "neo4j", "123456" ) );
        Session session = driver.session();
        String cql = "MATCH (a:Person) WHERE a.money > $money " +
                "RETURN a.name AS name, a.money AS money order by a.money ";
        Result result = session.run( cql,parameters( "money", 1000 ) );
        while ( result.hasNext() )
        {
            Record record = result.next();
            System.out.println( record.get( "name" ).asString() + " " +
                    record.get( "money" ).asDouble() );
        }
        session.close();
        driver.close();
    }
}

public class Neo4jServerMain2 {
    public static void main(String[] args) {
        Driver driver = GraphDatabase.driver( "bolt://127.0.0.1:7687", AuthTokens.basic( "neo4j", "123456" ) );
        Session session = driver.session();
        String cql = "MATCH p=shortestPath((person:Person {name:$startName})-[*]-(person2:Person {name:$endName} )) RETURN p";
        Result result = session.run( cql,parameters("startName","王启年","endName","九品射手燕小乙") );
        while ( result.hasNext() )
        {
            Record record = result.next();
            System.out.println(record);
        }
        session.close();
        driver.close();
    }
}

3.SpringBoot 整合Neo4j

<?xml version="1.0" encoding="UTF-8"?>
<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>com.release</groupId>
    <artifactId>neo4j-demo</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>11</maven.compiler.source>
        <maven.compiler.target>11</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.1.RELEASE</version>
    </parent>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-neo4j</artifactId>
        </dependency>
        <dependency>
            <groupId>org.neo4j</groupId>
            <artifactId>neo4j-ogm-bolt-driver</artifactId>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.4</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>

</project>

@NodeEntity
@Data
public class Person {
    @Id
    @GeneratedValue
    private Long id;
    @Property("cid")
    private int pid;
    @Property
    private String name;
    private String character;
    private double money;
    private int gender;
    private int age;
    private String description;
    @Relationship(type = "Friends", direction = Relationship.INCOMING)
    private Set<Person> relationPersons;
}

@Repository
public interface PersonRepository extends Neo4jRepository<Person, Long> {

    @Query("match(p:Person) where p.money>$money return p")
    List<Person> personList(@Param("money") double money);

    /**
     * 指定开始的名字 和 结束的名字 查询最短路径 限定深度为4以层包含4
     */
    @Query("match p=shortestPath((person:Person{name:$startName})-[*1..4]- (person2:Person {name:$endName})) return p")
    List<Person> shortestPath(@Param("startName") String startName, @Param("endName") String endName);
}

@Service
public class Neo4jPersonService {

    @Autowired
    private PersonRepository personRepository;

    public List<Person> personList(double money) {
        return personRepository.personList(money);
    }

    public Person save(Person person) {
        return personRepository.save(person);
    }

    public List<Person> shortestPath(String startName, String endName) {
        return personRepository.shortestPath(startName, endName);
    }
}

@SpringBootApplication
public class TestNeo4jBootApp {

    public static void main(String[] args) {
        ApplicationContext app = SpringApplication.run(TestNeo4jBootApp.class, args);

        Neo4jPersonService personService = app.getBean(Neo4jPersonService.class);
        System.out.println(personService);
        Person person = new Person();
        person.setName("庆帝");
        person.setAge(35);
        person.setCharacter("qingdi");
        person.setGender(0);
        person.setDescription("范闲的爹");
        person.setMoney(10000);
        Person save = personService.save(person);
        System.out.println("save:" + save);
        List<Person> peopleList = personService.personList(100);
        for (Person person1 : peopleList) {
            System.out.println("person1:" + person1);
        }
    }
}

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