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Nebula Java

Nebula Java is a Java client for connecting to and managing the Nebula Graph database.

Prerequisites

You have installed Java 8.0 or later versions.

Compatibility with Nebula Graph

Nebula Graph version Nebula Java version
2.6.1 2.6.1
2.0.1 2.0.0
2.0.0 2.0.0
2.0.0-rc1 2.0.0-rc1

Download Nebula Java

  • (Recommended) To install a specific version of Nebula Java, use the Git option --branch to specify the branch. For example, to install v2.6.1, run the following command:

    $ git clone --branch v2.6.1 https://github.com/vesoft-inc/nebula-java.git

  • To install the daily development version, run the following command to download the source code from the master branch:

    $ git clone https://github.com/vesoft-inc/nebula-java.git

Use Nebula Java

Note

We recommend that each thread uses one session. If multiple threads use the same session, the performance will be reduced.

When importing a Maven project with tools such as IDEA, set the following dependency in pom.xml.

Note

2.0.0-SNAPSHOT indicates the daily development version that may have unknown issues. We recommend that you replace 2.0.0-SNAPSHOT with a released version number to use a table version.

<dependency>
  <groupId>com.vesoft</groupId>
  <artifactId>client</artifactId>
  <version>2.0.0-SNAPSHOT</version>
</dependency>

If you cannot download the dependency for the daily development version, set the following content in pom.xml. Released versions have no such issue.

<repositories> 
  <repository> 
    <id>snapshots</id> 
    <url>https://oss.sonatype.org/content/repositories/snapshots/</url> 
  </repository> 
</repositories>

If there is no Maven to manage the project, manually download the JAR file to install Nebula Java.

Core of the example code

This sub-section shows the core of the example code. For all the code, see GraphClientExample.

NebulaPool pool = new NebulaPool();
Session session = null;
try {
    NebulaPoolConfig nebulaPoolConfig = new NebulaPoolConfig();
    nebulaPoolConfig.setMaxConnSize(100);
    List<HostAddress> addresses = Arrays.asList(new HostAddress("192.168.xx.1", 9669),
            new HostAddress("192.168.xx.2", 9670));
    pool.init(addresses, nebulaPoolConfig);
    session = pool.getSession("root", "nebula", false);

    //create space
    String space = "test";
    String createSpace = "CREATE SPACE IF NOT EXISTS " + space + " (partition_num=15, replica_factor=1, vid_type=fixed_string(30)); ";
    ResultSet resp = session.execute(createSpace);


    //create schema
    String createSchema = "USE " + space + "; CREATE TAG IF NOT EXISTS person(name string, age int);"
            + "CREATE EDGE IF NOT EXISTS like(likeness double)";
    ResultSet resp = session.execute(createSchema);

    //insert vertex
    String insertVertexes = "INSERT VERTEX person(name, age) VALUES " + "'Bob':('Bob', 10), "
            + "'Lily':('Lily', 9), " + "'Tom':('Tom', 10), " + "'Jerry':('Jerry', 13), "
            + "'John':('John', 11);";
    ResultSet resp = session.execute(insertVertexes);

    // inert edge
    String insertEdges = "INSERT EDGE like(likeness) VALUES " + "'Bob'->'Lily':(80.0), "
            + "'Bob'->'Tom':(70.0), " + "'Lily'->'Jerry':(84.0), " + "'Tom'->'Jerry':(68.3), "
            + "'Bob'->'John':(97.2);";
    ResultSet resp = session.execute(insertEdges);

    // query
    String query = "GO FROM \"Bob\" OVER like " + "YIELD properties($$).name, properties($$).age, properties(edge).likeness";
    ResultSet resp = session.execute(query);
    printResult(resp);
}finally {
  if (session != null) {
      session.release();
  }
  pool.close();
}
Last update: October 22, 2021
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