Skip to content

Java SDK guide

This guide introduces how to set up the Java SDK to connect to NebulaGraph and perform simple queries.

Prerequisites

  • JDK 8 is installed.
  • Connection information is obtained from NebulaGraph Cloud. For more information, see Connect to your database.

Steps

  1. Import the Java SDK into your Java project. For example, to import with Maven, add the following dependency to the pom.xml file:

    <dependency>
  <groupId>com.vesoft</groupId>
  <artifactId>driver</artifactId>
  <version>5.0.0</version>
</dependency>

    Note: After you reference the NebulaGraph SDK dependency in a project and package it as a JAR file, if you encounter the exception java.lang.IllegalArgumentException: Address types of NameResolver 'unix' for '192.168.15.8:9669' not supported by transport when running this JAR file, add the plugin maven-shade-plugin to your project's pom.xml file and configure the transformer as follows:

      <plugin>
              <groupId>org.apache.maven.plugins</groupId>
              <artifactId>maven-shade-plugin</artifactId>
              <version>3.4.1</version>
              <configuration>
                  <!-- put your configurations here -->
                  <filters>
                      <filter>
                          <artifact>*:*</artifact>
                      </filter>
                  </filters>
                  <transformers>
                      <transformer implementation="org.apache.maven.plugins.shade.resource.ServicesResourceTransformer">
                      </transformer>
                  </transformers>
              </configuration>
              <executions>
                  <execution>
                      <phase>package</phase>
                      <goals>
                          <goal>shade</goal>
                      </goals>
                  </execution>
              </executions>
          </plugin>

  2. Select either of the following methods to connect to NebulaGraph and execute queries:

    • If only one client needs to interact with NebulaGraph, you can use the client to establish a direct connection and execute queries.

          NebulaClient client = null;
    try {
        client = NebulaClient.builder("<host>:<port>", "<username>", "<password>")
                .withAuthOptions(Collections.emptyMap())
                .withConnectTimeoutMills(1000)
                .withRequestTimeoutMills(3000)
                .build();
        client.execute("USE nba MATCH (v:player) RETURN v.id, v.name, v.score, v.gender, v.rate");
    } catch (Exception e) {
        throw e;
    } finally {
        if (client != null) {
            client.close();
        }
    }

    • If multiple clients need to interact with NebulaGraph simultaneously, you can create a connection pool to manage a set of connections. You can use the pool to get a client and return it after queries are executed.

          NebulaPool pool = null;
    try {
        pool = NebulaPool
                .builder("<host>:<port>", "<username>", "<password>")
                .withMaxClientSize(10)
                .withMinClientSize(1)
                .withConnectTimeoutMills(1000)
                .withRequestTimeoutMills(30000)
                .withBlockWhenExhausted(true)
                .withMaxWaitMills(Long.MAX_VALUE)
                .build();
        NebulaClient client = pool.getClient();
        client.execute("USE nba MATCH (v:player) RETURN v.id, v.name, v.score, v.gender, v.rate");
        pool.returnClient(client);
    } catch (Exception e) {
        throw e;
    } finally {
        if (pool != null) {
            pool.close();
        }
    }

    Replace <host>, <port>, <username>, and <password> with the actual connection information obtained from NebulaGraph Cloud.

More information