HugeGraph客户端APP开发（一）

一、简介

本文测试项目努力实现从HugeGraph-Client向HugeGraph-Server发出HTTP请求，获取并解析Server的执行结果。

注意：目前官方仅提供了Java版嵌入式开发支持，即我们可以使用HugeGraph-Client编写Java代码操作HugeGraph，实现图元数据和图数据的增删改查操作，或者执行gremlin语句。

二、测试环境

• MAC HIGH SIERRA 10.13.6
• jdk1.8
• Intelli IDEA 2021.2及内置Maven－3.6.3

根据官方资料，使用HugeGraph-Client的基本开发步骤如下:

• 新建IDEA Maven项目；
• 在pom文件中添加HugeGraph-Client依赖；
• 创建类，调用HugeGraph-Client接口；

本文正是使用上述思路创建的示例。

三、示例项目

第一步：启动IDEA创建一个空的常规Maven项目，命名为Hello1HugeGraph。

第二步：添加POM依赖项：

<?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>org.hugegraph</groupId>
    <artifactId>Hello1HugeGraph</artifactId>
    <version>1.0-SNAPSHOT</version>
    <dependencies>
        <dependency>
            <groupId>com.baidu.hugegraph</groupId>
            <artifactId>hugegraph-client</artifactId>
            <version>2.0.1</version>
        </dependency>
    </dependencies>

    <properties>
        <maven.compiler.source>11</maven.compiler.source>
        <maven.compiler.target>11</maven.compiler.target>
    </properties>

</project>

提示：在线Maven仓库（​​https://search.maven.org​​）搜索时，最好搜索artifactId项，这样定位更准确。

第三步：编写客户端APP代码。

import java.io.IOException;
import java.util.Iterator;
import java.util.List;

import com.baidu.hugegraph.driver.GraphManager;
import com.baidu.hugegraph.driver.GremlinManager;
import com.baidu.hugegraph.driver.HugeClient;
import com.baidu.hugegraph.driver.SchemaManager;

import com.baidu.hugegraph.structure.constant.T;
import com.baidu.hugegraph.structure.graph.Edge;
import com.baidu.hugegraph.structure.graph.Path;
import com.baidu.hugegraph.structure.graph.Vertex;
import com.baidu.hugegraph.structure.gremlin.Result;
import com.baidu.hugegraph.structure.gremlin.ResultSet;

public class MainAPP {

    public static void main(String[] args) throws IOException {
        // If connect failed will throw a exception.
        HugeClient hugeClient = HugeClient.builder("http://localhost:8080",
                        "hugegraph")
                .build();

        SchemaManager schema = hugeClient.schema();

        schema.propertyKey("name").asText().ifNotExist().create();
        schema.propertyKey("age").asInt().ifNotExist().create();
        schema.propertyKey("city").asText().ifNotExist().create();
        schema.propertyKey("weight").asDouble().ifNotExist().create();
        schema.propertyKey("lang").asText().ifNotExist().create();
        schema.propertyKey("date").asDate().ifNotExist().create();
        schema.propertyKey("price").asInt().ifNotExist().create();

        schema.vertexLabel("人物")
                .properties("name", "age", "city")
                .primaryKeys("name")
                .ifNotExist()
                .create();

        schema.vertexLabel("软件")
                .properties("name", "lang", "price")
                .primaryKeys("name")
                .ifNotExist()
                .create();

        schema.indexLabel("personByCity")
                .onV("人物")
                .by("city")
                .secondary()
                .ifNotExist()
                .create();

        schema.indexLabel("personByAgeAndCity")
                .onV("人物")
                .by("age", "city")
                .secondary()
                .ifNotExist()
                .create();

        schema.indexLabel("softwareByPrice")
                .onV("软件")
                .by("price")
                .range()
                .ifNotExist()
                .create();

        schema.edgeLabel("认识")
                .sourceLabel("人物")
                .targetLabel("人物")
                .properties("date", "weight")
                .ifNotExist()
                .create();

        schema.edgeLabel("开发")
                .sourceLabel("人物").targetLabel("软件")
                .properties("date", "weight")
                .ifNotExist()
                .create();

        schema.indexLabel("createdByDate")
                .onE("开发")
                .by("date")
                .secondary()
                .ifNotExist()
                .create();

        schema.indexLabel("createdByWeight")
                .onE("开发")
                .by("weight")
                .range()
                .ifNotExist()
                .create();

        schema.indexLabel("knowsByWeight")
                .onE("认识")
                .by("weight")
                .range()
                .ifNotExist()
                .create();

        GraphManager graph = hugeClient.graph();
        Vertex zhangsan = graph.addVertex(T.label, "人物", "name", "张三",
                "age", 29, "city", "Beijing");
        Vertex lisi = graph.addVertex(T.label, "人物", "name", "李四",
                "age", 27, "city", "Hongkong");
        Vertex lop = graph.addVertex(T.label, "软件", "name", "大话西游III",
                "lang", "java", "price", 328);
        Vertex wangwu = graph.addVertex(T.label, "人物", "name", "王五",
                "age", 32, "city", "Beijing");
        Vertex ripple = graph.addVertex(T.label, "软件", "name", "变脸秀APP",
                "lang", "java", "price", 199);
        Vertex maliu = graph.addVertex(T.label, "人物", "name", "麻六",
                "age", 35, "city", "Shanghai");

        zhangsan.addEdge("认识", lisi, "date", "2016-01-10", "weight", 0.5);
        zhangsan.addEdge("认识", wangwu, "date", "2013-02-20", "weight", 1.0);
        zhangsan.addEdge("开发", lop, "date", "2017-12-10", "weight", 0.4);
        wangwu.addEdge("开发", lop, "date", "2009-11-11", "weight", 0.4);
        wangwu.addEdge("开发", ripple, "date", "2017-12-10", "weight", 1.0);
        maliu.addEdge("开发", lop, "date", "2017-03-24", "weight", 0.2);

        GremlinManager gremlin = hugeClient.gremlin();

        System.out.println("==== Path ====");
        ResultSet resultSet = gremlin.gremlin("g.V().outE().path()").execute();

        Iterator<Result> results = resultSet.iterator();
        results.forEachRemaining(result -> {
            System.out.println(result.getObject().getClass());
            Object object = result.getObject();
            if (object instanceof Vertex) {
                System.out.println(((Vertex) object).id());
            } else if (object instanceof Edge) {
                System.out.println(((Edge) object).id());
            } else if (object instanceof Path) {
                List<Object> elements = ((Path) object).objects();
                elements.forEach(element -> {
                    System.out.println(element.getClass());
                    System.out.println(element);
                });
            } else {
                System.out.println(object);
            }
        });

        hugeClient.close();
    }
}

后面再专门写文分析上述代码中Gremlin脚本知识，在此省略。

四、构建并启动客户端APP

构建并运行上述程序前，需要先启动HugeGraph服务器：

$HG/bin/start-hugegraph.sh

正常启动服务器后的输出内容如下：

Starting HugeGraphServer...

Connecting to HugeGraphServer (http://127.0.0.1:8080/graphs)..............OK

Started [pid 7240]

然后，构建并运行应用程序即可。

五：观察运行结果

命令行输出如下：

六、主要参考

• ​​https://hugegraph.apache.org/cn/docs/quickstart/hugegraph-client/​​
• ​​https://tinkerpop.apache.org/docs/current/reference/​​
• ​​https://github.com/apache/incubator-hugegraph/blob/master/hugegraph-example/src/main/java/com/baidu/hugegraph/example/Example1.java​​