默认密码
登录：http://localhost:7474/browser/
修改密码，可以设置为 neo4j/neo4j
新建一个数据库
默认的好像不行。
可以直接重新创建一个 DBMS 库，然后指定对应的密码为 12345678。
初始化密码
查看
通过 neo4j browser
[plaintext]
1
2
3
4
5
6
7$ SHOW USERS
╒═══════╤═══════════════════╤══════════════════════╤═════════╤════╕
│user │roles │passwordChangeRequired│suspended│home│
╞═══════╪═══════════════════╪══════════════════════╪═════════╪════╡
│"neo4j"│["admin", "PUBLIC"]│false │false │null│
└───────┴───────────────────┴──────────────────────┴─────────┴────┘
初始化测试数据
插入一个 Person 类别的节点，且这个节点有一个属性 name，属性值为 Node A。另一个节点 Node B。
[plaintext]
1
2CREATE (a:Person { name : 'Node A'});
CREATE (b:Person { name : 'Node B'});
执行查询
[plaintext]
1$ MATCH (n) return n;
结果：
[plaintext]
1
2
3
4
5
6
7╒══════════════════════════╕
│n │
╞══════════════════════════╡
│(:Person {name: "Node A"})│
├──────────────────────────┤
│(:Person {name: "Node B"})│
└──────────────────────────┘
Java Integration
maven 引入
[xml]
1
2
3
4
5<dependency>
<groupId>org.neo4j.driver</groupId>
<artifactId>neo4j-java-driver</artifactId>
<version>4.0.0</version> <!-- 替换为最新版本号 -->
</dependency>
测试代码
[java]
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31package org.example;
import org.neo4j.driver.*;
public class Main {
public static void main(String[] args) {
String uri = "bolt://localhost:7687"; // Neo4j数据库的URI
String username = "neo4j";
String password = "12345678";
try (Driver driver = GraphDatabase.driver(uri, AuthTokens.basic(username, password));
Session session = driver.session()) {
// 执行Cypher查询
String cypherQuery = "MATCH (n) RETURN n LIMIT 10";
Result result = session.run(cypherQuery);
// 处理查询结果
while (result.hasNext()) {
Record record = result.next();
// 处理每个记录...
System.out.println(record);
}
} catch (Exception e) {
// 处理异常...
e.printStackTrace();
}
}
}
日志
[plaintext]
1
2
3
4
5
6
7
8十月 21, 2023 3:28:28 下午 org.neo4j.driver.internal.logging.JULogger info
信息: Direct driver instance 167185492 created for server address localhost:7687
Record<{n: node<0>}>
Record<{n: node<1>}>
十月 21, 2023 3:28:29 下午 org.neo4j.driver.internal.logging.JULogger info
信息: Closing driver instance 167185492
十月 21, 2023 3:28:29 下午 org.neo4j.driver.internal.logging.JULogger info
信息: Closing connection pool towards localhost:7687
Record 两行已经输出。
CRUD
说明
上面只是一个启动的例子，我们还是给出一个完整的 CRUD 的入门例子
实体
我们创建一个实体。
[java]
1
2
3
4
5
6
7
8public class PersonBean {
private String id;
private String name;
// get&set
}
针对 id 添加唯一索引
[sql]
1CREATE CONSTRAINT ON (p:Person) ASSERT p.id IS UNIQUE;
insert
[java]
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37package com.github.houbb.neo4j.learn;
import com.github.houbb.neo4j.learn.model.PersonBean;
import org.neo4j.driver.*;
public class InsertDemo {
public static void main(String[] args) {
// Neo4j数据库连接信息
String uri = "bolt://localhost:7687"; // Neo4j数据库地址
String user = "neo4j"; // 数据库用户名
String password = "12345678"; // 数据库密码
// 创建驱动程序
Driver driver = GraphDatabase.driver(uri, AuthTokens.basic(user, password));
// 创建一个Person对象
PersonBean person = new PersonBean();
person.setName("John Doe");
person.setId("1");
// 执行插入操作
try (Session session = driver.session()) {
session.writeTransaction(transaction -> {
transaction.run("CREATE (p:Person {id: $id, name: $name})",
Values.parameters("id", person.getId(), "name", person.getName()));
return null;
});
} catch (Exception e) {
e.printStackTrace();
} finally {
// 关闭驱动程序
driver.close();
}
}
}
我们可以通过上面的方式插入。
但是插入 2 次会有报错：
[plaintext]
1
2
3
4
5
6
7
8
9
10
11org.neo4j.driver.exceptions.ClientException: Node(15) already exists with label `Person` and property `id` = '1'
at org.neo4j.driver.internal.util.Futures.blockingGet(Futures.java:143)
at org.neo4j.driver.internal.InternalTransaction.commit(InternalTransaction.java:39)
at org.neo4j.driver.internal.InternalSession.lambda$transaction$4(InternalSession.java:154)
at org.neo4j.driver.internal.retry.ExponentialBackoffRetryLogic.retry(ExponentialBackoffRetryLogic.java:101)
