不同语言下的CypherSDK如何使用_图数据库(Graph Database)-阿里云帮助中心

Java

环境准备

安装JDK 1.8以上版本。
安装maven。

代码示例

创建并进入项目目录。

mkdir cypher-java-example
cd cypher-java-example

创建pom.xml文件，内容如下。

<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/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.gdb.alibaba</groupId>
  <artifactId>GdbGremlinExample</artifactId>
  <packaging>jar</packaging>
  <version>1.0-SNAPSHOT</version>
  <name>GdbGremlinExample</name>
  <url>http://maven.apache.org</url>
  <dependencies>
    <dependency>
       <groupId>org.neo4j.driver</groupId>
       <artifactId>neo4j-java-driver</artifactId>
       <version>4.0.1</version>
    </dependency>
  </dependencies>
  <build>
     <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>2.0.2</version>
            <configuration>
                <source>1.8</source>
                <target>1.8</target>
            </configuration>
        </plugin>
        <plugin>
            <groupId>org.codehaus.mojo</groupId>
            <artifactId>exec-maven-plugin</artifactId>
            <version>1.3</version>
            <configuration>
                <mainClass>com.example.gdb.HelloWorld</mainClass>
                <complianceLevel>1.8</complianceLevel>
            </configuration>
        </plugin>
    </plugins>
  </build>
</project>

创建源码目录。
```
mkdir -p src/main/java/com/example/gdb/
```

编辑文件src/main/java/com/example/gdb/HelloWorld.java。其中GDB_HOST、GDB_PORT、GDB_USER、GDB_PASSWORD分别替换成对应实例的地址、端口、用户名和密码。

package com.example.gdb;
import org.neo4j.driver.AuthTokens;
import org.neo4j.driver.Driver;
import org.neo4j.driver.GraphDatabase;
import org.neo4j.driver.Session;
import org.neo4j.driver.Result;
import org.neo4j.driver.Transaction;
import org.neo4j.driver.TransactionWork;
import static org.neo4j.driver.Values.parameters;
public class HelloWorld implements AutoCloseable
{
    private final Driver driver;
    public HelloWorld( String uri, String user, String password )
    {
        driver = GraphDatabase.driver( uri, AuthTokens.basic( user, password ) );
    }
    @Override
    public void close() throws Exception
    {
        driver.close();
    }
    public void printGreeting( final String message )
    {
        try ( Session session = driver.session() )
        {
            String greeting = session.writeTransaction( new TransactionWork<String>()
            {
                @Override
                public String execute( Transaction tx )
                {
                    Result result = tx.run( "CREATE (a:Greeting) " +
                                                     "SET a.message = $message " +
                                                     "RETURN a.message + ', from node ' + id(a)",
                            parameters( "message", message ) );
                    return result.single().get( 0 ).asString();
                }
            } );
            System.out.println( greeting );
        }
    }
    public static void main( String... args ) throws Exception
    {
        try ( HelloWorld greeter = new HelloWorld( "bolt://GDB_HOST:GDB_PORT", "GDB_USER", "GDB_PASSWORD" ) )
        {
            greeter.printGreeting( "hello" );
        }
    }
}

编译运行。

mvn compile exec:java

实例运行结果如下：

hello, from node 1000010

Python

环境准备

安装CPython 2.7或3.4以上，建议Python3。
安装pip。
安装neo4j driver。如果同时安装了多个版本的python和pip，需要用pip2或者pip3为指定版本安装。
```
pip install neo4j --user
```

代码示例

编辑文件cypher-python-example.py，内容如下。其中GDB_HOST、GDB_PORT、GDB_USER、GDB_PASSWORD分别替换成对应实例的地址、端口、用户名和密码。

from neo4j import GraphDatabase
class HelloWorldExample(object):
    def __init__(self, uri, user, password):
        self._driver = GraphDatabase.driver(uri,
                                            auth=(user, password),
                                            encrypted=False)
    def close(self):
        self._driver.close()
    def print_greeting(self, message):
        with self._driver.session() as session:
            greeting = session.write_transaction(
                self._create_and_return_greeting, message)
            print(greeting)
    @staticmethod
    def _create_and_return_greeting(tx, message):
        result = tx.run(
            "CREATE (a:Greeting) "
            "SET a.message = $message "
            "RETURN a.message + ', from node ' + id(a)",
            message=message)
        return result.single()[0]
e = HelloWorldExample('bolt://GDB_HOST:GDB_PORT', 'GDB_USER', 'GDB_PASSWORD')
r = e.print_greeting('hello')

编译运行。

python cypher-python-example.py

运行结果如下：

hello, from node 1000003

Neo4j Python driver的更多信息，请参阅Neo4j官网文档。

Go

环境准备

安装go 1.11以上。

安装seabolt。Neo4j go driver依赖于seabolt，推荐从源码编译安装。安装方法以Mac OS为例，其他安装方法参考seabolt的Github主页。

# 安装openssl
brew install openssl
# 设置环境变量OPENSSL_ROOT_DIR
export OPENSSL_ROOT_DIR=/usr/local/opt/openssl
# 解压seabolt源码包
tar zxvf seabolt-1.7.4.tar.gz
cd seabolt-1.7.4
mkdir build && cd build
cmake ..
make install

