Question

我试图创建一个简单的程序来从kafka主题打印Kstream。我不断获得NPE，完全没有想法。

我使用了spring cloud-stream-binder-kafka-streams依赖，我正在使用最新版本的spring cloud＆＃34; Finchley.M9＆＃34;。

我写的代码是：

@Component
@EnableBinding(KafkaStreamsProcessor.class)
public class EventListener{

    @StreamListener("input")
    public void listen(KStream<String,String> kstream){
        kstream.print();
    }
}

application.properties具有：

spring.cloud.stream.bindings.input.destination=slot-events
spring.cloud.stream.kafka.streams.binder.configuration.default.key.serde=org.apache.kafka.common.serialization.Serdes$StringSerde
spring.cloud.stream.kafka.streams.binder.configuration.default.value.serde=org.apache.kafka.common.serialization.Serdes$StringSerde
spring.cloud.stream.kafka.streams.binder.configuration.key.serde=org.apache.kafka.common.serialization.Serdes$StringSerde
spring.cloud.stream.kafka.streams.binder.configuration.value.serde=org.apache.kafka.common.serialization.Serdes$StringSerde
spring.cloud.stream.kafka.binder.keySerde=org.apache.kafka.common.serialization.Serdes$StringSerde
spring.cloud.stream.kafka.binder.valueSerde=org.apache.kafka.common.serialization.Serdes$StringSerde
spring.cloud.stream.kafka.streams.binder.configuration.commit.interval.ms=1000
spring.cloud.stream.kafka.streams.binder.configuration.applicationId=listener
spring.cloud.stream.kafka.streams.binder.configuration.zookeeper.connect=localhost:2181

当我启动服务时，我在控制台上一直收到以下错误：

018-03-31 22:57:52.641  INFO 26301 --- [           main] sStreamListenerSetupMethodOrchestrator$1 :  values:
        application.id = default
        application.server =
        bootstrap.servers = [localhost:9092]
        buffered.records.per.partition = 1000
        cache.max.bytes.buffering = 10485760
        client.id =
        commit.interval.ms = 1000
        connections.max.idle.ms = 540000
        default.deserialization.exception.handler = class org.apache.kafka.streams.errors.LogAndFailExceptionHandler
        default.key.serde = class org.apache.kafka.common.serialization.Serdes$StringSerde
        default.timestamp.extractor = class org.apache.kafka.streams.processor.FailOnInvalidTimestamp
        default.value.serde = class org.apache.kafka.common.serialization.Serdes$StringSerde
        key.serde = class org.apache.kafka.common.serialization.Serdes$StringSerde
        metadata.max.age.ms = 300000
        metric.reporters = []
        metrics.num.samples = 2
        metrics.recording.level = INFO
        metrics.sample.window.ms = 30000
        num.standby.replicas = 0
        num.stream.threads = 1
        partition.grouper = class org.apache.kafka.streams.processor.DefaultPartitionGrouper
        poll.ms = 100
        processing.guarantee = at_least_once
        receive.buffer.bytes = 32768
        reconnect.backoff.max.ms = 1000
        reconnect.backoff.ms = 50
        replication.factor = 1
        request.timeout.ms = 40000
        retry.backoff.ms = 100
        rocksdb.config.setter = null
        security.protocol = PLAINTEXT
        send.buffer.bytes = 131072
        state.cleanup.delay.ms = 600000
        state.dir = /tmp/kafka-streams
        timestamp.extractor = null
        value.serde = class org.apache.kafka.common.serialization.Serdes$StringSerde
        windowstore.changelog.additional.retention.ms = 86400000
        zookeeper.connect = localhost:2181

2018-03-31 22:57:52.656  INFO 26301 --- [           main] o.apache.catalina.core.StandardService   : Stopping service [Tomcat]
2018-03-31 22:57:52.685  INFO 26301 --- [           main] ConditionEvaluationReportLoggingListener :

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2018-03-31 22:57:52.693 ERROR 26301 --- [           main] o.s.boot.SpringApplication               : Application run failed

