执行GQL

本节介绍如何使用gql()和gqlStream()方法在数据库中执行GQL。

GQL（图查询语言）是ISO标准化的图数据库查询语言。详情参阅GQL文档。

gql()

在数据库中执行GQL语句。

参数

• gql: String：待执行的GQL语句。
• config: RequestConfig（可选）：请求配置。

返回值

• Response：请求结果。

// Retrieves 5 movie nodes from the graph 'miniCircle' and prints their names

RequestConfig requestConfig = new RequestConfig();
requestConfig.setGraph("miniCircle");

Response response = driver.gql("MATCH (n:movie) RETURN n LIMIT 5", requestConfig);
List<Node> nodeList = response.alias("n").asNodes();
for (Node node : nodeList) {
    System.out.println(node.get("name"));
}

The Shawshank Redemption
Farewell My Concubine
Léon: The Professional
Titanic
Life is Beautiful

gqlStream()

在数据库中执行GQL语句并以增量形式返回结果。在处理大型数据集时，避免同时加载所有数据至内存中。

参数

• gql: String：待执行的GQL语句。
• cb: QueryResponseListener：流处理监听器。
• config: RequestConfig（可选）：请求配置。

返回值

• None

// Retrieves all 1-step paths from the graph 'miniCircle'

RequestConfig requestConfig = new RequestConfig();
requestConfig.setGraph("miniCircle");

driver.gqlStream("MATCH p = ()-[]-() RETURN p", new QueryResponseListener() {
    int count = 0;

    public void onReady() {
        System.out.println("Start downloading");
    }

    public void next(Response response) {
        if (response.getStatus().getCode() != Ultipa.ErrorCode.SUCCESS){
          System.out.println(response.getStatus().getMsg());
        }
        Graph graph = response.get(0).asGraph();
        List<Path> paths = graph.getPaths();
        count += paths.size();
    	System.out.println("count = " + count);
    }

    public void onComplete() {
  	    System.out.println("Done");
    	System.out.println("count = " + count);
    }

    public void onError(Throwable throwable) {
    	System.out.println("Error");
    }
}, requestConfig);

count = 1024
count = 2048
count = 3072
count = 3220
count = 3621
count = 3849
Done
count = 3849

完整示例

package com.ultipa.www.sdk.api;

import com.ultipa.sdk.UltipaDriver;
import com.ultipa.sdk.connect.conf.RequestConfig;
import com.ultipa.sdk.connect.conf.UltipaConfig;
import com.ultipa.sdk.operate.entity.Node;
import com.ultipa.sdk.operate.response.Response;
import org.assertj.core.util.Lists;

import java.util.List;

public class Main {
    public static void main(String[] args) {
        UltipaConfig ultipaConfig = UltipaConfig.config()
                // URI example: .hosts(Lists.newArrayList("d3026ac361964633986849ec43b84877s.eu-south-1.cloud.ultipa.com:8443"))
                .hosts(Lists.newArrayList("192.168.1.85:60061","192.168.1.88:60061","192.168.1.87:60061"))
                .username("<username>")
                .password("<password>");

        UltipaDriver driver = null;

        try {
            driver = new UltipaDriver(ultipaConfig);

            // Retrieves 5 movie nodes from the graph 'miniCircle'

            RequestConfig requestConfig = new RequestConfig();
            requestConfig.setGraph("miniCircle");

            Response response = driver.gql("MATCH (n:movie) RETURN n LIMIT 5", requestConfig);
            List<Node> nodeList = response.alias("n").asNodes();
            for (Node node : nodeList) {
                System.out.println(node.get("name"));
            }
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        } finally {
            if (driver != null) {
                driver.close();
            }
        }
    }
}