Jay*_*ram 37 java apache-kafka apache-zookeeper
我想通过java在Kafka(kafka_2.8.0-0.8.1.1)中创建一个主题.如果我在命令提示符下创建一个主题,并且如果我通过java api推送消息,它工作正常.但我想通过java api创建一个主题.经过长时间的搜索,我发现下面的代码,
ZkClient zkClient = new ZkClient("localhost:2181", 10000, 10000);
AdminUtils.createTopic(zkClient, myTopic, 10, 1, new Properties());
我尝试了上面的代码,它显示主题已创建,但我无法在主题中推送消息.我的代码中有什么问题吗？或者以其他任何方式实现上述目标？
Jay*_*ram 39
我修好了..经过长时间的研究......
ZkClient zkClient = new ZkClient("localhost:2181", 10000, 10000);
AdminUtils.createTopic(zkClient, myTopic, 10, 1, new Properties());
从上面的代码中,ZkClient将创建一个主题,但是这个主题信息将无法识别kafka.所以我们要做的是,我们需要以下列方式为ZkClient创建对象,
首先导入以下声明,
import kafka.utils.ZKStringSerializer$;
并按以下方式为ZkClient创建对象,
ZkClient zkClient = new ZkClient("localhost:2181", 10000, 10000, ZKStringSerializer$.MODULE$);
AdminUtils.createTopic(zkClient, myTopic, 10, 1, new Properties());
由于api已被更改,上面的代码不适用于kafka> 0.9,使用以下代码为kafka> 0.9
import java.util.Properties;
import kafka.admin.AdminUtils;
import kafka.utils.ZKStringSerializer$;
import kafka.utils.ZkUtils;
import org.I0Itec.zkclient.ZkClient;
import org.I0Itec.zkclient.ZkConnection;
public class KafkaTopicCreationInJava
{
public static void main(String[] args) throws Exception {
ZkClient zkClient = null;
ZkUtils zkUtils = null;
try {
String zookeeperHosts = "192.168.20.1:2181"; // If multiple zookeeper then -> String zookeeperHosts = "192.168.20.1:2181,192.168.20.2:2181";
int sessionTimeOutInMs = 15 * 1000; // 15 secs
int connectionTimeOutInMs = 10 * 1000; // 10 secs
zkClient = new ZkClient(zookeeperHosts, sessionTimeOutInMs, connectionTimeOutInMs, ZKStringSerializer$.MODULE$);
zkUtils = new ZkUtils(zkClient, new ZkConnection(zookeeperHosts), false);
String topicName = "testTopic";
int noOfPartitions = 2;
int noOfReplication = 3;
Properties topicConfiguration = new Properties();
AdminUtils.createTopic(zkUtils, topicName, noOfPartitions, noOfReplication, topicConfiguration);
} catch (Exception ex) {
ex.printStackTrace();
} finally {
if (zkClient != null) {
zkClient.close();
}
}
}
}
在最新的（2.1.0）API中，该过程似乎已大大简化。使用适用于Kafka 2.1.0的最新API，可以按以下步骤进行操作
import org.apache.kafka.clients.admin.AdminClient;
import org.apache.kafka.clients.admin.CreateTopicsResult;
import org.apache.kafka.clients.admin.NewTopic;
Properties properties = new Properties();
properties.load(new FileReader(new File("kafka.properties")));
AdminClient adminClient = AdminClient.create(properties);
NewTopic newTopic = new NewTopic("topicName", 1, (short)1); //new NewTopic(topicName, numPartitions, replicationFactor)
List<NewTopic> newTopics = new ArrayList<NewTopic>();
newTopics.add(newTopic);
adminClient.createTopics(newTopics);
adminClient.close();
kafka.properties文件的内容如下
bootstrap.servers=localhost:9092
group.id=test
enable.auto.commit=true
auto.commit.interval.ms=1000
key.deserializer=org.apache.kafka.common.serialization.StringDeserializer
value.deserializer=org.apache.kafka.common.serialization.StringDeserializer
请注意，必须关闭AdminClient的实例才能反映新创建的主题。
只是指向任何使用Kafka更新版本查看此内容的人(在撰写本文时,我使用的是Kafka v0.10.0.0).
