Kafka学习笔记-Java简单操作

wfkjxy · 发表于 2017-6-2 08:29:55

　　Maven依赖包：

[plain] view plain copy

<dependency>
<groupId>org.apache.kafka</groupId>
<artifactId>kafka-clients</artifactId>
<version>0.8.2.1</version>
</dependency>
<dependency>
<groupId>org.apache.kafka</groupId>
<artifactId>kafka_2.11</artifactId>
<version>0.8.2.1</version>
</dependency>

　　
代码如下：

[java] view plain copy

import java.util.Properties;
import org.apache.kafka.clients.producer.Callback;
import org.apache.kafka.clients.producer.KafkaProducer;
import org.apache.kafka.clients.producer.ProducerRecord;
import org.apache.kafka.clients.producer.RecordMetadata;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class KafkaProducerTest {
private static final Logger LOG = LoggerFactory.getLogger(KafkaProducerTest.class);
private static Properties properties = null;
static {
properties = new Properties();
properties.put("bootstrap.servers", "centos.master:9092,centos.slave1:9092,centos.slave2:9092");
properties.put("producer.type", "sync");
properties.put("request.required.acks", "1");
properties.put("serializer.class", "kafka.serializer.DefaultEncoder");
properties.put("partitioner.class", "kafka.producer.DefaultPartitioner");
properties.put("key.serializer", "org.apache.kafka.common.serialization.ByteArraySerializer");
// properties.put("key.serializer", "org.apache.kafka.common.serialization.StringSerializer");
properties.put("value.serializer", "org.apache.kafka.common.serialization.ByteArraySerializer");
// properties.put("value.serializer", "org.apache.kafka.common.serialization.StringSerializer");
}
public void produce() {
KafkaProducer<byte[], byte[]> kafkaProducer = new KafkaProducer<byte[],byte[]>(properties);
ProducerRecord<byte[],byte[]> kafkaRecord = new ProducerRecord<byte[],byte[]>(
"test", "kkk".getBytes(), "vvv".getBytes());
kafkaProducer.send(kafkaRecord, new Callback() {
public void onCompletion(RecordMetadata metadata, Exception e) {
if(null != e) {
LOG.info("the offset of the send record is {}", metadata.offset());
LOG.error(e.getMessage(), e);
}
LOG.info("complete!");
}
});
kafkaProducer.close();
}
public static void main(String[] args) {
KafkaProducerTest kafkaProducerTest = new KafkaProducerTest();
for (int i = 0; i < 10; i++) {
kafkaProducerTest.produce();
}
}
}

[java] view plain copy

import java.util.List;
import java.util.Map;
import java.util.Properties;
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 org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class KafkaConsumerTest {
private static final Logger LOG = LoggerFactory.getLogger(KafkaConsumerTest.class);
public static void main(String[] args) {
Properties properties = new Properties();
properties.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG,
"centos.master:9092,centos.slave1:9092,centos.slave2:9092");
properties.put(ConsumerConfig.GROUP_ID_CONFIG, "test-consumer-group");
properties.put(ConsumerConfig.SESSION_TIMEOUT_MS, "1000");
properties.put(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG, "true");
properties.put(ConsumerConfig.PARTITION_ASSIGNMENT_STRATEGY, "range");
// properties.put(ConsumerConfig.PARTITION_ASSIGNMENT_STRATEGY, "roundrobin");
properties.put(ConsumerConfig.AUTO_COMMIT_INTERVAL_MS_CONFIG, "10000");
properties.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG,
"org.apache.kafka.common.serialization.ByteArrayDeserializer");
properties.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG,
"org.apache.kafka.common.serialization.ByteArrayDeserializer");
KafkaConsumer<byte[], byte[]> kafkaConsumer = new KafkaConsumer<byte[], byte[]>(properties);
kafkaConsumer.subscribe("test");
// kafkaConsumer.subscribe("*");
boolean isRunning = true;
while(isRunning) {
Map<String, ConsumerRecords<byte[], byte[]>> results = kafkaConsumer.poll(100);
if (null != results) {
for (Map.Entry<String, ConsumerRecords<byte[], byte[]>> entry : results.entrySet()) {
LOG.info("topic {}", entry.getKey());
ConsumerRecords<byte[], byte[]> consumerRecords = entry.getValue();
List<ConsumerRecord<byte[], byte[]>> records = consumerRecords.records();
for (int i = 0, len = records.size(); i < len; i++) {
ConsumerRecord<byte[], byte[]> consumerRecord = records.get(i);
LOG.info("topic {} partition {}", consumerRecord.topic(), consumerRecord.partition());
try {
LOG.info("offset {} value {}", consumerRecord.offset(), new String(consumerRecord.value()));
} catch (Exception e) {
LOG.error(e.getMessage(), e);
}
}
}
}
}
kafkaConsumer.close();
}
}

