kafka.examples.consumer.BasicConsumerExample.java Source code

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Here is the source code for kafka.examples.consumer.BasicConsumerExample.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 * <p/>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p/>
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package kafka.examples.consumer;

import net.sourceforge.argparse4j.ArgumentParsers;
import net.sourceforge.argparse4j.inf.ArgumentParser;
import net.sourceforge.argparse4j.inf.ArgumentParserException;
import net.sourceforge.argparse4j.inf.Namespace;
import org.apache.kafka.clients.consumer.ConsumerConfig;
import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.apache.kafka.clients.consumer.ConsumerRecords;
import org.apache.kafka.clients.consumer.KafkaConsumer;

import java.util.Arrays;
import java.util.Collections;
import java.util.Properties;

import static net.sourceforge.argparse4j.impl.Arguments.store;

public class BasicConsumerExample {

    public static void main(String[] args) {
        ArgumentParser parser = argParser();

        try {
            Namespace res = parser.parseArgs(args);

            /* parse args */
            String brokerList = res.getString("bootstrap.servers");
            String topic = res.getString("topic");
            String serializer = res.getString("serializer");

            Properties consumerConfig = new Properties();
            consumerConfig.put("group.id", "my-group");
            consumerConfig.put("bootstrap.servers", brokerList);
            consumerConfig.put("auto.offset.reset", "earliest");
            consumerConfig.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG,
                    "org.apache.kafka.common.serialization.ByteArrayDeserializer");
            consumerConfig.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG,
                    "org.apache.kafka.common.serialization.ByteArrayDeserializer");

            KafkaConsumer<byte[], byte[]> consumer = new KafkaConsumer<>(consumerConfig);
            consumer.subscribe(Collections.singletonList(topic));

            while (true) {
                ConsumerRecords<byte[], byte[]> records = consumer.poll(1000);
                for (ConsumerRecord<byte[], byte[]> record : records) {
                    System.out.printf(
                            "Received Message topic =%s, partition =%s, offset = %d, key = %s, value = %s\n",
                            record.topic(), record.partition(), record.offset(), deserialize(record.key()),
                            deserialize(record.value()));
                }

                consumer.commitSync();
            }

        } catch (ArgumentParserException e) {
            if (args.length == 0) {
                parser.printHelp();
                System.exit(0);
            } else {
                parser.handleError(e);
                System.exit(1);
            }
        }

    }

    private static <V> V deserialize(final byte[] objectData) {
        return (V) org.apache.commons.lang3.SerializationUtils.deserialize(objectData);
    }

    /**
     * Get the command-line argument parser.
     */
    private static ArgumentParser argParser() {
        ArgumentParser parser = ArgumentParsers.newArgumentParser("simple-producer").defaultHelp(true)
                .description("This example is to demonstrate kafka producer capabilities");

        parser.addArgument("--bootstrap.servers").action(store()).required(true).type(String.class)
                .metavar("BROKER-LIST").help("comma separated broker list");

        parser.addArgument("--topic").action(store()).required(true).type(String.class).metavar("TOPIC")
                .help("produce messages to this topic");

        parser.addArgument("--serializer").action(store()).required(false).setDefault("byte").type(String.class)
                .choices(Arrays.asList("byte", "kryo")).metavar("BYTE/KRYO")
                .help("use byte array or kryo serializer");

        return parser;
    }
}