你必须改变;
AdminUtils.createTopic(zkUtils, topicName, noOfPartitions, noOfReplications, topicConfiguration);
以下;
AdminUtils.createTopic(zkUtils, topicName, noOfPartitions, noOfReplications, true, Enforced$.MODULE$);
完成后关闭连接也是个好主意;
zkClient.close();
对于那些试图在kafka v0.10.2.1中实现这一目的并遇到序列化错误的问题' java.io.StreamCorruptedException: invalid stream header: 3139322E'以下是带有必要导入的示例工作代码.
import org.I0Itec.zkclient.ZkClient;
import org.I0Itec.zkclient.ZkConnection;
import org.I0Itec.zkclient.exception.ZkMarshallingError;
import org.I0Itec.zkclient.serialize.ZkSerializer;
import org.apache.kafka.clients.consumer.KafkaConsumer;
import org.apache.kafka.common.PartitionInfo;
import kafka.admin.AdminUtils;
import kafka.admin.RackAwareMode;
import kafka.utils.ZKStringSerializer;
import kafka.utils.ZkUtils;
public static void createTopic(String topicName, int numPartitions, int numReplication) {
ZkClient zkClient = null;
ZkUtils zkUtils = null;
try {
String zookeeperHosts = "199.98.916.902:2181"; // If multiple zookeeper then -> String zookeeperHosts = "192.168.20.1:2181,192.168.20.2:2181";
int sessionTimeOutInMs = 15 * 1000; // 15 secs
int connectionTimeOutInMs = 10 * 1000; // 10 secs
zkClient = new ZkClient(zookeeperHosts, sessionTimeOutInMs, connectionTimeOutInMs);
//Ref: https://gist.github.com/jjkoshy/3842975
zkClient.setZkSerializer(new ZkSerializer() {
@Override
public byte[] serialize(Object o) throws ZkMarshallingError {
return ZKStringSerializer.serialize(o);
}
@Override
public Object deserialize(byte[] bytes) throws ZkMarshallingError {
return ZKStringSerializer.deserialize(bytes);
}
});
zkUtils = new ZkUtils(zkClient, new ZkConnection(zookeeperHosts), false);
int noOfPartitions = 2;
int noOfReplication = 3;
Properties topicConfiguration = new Properties();
AdminUtils.createTopic(zkUtils, topicName, noOfPartitions, noOfReplication, topicConfiguration,
RackAwareMode.Enforced$.MODULE$);
} catch (Exception ex) {
ex.printStackTrace();
} finally {
if (zkClient != null) {
zkClient.close();
}
}
}
AdminUtils API已弃用。有一个新的API AdminZkClient，我们可以使用它来管理Kafka服务器中的主题。
String zookeeperHost = "127.0.0.1:2181";
Boolean isSucre = false;
int sessionTimeoutMs = 200000;
int connectionTimeoutMs = 15000;
int maxInFlightRequests = 10;
Time time = Time.SYSTEM;
String metricGroup = "myGroup";
String metricType = "myType";
KafkaZkClient zkClient = KafkaZkClient.apply(zookeeperHost,isSucre,sessionTimeoutMs,
connectionTimeoutMs,maxInFlightRequests,time,metricGroup,metricType);
AdminZkClient adminZkClient = new AdminZkClient(zkClient);
String topicName1 = "myTopic";
int partitions = 3;
int replication = 1;
Properties topicConfig = new Properties();
adminZkClient.createTopic(topicName1,partitions,replication,
topicConfig,RackAwareMode.Disabled$.MODULE$);
您可以参考此链接以获取详细信息：https : //www.analyticshut.com/streaming-services/kafka/create-and-list-kafka-topics-in-java/