Java使用pulsar-flink-connector读取pulsar catalog元数据代码剖析

简介

通过 pulsar-flink-connector 读取到 Apache pulsar 中的namespaces、topics的元数据信息。
pulsar-flink-connector 的 github： https://github.com/streamnative/pulsar-flink

Maven

 <dependency>
   <groupId>io.streamnative.connectors</groupId>
   <artifactId>pulsar-flink-connector-2.11-1.12</artifactId>
   <version>2.7.3</version>
 </dependency>

   <!-- JAR repositories -->
   <repositories>
        <repository>
            <id>central</id>
            <layout>default</layout>
            <url>https://repo1.maven.org/maven2</url>
        </repository>
        <repository>
            <id>bintray-streamnative-maven</id>
            <name>bintray</name>
            <url>https://dl.bintray.com/streamnative/maven</url>
        </repository>
    </repositories>

CODE

使用PulsarMetadataReader获取元数据

package com.levi.demo;

import org.apache.flink.streaming.connectors.pulsar.internal.PulsarMetadataReader;
import org.apache.pulsar.client.admin.PulsarAdminException;
import org.apache.pulsar.client.impl.auth.AuthenticationToken;
import org.apache.pulsar.client.impl.conf.ClientConfigurationData;
import org.apache.pulsar.common.schema.SchemaInfo;
import org.apache.pulsar.common.schema.SchemaType;

import java.io.IOException;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * Test.
 *
 * @author levi
 * @version 1.0
 **/
public class Test {

    public static void main(String[] args)  {
        final ClientConfigurationData configurationData = new ClientConfigurationData();
        configurationData.setServiceUrl("pulsar://127.0.0.1:6650");
        //Your Pulsar Token
        final AuthenticationToken token =
                new AuthenticationToken(
                        "eyJxxxxxxxxxxx.eyxxxxxxxxxxxxx.xxxxxxxxxxx");
        configurationData.setAuthentication(token);

        try (final PulsarMetadataReader reader =
                     new PulsarMetadataReader("http://127.0.0.1:8443",
                             configurationData,
                             "",
                             new HashMap(),
                             -1,
                             -1)) {
            //获取namespaces
            final List<String> namespaces = reader.listNamespaces();
            System.out.println("namespaces: " + namespaces.toString());

            for (final String namespace : namespaces) {
                //获取Topics
                final List<String> topics = reader.getTopics(namespace);
                System.out.println("topic: " + topics.toString());

                for (String topic : topics) {
                    //获取字段SchemaInfo
                    final SchemaInfo schemaInfo = reader.getPulsarSchema(topic);
                    final String name = schemaInfo.getName();
                    System.out.println("SchemaName:" + name); //topicName
                    final SchemaType type = schemaInfo.getType();
                    System.out.println("SchemaType:" + type.toString());// "JSON"...
                    final Map<String, String> properties = schemaInfo.getProperties();
                    System.out.println(properties);
                    final String schemaDefinition = schemaInfo.getSchemaDefinition();
                    System.out.println(schemaDefinition); // Field info.
                }
            }

        } catch (IOException | PulsarAdminException e) {
            e.printStackTrace();
        }

    }

}

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