kafka yml配置屬性不生效問題

查看KafkaProperties源碼：

 找到Producer類：

public static class Producer {
        private final KafkaProperties.Ssl ssl = new KafkaProperties.Ssl();
        private String acks;
        private DataSize batchSize;
        private List<String> bootstrapServers;
        private DataSize bufferMemory;
        private String clientId;
        private String compressionType;
        private Class<?> keySerializer = StringSerializer.class;
        private Class<?> valueSerializer = StringSerializer.class;
        private Integer retries;
        private String transactionIdPrefix;
        private final Map<String, String> properties = new HashMap();

        public Producer() {
        }
        。。。

 可以發現除了上面這些屬性，其他屬性沒有注入，所以yml中配置了也不生效，都是默認值；

解決辦法：

新建配置類，添加要配置的屬性，以生產者配置爲例：

@Configuration
@EnableKafka
public class KafkaConfig {

    @Value("${spring.kafka.bootstrap-servers}")
    private String kafkaHost;

    @Bean
    public ProducerFactory<String, String> producerFactory() {
        DefaultKafkaProducerFactory<String, String> producerFactory = new DefaultKafkaProducerFactory<>(producerConfigs());
        return producerFactory;
    }
    @Bean
    public Map<String, Object> producerConfigs() {
        Map<String, Object> props = new HashMap<>();
        props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, kafkaHost);
        props.put(ProducerConfig.RETRIES_CONFIG, 0);
        props.put(ProducerConfig.REQUEST_TIMEOUT_MS_CONFIG, 5000);
        props.put(ProducerConfig.LINGER_MS_CONFIG, 10);
        props.put(ProducerConfig.BUFFER_MEMORY_CONFIG, 33554432);
        props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, IntegerSerializer.class);
        props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
        props.put(ProducerConfig.MAX_BLOCK_MS_CONFIG, 10000);
        return props;
    }

    @Bean
    public KafkaTemplate<String, String> kafkaTemplate(ProducerFactory<String, String> producerFactory) {
        return new KafkaTemplate<>(producerFactory);
    }
}

這樣配置後就會生效，也就是好多同學疑惑的地方，爲啥配置文件中配置了還要再配置一遍？？？