　　发现KafkaConsumer的poll方法未实现

[java] view plain copy

@Override
public Map<String, ConsumerRecords<K,V>> poll(long timeout) {
// TODO Auto-generated method stub
return null;
}

　　
后改为kafka.javaapi.consumer.SimpleConsumer实现，正常运行

[java] view plain copy

import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import kafka.api.FetchRequest;
import kafka.api.FetchRequestBuilder;
import kafka.api.PartitionOffsetRequestInfo;
import kafka.cluster.Broker;
import kafka.common.ErrorMapping;
import kafka.common.TopicAndPartition;
import kafka.javaapi.FetchResponse;
import kafka.javaapi.OffsetRequest;
import kafka.javaapi.OffsetResponse;
import kafka.javaapi.PartitionMetadata;
import kafka.javaapi.TopicMetadata;
import kafka.javaapi.TopicMetadataRequest;
import kafka.javaapi.TopicMetadataResponse;
import kafka.javaapi.consumer.SimpleConsumer;
import kafka.message.MessageAndOffset;
public class KafkaSimpleConsumerTest {
private List<String> borkerList = new ArrayList<String>();
public KafkaSimpleConsumerTest() {
borkerList = new ArrayList<String>();
}
public static void main(String args[]) {
KafkaSimpleConsumerTest kafkaSimpleConsumer = new KafkaSimpleConsumerTest();
// 最大读取消息数量
long maxReadNum = Long.parseLong("3");
// 订阅的topic
String topic = "test";
// 查找的分区
int partition = Integer.parseInt("0");
// broker节点
List<String> seeds = new ArrayList<String>();
seeds.add("centos.master");
seeds.add("centos.slave1");
seeds.add("centos.slave2");
// 端口
int port = Integer.parseInt("9092");
try {
kafkaSimpleConsumer.run(maxReadNum, topic, partition, seeds, port);
} catch (Exception e) {
System.out.println("Oops:" + e);
e.printStackTrace();
}
}
public void run(long maxReadNum, String topic, int partition, List<String> seedBrokers, int port) throws Exception {
// 获取指定topic partition的元数据
PartitionMetadata metadata = findLeader(seedBrokers, port, topic, partition);
if (metadata == null) {
System.out.println("can't find metadata for topic and partition. exit");
return;
}
if (metadata.leader() == null) {
System.out.println("can't find leader for topic and partition. exit");
return;
}
String leadBroker = metadata.leader().host();
String clientName = "client_" + topic + "_" + partition;
SimpleConsumer consumer = new SimpleConsumer(leadBroker, port, 100000, 64 * 1024, clientName);
long readOffset = getLastOffset(consumer, topic, partition, kafka.api.OffsetRequest.EarliestTime(), clientName);
int numErrors = 0;
while (maxReadNum > 0) {
if (consumer == null) {
consumer = new SimpleConsumer(leadBroker, port, 100000, 64 * 1024, clientName);
}
FetchRequest req = new FetchRequestBuilder().clientId(clientName).addFetch(topic, partition, readOffset, 100000).build();
FetchResponse fetchResponse = consumer.fetch(req);
if (fetchResponse.hasError()) {
numErrors++;
short code = fetchResponse.errorCode(topic, partition);
System.out.println("error fetching data from the broker:" + leadBroker + " reason: " + code);
if (numErrors > 5)
break;
if (code == ErrorMapping.OffsetOutOfRangeCode()) {
readOffset = getLastOffset(consumer, topic, partition, kafka.api.OffsetRequest.LatestTime(), clientName);
continue;
}
consumer.close();
consumer = null;
leadBroker = findNewLeader(leadBroker, topic, partition, port);
continue;
}
numErrors = 0;
long numRead = 0;
for (MessageAndOffset messageAndOffset : fetchResponse.messageSet(topic, partition)) {
long currentOffset = messageAndOffset.offset();
if (currentOffset < readOffset) {