代码示例

创建和初始化项目目录。

mkdir cypher-go-example
cd cypher-go-example
go mod init cypher-go-example

编辑main.go文件，内容如下。其中GDB_HOST、GDB_PORT、GDB_USER、GDB_PASSWORD分别替换成对应实例的地址、端口、用户名和密码。

package main
import (
    "fmt"
    "github.com/neo4j/neo4j-go-driver/neo4j"
)
func helloWorld(uri, username, password string) (string, error) {
    var (
        err      error
        driver   neo4j.Driver
        session  neo4j.Session
        result   neo4j.Result
        greeting interface{}
    )
    driver, err = neo4j.NewDriver(uri, neo4j.BasicAuth(username, password, ""))
    if err != nil {
        return "", err
    }
    defer driver.Close()
    session, err = driver.Session(neo4j.AccessModeWrite)
    if err != nil {
        return "", err
    }
    defer session.Close()
    greeting, err = session.WriteTransaction(func(transaction neo4j.Transaction) (interface{}, error) {
        result, err = transaction.Run(
            "CREATE (a:Greeting) SET a.message = $message RETURN a.message + ', from node ' + id(a)",
            map[string]interface{}{"message": "hello"})
        if err != nil {
            return nil, err
        }
        if result.Next() {
            return result.Record().GetByIndex(0), nil
        }
        return nil, result.Err()
    })
    if err != nil {
        return "", err
    }
    return greeting.(string), nil
}
func main() {
    greeting, err := helloWorld("bolt://GDB_HOST:GDB_PORT", "GDB_USER", "GDB_PORT")
    if err != nil {
        fmt.Println(err)
    }
    fmt.Println(string(greeting))
}

编译并运行示例，go会自动下载安装driver并添加依赖关系到go.mod文件中。
```
go build ./.. && ./cypher-go-example
# 或者
go run main.go
```
示例运行结果如下：
```
hello, from node 1000004
```

.Net

环境准备：下载安装.net，版本2.0以上。

代码示例

创建项目，并进入项目目录。

dotnet new console -o cypher-dotnet-example
cd cypher-dotnet-example

安装Neo4j.Driver。
```
dotnet add package Neo4j.Driver.Simple
```

编辑Program.cs，内容如下。其中GDB_HOST、GDB_PORT、GDB_USER、GDB_PASSWORD分别替换成对应实例的地址、端口、用户名和密码。

using System;
using System.Linq;
using Neo4j.Driver;
namespace cypherTest
{
    public class HelloWorldExample : IDisposable
    {
        private readonly IDriver _driver;
        public HelloWorldExample(string uri, string user, string password)
        {
            _driver = GraphDatabase.Driver(uri, AuthTokens.Basic(user, password));
        }
        public void PrintGreeting(string message)
        {
            using (var session = _driver.Session())
            {
                var greeting = session.WriteTransaction(tx =>
                {
                    var result = tx.Run("CREATE (a:Greeting) " +
                                        "SET a.message = $message " +
                                        "RETURN a.message + ', from node ' + id(a)",
                        new {message});
                    return result.Single()[0].As<string>();
                });
                Console.WriteLine(greeting);
            }
        }
        public void Dispose()
        {
            _driver?.Dispose();
        }
        public static void Main()
        {
            using (var greeter = new HelloWorldExample("bolt://GDB_HOST:GDB_PORT", "GDB_USER", "GDB_PASSWORD"))
            {
                greeter.PrintGreeting("hello");
            }
        }
    }
}

编译运行。
```
dotnet run
```
实例运行结果如下：
```
hello, from node 1000007
```

Neo4j .Net driver的更多信息，请参阅Neo4j官方文档。

Node.js

环境准备：安装Node.js，建议使用LTS版本（10.x、12.x）。

代码示例

新建并进入项目目录。

mkdir cypher-js-example
cd cypher-js-example

添加Neo4j driver。
```
npm install neo4j-driver
```

编辑demo.js，内容如下。其中GDB_HOST、GDB_PORT、GDB_USER、GDB_PASSWORD分别替换成对应实例的地址、端口、用户名和密码。

const neo4j = require("neo4j-driver");
const driver = neo4j.driver('bolt://GDB_HOST:GDB_PORT',
                            neo4j.auth.basic('GDB_USER', 'GDB_PASSWORD'));
async function helloWorld() {
  const session = driver.session();
  try {
    const result = await session.writeTransaction(
        tx => tx.run(
            'CREATE (a:Greeting) SET a.message = $message RETURN a.message + ", from node " + id(a)',
            {message : 'hello'}));
    const singleRecord = result.records[0];
    const greeting = singleRecord.get(0);
    return greeting;
  } finally {
    await session.close();
  }
}
helloWorld().then(msg => {
  console.log(msg);
  driver.close();
});

编译运行。
```
node demo.js
```
实例运行结果如下：
```
hello, from node 1000008
```

Neo4j Javascript driver的更多信息，请参阅Neo4j官方文档。