我正在尝试使用this reference guide之后的Kafka客户端启动Spring Boot应用程序，我收到以下错误。
你能告诉我如何修理吗？
@Bean
public Map<String, Object> consumerConfig() {
final HashMap<String, Object> result = new HashMap<>();
result.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, env.getProperty("spring.kafka.bootstrap.servers"));
result.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, LongDeserializer.class);
result.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, JsonDeserializer.class);
return result;
}
@Bean
public ConsumerFactory<Long, String> consumerFactory() {
return new DefaultKafkaConsumerFactory<>(consumerConfig());
}
@Bean
ConcurrentKafkaListenerContainerFactory<Long, String> kafkaListenerContainerFactory() {
ConcurrentKafkaListenerContainerFactory<Long, String> containerFactory = new ConcurrentKafkaListenerContainerFactory<>();
containerFactory.setConsumerFactory(consumerFactory());
containerFactory.setConcurrency(3);
containerFactory.getContainerProperties().setPollTimeout(3000);
return containerFactory;
}
-
org.springframework.context.ApplicationContextException: Failed to start bean 'org.springframework.kafka.config.internalKafkaListenerEndpointRegistry'; nested exception is org.apache.kafka.common.KafkaException: Failed to construct kafka consumer
at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:176) ~[spring-context-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.context.support.DefaultLifecycleProcessor.access$200(DefaultLifecycleProcessor.java:51) ~[spring-context-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.context.support.DefaultLifecycleProcessor$LifecycleGroup.start(DefaultLifecycleProcessor.java:346) ~[spring-context-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.context.support.DefaultLifecycleProcessor.startBeans(DefaultLifecycleProcessor.java:149) ~[spring-context-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.context.support.DefaultLifecycleProcessor.onRefresh(DefaultLifecycleProcessor.java:112) ~[spring-context-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:879) ~[spring-context-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:545) ~[spring-context-4.3.6.RELEASE.jar:4.3.6.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:737) [spring-boot-1.5.1.RELEASE.jar:1.5.1.RELEASE]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:370) [spring-boot-1.5.1.RELEASE.jar:1.5.1.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:314) [spring-boot-1.5.1.RELEASE.jar:1.5.1.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1162) [spring-boot-1.5.1.RELEASE.jar:1.5.1.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1151) [spring-boot-1.5.1.RELEASE.jar:1.5.1.RELEASE]
at com.ubs.wma.bmss.BmssConsumerApp.main(BmssConsumerApp.java:12) [classes/:na]
Caused by: org.apache.kafka.common.KafkaException: Failed to construct kafka consumer
at org.apache.kafka.clients.consumer.KafkaConsumer.<init>(KafkaConsumer.java:703) ~[kafka-clients-0.10.1.1.jar:na]
at org.apache.kafka.clients.consumer.KafkaConsumer.<init>(KafkaConsumer.java:553) ~[kafka-clients-0.10.1.1.jar:na]
at org.springframework.kafka.core.DefaultKafkaConsumerFactory.createKafkaConsumer(DefaultKafkaConsumerFactory.java:73) ~[spring-kafka-1.1.2.RELEASE.jar:na]
at org.springframework.kafka.core.DefaultKafkaConsumerFactory.createConsumer(DefaultKafkaConsumerFactory.java:69) ~[spring-kafka-1.1.2.RELEASE.jar:na]
at org.springframework.kafka.listener.KafkaMessageListenerContainer$ListenerConsumer.<init>(KafkaMessageListenerContainer.java:305) ~[spring-kafka-1.1.2.RELEASE.jar:na]
at org.springframework.kafka.listener.KafkaMessageListenerContainer$ListenerConsumer.<init>(KafkaMessageListenerContainer.java:230) ~[spring-kafka-1.1.2.RELEASE.jar:na]
