无法反序列化实例 Kafka 流

Question

我做错了什么，我下面的kafka流程序在流式传输数据时出现问题，"无法从令牌中反序列化com.kafka.productiontest.models.TimeOff的实例START_ARRAY"。

我有一个主题 timeOffs2，其中包含具有键 timeOffID 的超时信息，值是包含 employeeId 的对象类型。我只想将所有休假时间分组为员工密钥并写信给商店。

对于存储密钥，将是 employeeId，值将是超时列表。

程序属性和流式处理逻辑：

public Properties getKafkaProperties() throws UnknownHostException {
InetAddress myHost = InetAddress.getLocalHost();
Properties kafkaStreamProperties = new Properties();
kafkaStreamProperties.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapServers);
kafkaStreamProperties.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG, Serdes.String().getClass());
kafkaStreamProperties.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG, TimeOffSerde.class);
kafkaStreamProperties.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.StringSerializer");
kafkaStreamProperties.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, "com.kafka.productiontest.models.TimeOffSerializer");
kafkaStreamProperties.put(StreamsConfig.APPLICATION_ID_CONFIG, application_id );
kafkaStreamProperties.put(StreamsConfig.APPLICATION_SERVER_CONFIG, myHost.getHostName() + ":" + port);
return kafkaStreamProperties;
}

String topic = "timeOffs2";
StreamsBuilder builder = new StreamsBuilder();
KStream<String, TimeOff> source = builder.stream(topic);
KTable<String, ArrayList<TimeOff>> newStore = source.groupBy((k, v) -> v.getEmployeeId())
.aggregate(ArrayList::new,
(key, value, aggregate) -> {
aggregate.add(value);
return aggregate;
}, Materialized.as("NewStore").withValueSerde(TimeOffListSerde(TimeOffSerde)));
final Topology topology = builder.build();
final KafkaStreams streams = new KafkaStreams(topology, getKafkaProperties());

TimeOffSerializer.java

ackage com.kafka.productiontest.models;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.apache.kafka.common.serialization.Serializer;
import java.util.Map;
public class TimeOffSerializer implements Serializer  {
@Override
public void configure(Map configs, boolean isKey) {
}
@Override
public byte[] serialize(String topic, Object data) {
byte[] retVal = null;
ObjectMapper objectMapper = new ObjectMapper();
try {
retVal = objectMapper.writeValueAsString(data).getBytes();
} catch (Exception e) {
e.printStackTrace();
}
return retVal;
}
@Override
public void close() {
}
}

时间关闭反序列化程序.java

package com.kafka.productiontest.models;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.apache.kafka.common.serialization.Deserializer ;
import java.util.Map;
public class TimeOffDeserializer implements Deserializer {
@Override
public void configure(Map configs, boolean isKey) {
}
@Override
public TimeOff deserialize(String arg0, byte[] arg1) {
ObjectMapper mapper = new ObjectMapper();
TimeOff timeOff = null;
try {
timeOff = mapper.readValue(arg1, TimeOff.class);
} catch (Exception e) {
e.printStackTrace();
}
return timeOff;
}
@Override
public void close() {
}
}

时间离开塞尔德.java

package com.kafka.productiontest.models;
import org.apache.kafka.common.serialization.Deserializer;
import org.apache.kafka.common.serialization.Serde;
import org.apache.kafka.common.serialization.Serdes;
import org.apache.kafka.common.serialization.Serializer;
import java.util.Map;
public class TimeOffSerde implements Serde<Object> {
private final Serde inner;
public TimeOffSerde(){
inner = Serdes.serdeFrom(new TimeOffSerializer(), new TimeOffDeserializer());
}
@Override
public void configure(Map<String, ?> configs, boolean isKey) {
inner.serializer().configure(configs, isKey);
inner.deserializer().configure(configs, isKey);
}
@Override
public void close() {
inner.serializer().close();
inner.deserializer().close();
}
@Override
public Serializer<Object> serializer() {
return inner.serializer();
}
@Override
public Deserializer<Object> deserializer() {
return inner.deserializer();
}
}

TimeOffListSerializer.java

package com.kafka.productiontest.models;
import org.apache.kafka.common.serialization.Serializer;
import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.sql.Time;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.Map;
public class TimeOffListSerializer implements Serializer<ArrayList<TimeOff>> {
private Serializer<TimeOff> inner;
public TimeOffListSerializer(Serializer<TimeOff> inner) {
this.inner = inner;
}
@Override
public void configure(Map<String, ?> configs, boolean isKey) {
}
@Override
public byte[] serialize(String topic, ArrayList<TimeOff> data) {
final int size = data.size();
final ByteArrayOutputStream baos = new ByteArrayOutputStream();
final DataOutputStream dos = new DataOutputStream(baos);
final Iterator<TimeOff> iterator = data.iterator();
try {
dos.writeInt(size);
while (iterator.hasNext()) {
final byte[] bytes = inner.serialize(topic, iterator.next());
dos.writeInt(bytes.length);
dos.write(bytes);
}
}catch (Exception ex) {
}
return baos.toByteArray();
}
@Override
public void close() {
inner.close();
}
}

TimeOffList反序列化程序.java

package com.kafka.productiontest.models;
import org.apache.kafka.common.serialization.Deserializer;
import java.io.ByteArrayInputStream;
import java.io.DataInputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Map;
public class TimeOffListDeserializer  implements Deserializer<ArrayList<TimeOff>> {
private final Deserializer<TimeOff> valueDeserializer;
public TimeOffListDeserializer(final Deserializer<TimeOff> valueDeserializer) {
this.valueDeserializer = valueDeserializer;
}
@Override
public void configure(Map<String, ?> configs, boolean isKey) {
}
@Override
public ArrayList<TimeOff> deserialize(String topic, byte[] data)  {
if (data == null || data.length == 0) {
return null;
}
final ArrayList<TimeOff> arrayList = new ArrayList<>();
final DataInputStream dataInputStream = new DataInputStream(new ByteArrayInputStream(data));
try {
final int records = dataInputStream.readInt();
for (int i = 0; i < records; i++) {
final byte[] valueBytes = new byte[dataInputStream.readInt()];
dataInputStream.read(valueBytes);
arrayList.add(valueDeserializer.deserialize(topic, valueBytes));
}
} catch (IOException e) {
throw new RuntimeException("Unable to deserialize ArrayList", e);
}
return arrayList;
}
@Override
public void close() {
}
}

TimeOffListSerde.java

package com.kafka.productiontest.models;
import org.apache.kafka.common.serialization.Deserializer;
import org.apache.kafka.common.serialization.Serde;
import org.apache.kafka.common.serialization.Serdes;
import org.apache.kafka.common.serialization.Serializer;
import java.util.ArrayList;
import java.util.Map;
public class TimeOffListSerde implements Serde<ArrayList<TimeOff>> {
private Serde<ArrayList<TimeOff>> inner;
public TimeOffListSerde() {
}
public TimeOffListSerde(Serde<TimeOff> serde){
inner = Serdes.serdeFrom(new TimeOffListSerializer(serde.serializer()), new TimeOffListDeserializer(serde.deserializer()));
}
@Override
public void configure(Map<String, ?> configs, boolean isKey) {
inner.serializer().configure(configs, isKey);
inner.deserializer().configure(configs, isKey);
}
@Override
public void close() {
inner.serializer().close();
inner.deserializer().close();
}
@Override
public Serializer<ArrayList<TimeOff>> serializer() {
return inner.serializer();
}
@Override
public Deserializer<ArrayList<TimeOff>> deserializer() {
return inner.deserializer();
}
}

我认为问题出在ValueSerde的这一部分。我无法使用此代码进行编译。但是如果我使用 ValueSerde 删除，它会给我这个问题"无法反序列化 TimeOff 对象"。你能帮助和指导我做错了什么吗？

KTable<String, ArrayList<TimeOff>> newStore = source.groupBy((k, v) -> v.getEmployeeId())
.aggregate(ArrayList::new,
(key, value, aggregate) -> {
aggregate.add(value);
return aggregate;
}, Materialized.as("NewStore").withValueSerde(TimeOffListSerde(TimeOffSerde)));

Answer 1

查看您的代码，我可以看到几个问题：

1. TimeOffSerde - 它应该实现Serde<TimeOff>而不是Serde<Object>
2. 您不会在Materialized中传递键和值的类型，因此它假定它是Object

因此，您的流媒体部分应该是这样的：

KTable<String, ArrayList<TimeOff>> newStore = source.groupBy((k, v) -> v.getEmployeeId())
.aggregate(ArrayList::new,
(key, value, aggregate) -> {
aggregate.add(value);
return aggregate;
}, Materialized.<String, ArrayList<TimeOff>, KeyValueStore<Bytes, byte[]>>as("NewStore").withValueSerde(new TimeOffListSerde(new TimeOffSerde())));

注意：Rember 在修改后清除状态存储目录。