Kafka：使用 Schema Registry 序列化 Avro 消息时出错

Question

我正在尝试将我的自定义类型的 ProducerRecords 发送到 Kafka，但我收到了错误：

Caused by: org.apache.kafka.common.errors.SerializationException: Error serializing Avro message
Caused by: java.lang.IllegalArgumentException: Unsupported Avro type. Supported types are null, Boolean, Integer, Long, Float, Double, String, byte[] and IndexedRecord

我在 Schema 中设置了架构： 获取

http://localhost:8081/subjects/documentCreations-key/versions/3

回复：

{
"subject": "documentCreations-key",
"version": 3,
"id": 1,
"schema": "\"string\""}

获取

http://localhost:8081/subjects/documentCreations-value/versions/4

回应

{
"subject": "documentCreations-value",
"version": 4,
"id": 23,
"schema": "{\"type\":\"record\",\"name\":\"Document\",\"namespace\":\"com.bade\",\"fields\":[{\"name\":\"name\",\"type\":\"string\"},{\"name\":\"path\",\"type\":\"string\"}]}"

}

这是我的 Scala 课程：

class Document(val name: java.lang.String,
               val title: java.lang.String,
               val path: java.lang.String)

还有 KafkaProducer 的部分：

class MyKafkaProducer {

  val props = new Properties()
  props.put("bootstrap.servers", "localhost:9092")
  props.put("key.serializer", "io.confluent.kafka.serializers.KafkaAvroSerializer")
  props.put("value.serializer", "io.confluent.kafka.serializers.KafkaAvroSerializer")
  props.put("schema.registry.url", "http://localhost:8081")

  private val producer = new KafkaProducer[java.lang.String, Document](props)

  def sendCreateDocumentMessage(document: Document): RecordMetadata = {

    val documentRecord = new ProducerRecord[java.lang.String, Document](SharedConfig
      .documentCreationsTopic,
      document.name, document)

    producer.send(documentRecord).get()
  }

我错过了什么？我看到我可以为我的班级实施SpecificRecord，但我认为在我一直在阅读的书籍/教程中没有必要这样做。 谢谢！

已编辑：固定类名

Answer 1

回答我自己的问题。显然，（反）序列化不是自动完成的（通过反射或其他方式），但您必须从 avro 模式文件生成类。如果对某人有帮助，请发布我的pom.xml：

<build>
    <sourceDirectory>src/main/scala</sourceDirectory>
    <testSourceDirectory>src/test/scala</testSourceDirectory>

    <plugins>

        <!--force java 8-->
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.6.1</version>
            <configuration>
                <source>1.8</source>
                <target>1.8</target>
            </configuration>
        </plugin>

        <plugin>
            <groupId>net.alchim31.maven</groupId>
            <artifactId>scala-maven-plugin</artifactId>
            <version>3.3.1</version>
        </plugin>

        <plugin>
            <!-- Build an executable JAR -->
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-jar-plugin</artifactId>
            <version>3.0.2</version>
            <configuration>
                <archive>
                    <manifest>
                        <mainClass>Main</mainClass>
                    </manifest>
                </archive>
            </configuration>
        </plugin>

        <plugin>
            <groupId>org.apache.avro</groupId>
            <artifactId>avro-maven-plugin</artifactId>
            <version>${avro.version}</version>
            <executions>
                <execution>
                    <phase>generate-sources</phase>
                    <goals>
                        <goal>schema</goal>
                        <goal>protocol</goal>
                        <goal>idl-protocol</goal>
                    </goals>
                    <configuration>
                        <sourceDirectory>src/main/avro
                        </sourceDirectory>
                    </configuration>

                </execution>
            </executions>
        </plugin>
        <!--force discovery of generated classes-->
        <plugin>
            <groupId>org.codehaus.mojo</groupId>
            <artifactId>build-helper-maven-plugin</artifactId>
            <version>3.0.0</version>
            <executions>
                <execution>
                    <id>add-source</id>
                    <phase>generate-sources</phase>
                    <goals>
                        <goal>add-source</goal>
                    </goals>
                    <configuration>
                        <sources>
                            <source>target/generated-sources/avro</source>
                        </sources>
                    </configuration>
                </execution>
            </executions>
        </plugin>

    </plugins>
</build>

<repositories>
    <repository>
        <id>confluent</id>
        <url>http://packages.confluent.io/maven/</url>
    </repository>
</repositories>

<properties>
    <kafka.version>1.0.0</kafka.version>
    <confluent.version>4.0.0</confluent.version>
    <avro.version>1.8.2</avro.version>
</properties>

<dependencies>

    <dependency>
        <groupId>org.apache.kafka</groupId>
        <artifactId>kafka_2.12</artifactId>
        <version>${kafka.version}</version>
    </dependency>

    <dependency>
        <groupId>org.apache.kafka</groupId>
        <artifactId>kafka-clients</artifactId>
        <version>${kafka.version}</version>
    </dependency>

    <dependency>
        <groupId>io.confluent</groupId>
        <artifactId>kafka-avro-serializer</artifactId>
        <version>${confluent.version}</version>
    </dependency>

    <dependency>
        <groupId>org.apache.avro</groupId>
        <artifactId>avro</artifactId>
        <version>${avro.version}</version>
    </dependency>
    <dependency>
        <groupId>org.apache.avro</groupId>
        <artifactId>avro-maven-plugin</artifactId>
        <version>${avro.version}</version>
    </dependency>

</dependencies>

我使用以下 mvn 命令构建它：

mvn clean:clean avro:schema compiler:compile scala:compile jar:jar