发送到kafka主题时序列化消息时出错

vql8enpb 于 2021-06-07 发布在 Kafka

关注(0)|答案(3)|浏览(543)

我需要测试一个消息，其中包含头，所以我需要使用messagebuilder，但我不能序列化。
我尝试在producer道具上添加序列化设置，但没有成功。
有人能帮我吗？
此错误：

org.apache.kafka.common.errors.SerializationException: Can't convert value of class org.springframework.messaging.support.GenericMessage to class org.apache.kafka.common.serialization.StringSerializer specified in value.serializer

我的测试类：

public class TransactionMastercardAdapterTest extends AbstractTest{

@Autowired
private KafkaTemplate<String, Message<String>> template;

@ClassRule
public static KafkaEmbedded embeddedKafka = new KafkaEmbedded(1);

@BeforeClass
public static void setUp() {
    System.setProperty("spring.kafka.bootstrap-servers", embeddedKafka.getBrokersAsString());
    System.setProperty("spring.cloud.stream.kafka.binder.zkNodes", embeddedKafka.getZookeeperConnectionString());
}

@Test
public void sendTransactionCommandTest(){

    String payload = "{\"o2oTransactionId\" : \"" + UUID.randomUUID().toString().toUpperCase() + "\","
            + "\"cardId\" : \"11\","
            + "\"transactionId\" : \"20110405123456\","
            + "\"amount\" : 200.59,"
            + "\"partnerId\" : \"11\"}";

    Map<String, Object> props = KafkaTestUtils.producerProps(embeddedKafka);
    props.put("key.serializer", "org.apache.kafka.common.serialization.StringSerializer");
    props.put("value.serializer", "org.apache.kafka.common.serialization.StringSerializer");

    Producer<String, Message<String>> producer = new KafkaProducer<>(props);
    producer.send(new ProducerRecord<String, Message<String>> ("notification_topic", MessageBuilder.withPayload(payload)
            .setHeader("status", "RECEIVED")
            .setHeader("service", "MASTERCARD")
            .build()));

    Map<String, Object> configs = KafkaTestUtils.consumerProps("test1", "false", embeddedKafka);

    configs.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
    ConsumerFactory<byte[], byte[]> cf = new DefaultKafkaConsumerFactory<>(configs);

    Consumer<byte[], byte[]> consumer = cf.createConsumer();
    consumer.subscribe(Collections.singleton("transaction_topic"));
    ConsumerRecords<byte[], byte[]> records = consumer.poll(10_000);
    consumer.commitSync();

    assertThat(records.count()).isEqualTo(1);
}

}

apache-kafka kafka-producer-api spring-kafka spring-cloud-stream

来源：https://stackoverflow.com/questions/43612072/error-to-serialize-message-when-sending-to-kafka-topic

3条答案

按热度按时间

8wtpewkr1#

我想说错误是显而易见的：

Can't convert value of class org.springframework.messaging.support.GenericMessage to class org.apache.kafka.common.serialization.StringSerializer specified in value.serializer

你的价值在哪里 GenericMessage ，但是 StringSerializer 只能使用字符串。
你需要的是 JavaSerializer 不存在，但不难写：

public class JavaSerializer implements Serializer<Object> {

    @Override
    public byte[] serialize(String topic, Object data) {
        try {
            ByteArrayOutputStream byteStream = new ByteArrayOutputStream();
            ObjectOutputStream objectStream = new ObjectOutputStream(byteStream);
            objectStream.writeObject(data);
            objectStream.flush();
            objectStream.close();
            return byteStream.toByteArray();
        }
        catch (IOException e) {
            throw new IllegalStateException("Can't serialize object: " + data, e);
        }
    }

    @Override
    public void configure(Map<String, ?> configs, boolean isKey) {

    }

    @Override
    public void close() {

    }

}

并对此进行配置 value.serializer 财产。

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a14dhokn2#

private void configureProducer() {
Properties props = new Properties();
props.put("key.serializer",
        "org.apache.kafka.common.serialization.StringSerializer");
props.put("value.serializer",
        "org.apache.kafka.common.serialization.ByteArraySerializer");

producer = new KafkaProducer<String, String>(props);

}
这就行了。

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zdwk9cvp3#

为json类添加注解 @XmlRootElement

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