java.lang.IllegalStateException: java.lang.NullPointerException
        at org.springframework.cloud.stream.binder.kafka.streams.KafkaStreamsStreamListenerSetupMethodOrchestrator.adaptAndRetrieveInboundArguments(KafkaStreamsStreamListenerSetupMethodOrchestrator.java:273) ~[spring-cloud-stream-binder-kafka-streams-2.0.0.RC3.jar!/:2.0.0.RC3]
        at org.springframework.cloud.stream.binder.kafka.streams.KafkaStreamsStreamListenerSetupMethodOrchestrator.orchestrateStreamListenerSetupMethod(KafkaStreamsStreamListenerSetupMethodOrchestrator.java:154) ~[spring-cloud-stream-binder-kafka-streams-2.0.0.RC3.jar!/:2.0.0.RC3]
        at org.springframework.cloud.stream.binding.StreamListenerAnnotationBeanPostProcessor.doPostProcess(StreamListenerAnnotationBeanPostProcessor.java:195) ~[spring-cloud-stream-2.0.0.RC3.jar!/:2.0.0.RC3]
        at org.springframework.cloud.stream.binding.StreamListenerAnnotationBeanPostProcessor.lambda$postProcessAfterInitialization$0(StreamListenerAnnotationBeanPostProcessor.java:167) ~[spring-cloud-stream-2.0.0.RC3.jar!/:2.0.0.RC3]
        at java.lang.Iterable.forEach(Iterable.java:75) ~[na:1.8.0_161]
        at org.springframework.cloud.stream.binding.StreamListenerAnnotationBeanPostProcessor.injectAndPostProcessDependencies(StreamListenerAnnotationBeanPostProcessor.java:285) ~[spring-cloud-stream-2.0.0.RC3.jar!/:2.0.0.RC3]
        at org.springframework.cloud.stream.binding.StreamListenerAnnotationBeanPostProcessor.afterSingletonsInstantiated(StreamListenerAnnotationBeanPostProcessor.java:105) ~[spring-cloud-stream-2.0.0.RC3.jar!/:2.0.0.RC3]
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:777) ~[spring-beans-5.0.4.RELEASE.jar!/:5.0.4.RELEASE]
        at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:868) ~[spring-context-5.0.4.RELEASE.jar!/:5.0.4.RELEASE]
        at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:549) ~[spring-context-5.0.4.RELEASE.jar!/:5.0.4.RELEASE]
        at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140) ~[spring-boot-2.0.0.RELEASE.jar!/:2.0.0.RELEASE]
        at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:752) [spring-boot-2.0.0.RELEASE.jar!/:2.0.0.RELEASE]
        at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:388) [spring-boot-2.0.0.RELEASE.jar!/:2.0.0.RELEASE]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:327) [spring-boot-2.0.0.RELEASE.jar!/:2.0.0.RELEASE]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1246) [spring-boot-2.0.0.RELEASE.jar!/:2.0.0.RELEASE]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1234) [spring-boot-2.0.0.RELEASE.jar!/:2.0.0.RELEASE]
        at dg.athena.sideprojects.kafkastreampoc.KafkastreampocApplication.main(KafkastreampocApplication.java:15) [classes!/:na]
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_161]
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_161]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_161]
        at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_161]
        at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:48) [kafkastreampoc-0.0.1-SNAPSHOT.jar:na]
        at org.springframework.boot.loader.Launcher.launch(Launcher.java:87) [kafkastreampoc-0.0.1-SNAPSHOT.jar:na]
        at org.springframework.boot.loader.Launcher.launch(Launcher.java:50) [kafkastreampoc-0.0.1-SNAPSHOT.jar:na]
        at org.springframework.boot.loader.JarLauncher.main(JarLauncher.java:51) [kafkastreampoc-0.0.1-SNAPSHOT.jar:na]
Caused by: java.lang.NullPointerException: null
        at org.springframework.cloud.stream.binder.kafka.streams.KafkaStreamsStreamListenerSetupMethodOrchestrator.getkStream(KafkaStreamsStreamListenerSetupMethodOrchestrator.java:294) ~[spring-cloud-stream-binder-kafka-streams-2.0.0.RC3.jar!/:2.0.0.RC3]
        at org.springframework.cloud.stream.binder.kafka.streams.KafkaStreamsStreamListenerSetupMethodOrchestrator.adaptAndRetrieveInboundArguments(KafkaStreamsStreamListenerSetupMethodOrchestrator.java:235) ~[spring-cloud-stream-binder-kafka-streams-2.0.0.RC3.jar!/:2.0.0.RC3]
        ... 24 common frames omitted

有人可以建议吗？

Answer 1

这是在最新快照中修复的错误。您可以尝试将活页夹升级到1.0.0.BUILD-SNAPSHOT并重试吗？

Answer 2

使用Spring Starter或Spring Initializr时，包括Spring Cloud Stream在内的Gradle（或Maven）依赖项

testImplementation 'org.springframework.cloud: spring-cloud-stream-test-support'

每次执行“ bootrun”以启动应用程序时，都会生成NPE或非法状态异常。

注释掉上述Gradle依赖性时，NPE消失并且一切正常。使用Spring Cloud Stream和Kafka Streams在超过六个不同的spring boot应用程序上重复了这一步骤。

当前假设一切正常，因为代码在消除测试依赖的情况下运行良好。但是，永远不要在不理解问题的情况下继续进行（因为它们以后可能会再次困扰）。

任何想法/修正都值得赞赏。

使用Kstream与spring cloud stream和kafka 1.0.1

2 个答案: