类型不匹配:不能从Map<String、ConsumerRecords<String、Supplier>>转换为ConsumerRecords<String、Supplier>

Question

当我试图在eclipse中运行我的SupplierConsumer类时，我会得到这些错误。这是我的代码：

public class SupplierConsumer{

    public static void main(String[] args) throws Exception{

            String topicName = "SupplierTopic";
            String groupName = "SupplierTopicGroup";

            Properties props = new Properties();
            props.put("bootstrap.servers", "localhost:9092,localhost:9093");
            props.put("group.id", groupName);
            props.put("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
            props.put("value.deserializer", "SupplierDeserializer");


            KafkaConsumer<String, Supplier> consumer = new KafkaConsumer<>(props);
            consumer.subscribe(Arrays.asList(topicName));

            while (true){
                    ConsumerRecords<String, Supplier> records = consumer.poll(100);
                    for (ConsumerRecord<String, Supplier> record : records){
                            System.out.println("Supplier id= " + String.valueOf(record.value().getID()) + " Supplier  Name = " + record.value().getName() + " Supplier Start Date = " + record.value().getStartDate().toString());
                    }
            }
    }
}

1. 类型不匹配:无法从List<String>转换为String，
2. 类型不匹配:无法从Map<String,ConsumerRecords<String,Supplier>>转换为ConsumerRecords<String,Supplier>

Answer 1

我认为您在您的类路径中无意中包含了卡夫卡客户端库的一些预发布版本。我在v0.8.2-beta中找到了与编译错误相匹配的签名：

http://supergsego.com/apache/kafka/0.8.2-beta/java-doc/org/apache/kafka/clients/consumer/KafkaConsumer.html

如果您确保使用了kafka-客户端jar (v0.9或更高版本)的发行版质量版本，那么您的代码就应该编译。