at org.neo4j.driver.internal.InternalSession.transaction(InternalSession.java:146)
at org.neo4j.driver.internal.InternalSession.writeTransaction(InternalSession.java:124)
at org.neo4j.driver.internal.InternalSession.writeTransaction(InternalSession.java:118)
at com.github.houbb.neo4j.learn.InsertDemo.main(InsertDemo.java:24)
Suppressed: org.neo4j.driver.exceptions.ClientException: Transaction can't be committed. It has been rolled back either because of an error or explicit termination
at org.neo4j.driver.internal.async.UnmanagedTransaction.doCommitAsync(UnmanagedTransaction.java:195)
merge
有没有什么方法可以让不存在时插入，存在时更新呢？
[java]
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25package com.github.houbb.neo4j.learn;
import com.github.houbb.neo4j.learn.model.PersonBean;
import org.neo4j.driver.*;
public class MergeDemo {
public static void main(String[] args) {
// Neo4j数据库连接信息
String uri = "bolt://localhost:7687"; // Neo4j数据库地址
String user = "neo4j"; // 数据库用户名
String password = "12345678"; // 数据库密码
// 执行插入操作
try (Driver driver = GraphDatabase.driver(uri, AuthTokens.basic(user, password));
Session session = driver.session()) {
String cypherQuery = "MERGE (p:Person {id: $id}) SET p.name = $name";
session.run(cypherQuery, Values.parameters("id", "2", "name", "John Doe New"));
} catch (Exception e) {
e.printStackTrace();
}
// 关闭驱动程序
}
}
update
[java]
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22package com.github.houbb.neo4j.learn;
import org.neo4j.driver.*;
public class UpdateDemo {
public static void main(String[] args) {
// Neo4j数据库连接信息
String uri = "bolt://localhost:7687"; // Neo4j数据库地址
String user = "neo4j"; // 数据库用户名
String password = "12345678"; // 数据库密码
try (Driver driver = GraphDatabase.driver(uri, AuthTokens.basic(user, password));
Session session = driver.session()) {
String cypherQuery = "MATCH (p:Person {id: $id}) SET p.name = $newName";
session.run(cypherQuery, Values.parameters("id", "1", "newName", "Updated Name"));
} catch (Exception e) {
e.printStackTrace();
}
}
}
把 id=1 的名称改掉。
query
根据 id 查询对应的 neo4j 信息。
[java]
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36package com.github.houbb.neo4j.learn;
import org.neo4j.driver.*;
import org.neo4j.driver.types.Node;
public class QueryDemo {
public static void main(String[] args) {
// Neo4j数据库连接信息
String uri = "bolt://localhost:7687"; // Neo4j数据库地址
String user = "neo4j"; // 数据库用户名
String password = "12345678"; // 数据库密码
try (Driver driver = GraphDatabase.driver(uri, AuthTokens.basic(user, password));
Session session = driver.session()) {
// 执行Cypher查询
String cypherQuery = "MATCH (p:Person) RETURN p LIMIT 10";
Result result = session.run(cypherQuery);
while (result.hasNext()) {
// 首先获取节点
Record record = result.next();
Node personNode = record.get("p").asNode();
// 从节点中获取属性
String name = personNode.get("name").asString();
String id = personNode.get("id").asString();
System.out.println(id + "=" + name);
}
} catch (Exception e) {
e.printStackTrace();
}
// 关闭驱动程序
}
}
remove
[java]
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23package com.github.houbb.neo4j.learn;
import org.neo4j.driver.*;
public class RemoveDemo {
public static void main(String[] args) {
// Neo4j数据库连接信息
String uri = "bolt://localhost:7687"; // Neo4j数据库地址
String user = "neo4j"; // 数据库用户名
String password = "12345678"; // 数据库密码
// 执行插入操作
try (Driver driver = GraphDatabase.driver(uri, AuthTokens.basic(user, password));
Session session = driver.session()) {
String cypherQuery = "MATCH (p:Person {id: $id}) DELETE p";
session.run(cypherQuery, Values.parameters("id", "1"));
} catch (Exception e) {
e.printStackTrace();
}
}
}
小结
这只是一个简单的 java 直连代码，相信 spring 整合等常见的整合一定可以。
后续有时间继续整理。
下一节我们先来看一下以 ORM 思想的操作。
参考资料
https://www.cnblogs.com/liaozk/p/17138133.html
https://blog.csdn.net/weixin_44673217/article/details/125149017
https://blog.51cto.com/u_16213367/7336746