at org.springframework.kafka.listener.KafkaMessageListenerContainer.doStart(KafkaMessageListenerContainer.java:180) ~[spring-kafka-1.1.2.RELEASE.jar:na]
at org.springframework.kafka.listener.AbstractMessageListenerContainer.start(AbstractMessageListenerContainer.java:202) ~[spring-kafka-1.1.2.RELEASE.jar:na]
at org.springframework.kafka.listener.ConcurrentMessageListenerContainer.doStart(ConcurrentMessageListenerContainer.java:124) ~[spring-kafka-1.1.2.RELEASE.jar:na]
at org.springframework.kafka.listener.AbstractMessageListenerContainer.start(AbstractMessageListenerContainer.java:202) ~[spring-kafka-1.1.2.RELEASE.jar:na]
at org.springframework.kafka.config.KafkaListenerEndpointRegistry.startIfNecessary(KafkaListenerEndpointRegistry.java:287) ~[spring-kafka-1.1.2.RELEASE.jar:na]
at org.springframework.kafka.config.KafkaListenerEndpointRegistry.start(KafkaListenerEndpointRegistry.java:236) ~[spring-kafka-1.1.2.RELEASE.jar:na]
at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:173) ~[spring-context-4.3.6.RELEASE.jar:4.3.6.RELEASE]
... 12 common frames omitted
Caused by: org.apache.kafka.common.KafkaException: Could not instantiate class org.springframework.kafka.support.serializer.JsonDeserializer
at org.apache.kafka.common.utils.Utils.newInstance(Utils.java:316) ~[kafka-clients-0.10.1.1.jar:na]
at org.apache.kafka.common.config.AbstractConfig.getConfiguredInstance(AbstractConfig.java:203) ~[kafka-clients-0.10.1.1.jar:na]
at org.apache.kafka.clients.consumer.KafkaConsumer.<init>(KafkaConsumer.java:632) ~[kafka-clients-0.10.1.1.jar:na]
... 24 common frames omitted
Caused by: java.lang.IllegalAccessException: Class org.apache.kafka.common.utils.Utils can not access a member of class org.springframework.kafka.support.serializer.JsonDeserializer with modifiers "protected"
at sun.reflect.Reflection.ensureMemberAccess(Reflection.java:102) ~[na:1.8.0_121]
at java.lang.Class.newInstance(Class.java:436) ~[na:1.8.0_121]
at org.apache.kafka.common.utils.Utils.newInstance(Utils.java:314) ~[kafka-clients-0.10.1.1.jar:na]
... 26 common frames omitted
答案 0 :(得分：7)
根据该文件，我们有：
对于更复杂或特殊情况，
KafkaConsumer以及KafkaProducer为重载构造函数提供了分别接受键和/或值的(De)Serializer个实例。为了满足此API，
DefaultKafkaProducerFactory和DefaultKafkaConsumerFactory还提供了允许将自定义(De)Serializer注入目标Producer/Consumer的属性。
进一步的Apache Kafka JavaDocs：
/**
* A producer is instantiated by providing a set of key-value pairs as configuration, a key and a value {@link Serializer}.
* Valid configuration strings are documented <a href="http://kafka.apache.org/documentation.html#producerconfigs">here</a>.
* Values can be either strings or Objects of the appropriate type (for example a numeric configuration would accept
* either the string "42" or the integer 42).
* @param configs The producer configs
* @param keySerializer The serializer for key that implements {@link Serializer}. The configure() method won't be
* called in the producer when the serializer is passed in directly.
* @param valueSerializer The serializer for value that implements {@link Serializer}. The configure() method won't
* be called in the producer when the serializer is passed in directly.
*/
public KafkaProducer(Map<String, Object> configs, Serializer<K> keySerializer, Serializer<V> valueSerializer) {
所以，你需要的是这样的：
@Bean
public ConsumerFactory<Long, String> consumerFactory() {
return new DefaultKafkaConsumerFactory<>(consumerConfig(), null, new JsonDeserializer(Foo.class));
}
JsonDeserializer无法通过反射实例化的问题，因为它需要特定的类型来反序列化。
答案 1 :(得分：-2)
您可以尝试将to.fast.xml依赖项添加到pom.xml。对于我来说，它可以解决。
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
</dependency>