System.out.println("found an old offset: " + currentOffset + " expecting: " + readOffset);
continue;
}
readOffset = messageAndOffset.nextOffset();
ByteBuffer payload = messageAndOffset.message().payload();
byte[] bytes = new byte[payload.limit()];
payload.get(bytes);
System.out.println(String.valueOf(messageAndOffset.offset()) + ": " + new String(bytes, "UTF-8"));
numRead++;
maxReadNum--;
}
if (numRead == 0) {
try {
Thread.sleep(1000);
} catch (InterruptedException ie) {
}
}
}
if (consumer != null)
consumer.close();
}
/**
* 从活跃的Broker列表中找出指定Topic、Partition中的Leader Broker
* @param seedBrokers
* @param port
* @param topic
* @param partition
* @return
*/
private PartitionMetadata findLeader(List<String> seedBrokers, int port, String topic, int partition) {
PartitionMetadata partitionMetadata = null;
loop: for (String seedBroker : seedBrokers) {
SimpleConsumer consumer = null;
try {
consumer = new SimpleConsumer(seedBroker, port, 100000, 64 * 1024, "leaderLookup");
List<String> topics = Collections.singletonList(topic);
TopicMetadataRequest topicMetadataRequest = new TopicMetadataRequest(topics);
TopicMetadataResponse topicMetadataResponse = consumer.send(topicMetadataRequest);
List<TopicMetadata> topicMetadatas = topicMetadataResponse.topicsMetadata();
for (TopicMetadata topicMetadata : topicMetadatas) {
for (PartitionMetadata pMetadata : topicMetadata.partitionsMetadata()) {
if (pMetadata.partitionId() == partition) {
partitionMetadata = pMetadata;
break loop;
}
}
}
} catch (Exception e) {
System.out.println("error communicating with broker [" + seedBroker + "] to find leader for [" + topic + ", " + partition + "] reason: " + e);
} finally {
if (consumer != null)
consumer.close();
}
}
if (partitionMetadata != null) {
borkerList.clear();
for (Broker replica : partitionMetadata.replicas()) {
borkerList.add(replica.host());
}
}
return partitionMetadata;
}
public static long getLastOffset(SimpleConsumer consumer, String topic, int partition, long whichTime, String clientName) {
TopicAndPartition topicAndPartition = new TopicAndPartition(topic, partition);
Map<TopicAndPartition, PartitionOffsetRequestInfo> requestInfo = new HashMap<TopicAndPartition, PartitionOffsetRequestInfo>();
requestInfo.put(topicAndPartition, new PartitionOffsetRequestInfo(whichTime, 1));
OffsetRequest request = new OffsetRequest(requestInfo, kafka.api.OffsetRequest.CurrentVersion(), clientName);
OffsetResponse response = consumer.getOffsetsBefore(request);
if (response.hasError()) {
System.out.println("error fetching data offset data the broker. reason: " + response.errorCode(topic, partition));
return 0;
}
long[] offsets = response.offsets(topic, partition);
return offsets[0];
}
private String findNewLeader(String oldLeader, String topic, int partition, int port) throws Exception {
for (int i = 0; i < 3; i++) {
boolean goToSleep = false;
PartitionMetadata metadata = findLeader(borkerList, port, topic, partition);
if (metadata == null) {
goToSleep = true;
} else if (metadata.leader() == null) {
goToSleep = true;
} else if (oldLeader.equalsIgnoreCase(metadata.leader().host()) && i == 0) {
goToSleep = true;
} else {
return metadata.leader().host();
}
if (goToSleep) {
try {
Thread.sleep(1000);
} catch (InterruptedException ie) {
}
}
}
System.out.println("unable to find new leader after broker failure. exit");
throw new Exception("unable to find new leader after broker failure. exit");
}
}

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