class java.lang.String cannot be cast to class java.util.List (java.lang.String and java.util.List are in module java.base of loader 'bootstrap')

huangapple
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英文:

class java.lang.String cannot be cast to class java.util.List (java.lang.String and java.util.List are in module java.base of loader 'bootstrap')

问题

Trying to use ReplyingKafkaTemplate to return the response from the service, but keep getting an error `java.lang.ClassCastException: class java.lang.String cannot be cast to class java.util.List (java.lang.String and java.util.List are in module java.base of loader 'bootstrap')`

# Listener

@KafkaListener(id = ProductTopicConstants.GET_PRODUCTS, topics = ProductTopicConstants.GET_PRODUCTS, splitIterables = false)
@SendTo
public List<Product> GetProducts(@Payload(required = false) String payload) {
    List<Product> products = _productRepository.findAll();
    return new ArrayList<>(products);
}

# KafkaConfiguration

@Configuration
public class KafkaConfiguration {
    @Bean
    public ReplyingKafkaTemplate<String, String, List<Product>> replyer(
        ProducerFactory<String, String> pf,
        ConcurrentKafkaListenerContainerFactory<String, List<Product>> containerFactory
    ) {
        containerFactory.setReplyTemplate(kafkaTemplate(pf));
        ConcurrentMessageListenerContainer<String, List<Product>> container = replyContainer(containerFactory);
        ReplyingKafkaTemplate<String, String, List<Product>> replyer = new ReplyingKafkaTemplate<>(pf, container);
        return replyer;
    }

    @Bean
    public ConcurrentMessageListenerContainer<String, List<Product>> replyContainer(
        ConcurrentKafkaListenerContainerFactory<String, List<Product>> containerFactory
    ) {
        ConcurrentMessageListenerContainer<String, List<Product>> container =
            containerFactory.createContainer(ProductTopicConstants.GET_PRODUCTS_CONTAINER);
        container.getContainerProperties().setGroupId(ProductTopicConstants.GET_PRODUCTS_CONTAINER);
        container.setBatchErrorHandler(new BatchLoggingErrorHandler());
        return container;
    }

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

    @Bean
    public NewTopic GetProducts() {
        return TopicBuilder.name(ProductTopicConstants.GET_PRODUCTS).partitions(1).replicas(1).build();
    }

    @Bean
    public NewTopic GetProductsContainer() {
        return TopicBuilder.name(ProductTopicConstants.GET_PRODUCTS_CONTAINER).partitions(1).replicas(1).build();
    }
}

# service

@Service
public class ProductProducer implements IProductProducer {
    private final ReplyingKafkaTemplate<String, String, List<Product>> _replyTemplate;
    private static final Logger LOG = LoggerFactory.getLogger(ProductProducer.class);

    public ProductProducer(ReplyingKafkaTemplate<String, String, List<Product>> replyTemplate) {
        this._replyTemplate = replyTemplate;
    }

    @Override
    public List<ProductViewModel> GetProducts() throws InterruptedException, ExecutionException, TimeoutException {
        RequestReplyFuture<String, String, List<Product>> future =
            this._replyTemplate.sendAndReceive(new ProducerRecord<>(ProductTopicConstants.GET_PRODUCTS, 0, null, null));
        LOG.info(future.getSendFuture().get(10, TimeUnit.SECONDS).getRecordMetadata().toString());
        List<Product> value = future.get(10, TimeUnit.SECONDS).value(); --> Getting an error over here 
        return List.of(new ProductViewModel("", "", 0, ""));
    }
}

# Error

Getting an error over here `List<Product> value = future.get(10, TimeUnit.SECONDS).value();`

java.lang.ClassCastException: class java.lang.String cannot be cast to class java.util.List (java.lang.String and java.util.List are in module java.base of loader 'bootstrap')
    at fete.bird.fetebirdproduct.service.producer.ProductProducer.GetProducts(ProductProducer.java:40) ~[main/:na]
    ...

(代码部分已经翻译完毕，以下内容不再包含翻译。)

英文:

Trying to use ReplyingKafkaTemplate to return the response from the service, but keep getting an error java.lang.ClassCastException: class java.lang.String cannot be cast to class java.util.List (java.lang.String and java.util.List are in module java.base of loader &#39;bootstrap&#39;)

Listener

 @KafkaListener(id = ProductTopicConstants.GET_PRODUCTS, topics = ProductTopicConstants.GET_PRODUCTS,splitIterables = false)
    @SendTo
    public List&lt;Product&gt; GetProducts(@Payload(required = false) String payload) {
        List&lt;Product&gt; products = _productRepository.findAll();
        return new ArrayList&lt;&gt;(products);
    }

KafkaConfiguration

@Configuration
public class KafkaConfiguration {
    @Bean
    public ReplyingKafkaTemplate&lt;String, String, List&lt;Product&gt;&gt; replyer(ProducerFactory&lt;String, String&gt; pf,
                                                                        ConcurrentKafkaListenerContainerFactory&lt;String, List&lt;Product&gt;&gt; containerFactory) {

        containerFactory.setReplyTemplate(kafkaTemplate(pf));
        ConcurrentMessageListenerContainer&lt;String, List&lt;Product&gt;&gt; container = replyContainer(containerFactory);
        ReplyingKafkaTemplate&lt;String, String, List&lt;Product&gt;&gt; replyer = new ReplyingKafkaTemplate&lt;&gt;(pf, container);
        return replyer;
    }

    @Bean
    public ConcurrentMessageListenerContainer&lt;String, List&lt;Product&gt;&gt; replyContainer(
            ConcurrentKafkaListenerContainerFactory&lt;String, List&lt;Product&gt;&gt; containerFactory) {

        ConcurrentMessageListenerContainer&lt;String, List&lt;Product&gt;&gt; container =
                containerFactory.createContainer(ProductTopicConstants.GET_PRODUCTS_CONTAINER);
        container.getContainerProperties().setGroupId(ProductTopicConstants.GET_PRODUCTS_CONTAINER);
        container.setBatchErrorHandler(new BatchLoggingErrorHandler());
        return container;
    }

    @Bean
    public KafkaTemplate&lt;String, String&gt; kafkaTemplate(ProducerFactory&lt;String, String&gt; pf) {
        return new KafkaTemplate&lt;&gt;(pf);
    }



   @Bean
    public NewTopic GetProducts() {
        return TopicBuilder.name(ProductTopicConstants.GET_PRODUCTS).partitions(1).replicas(1).build();
    }
    @Bean
    public NewTopic GetProductsContainer() {
        return TopicBuilder.name(ProductTopicConstants.GET_PRODUCTS_CONTAINER).partitions(1).replicas(1).build();
    }

}

service

@Service
public class ProductProducer implements IProductProducer{
  private final ReplyingKafkaTemplate&lt;String, String, List&lt;Product&gt;&gt; _replyTemplate;
    private static final Logger LOG = LoggerFactory.getLogger(ProductProducer.class);
    public ProductProducer(ReplyingKafkaTemplate&lt;String, String, List&lt;Product&gt;&gt; replyTemplate) {
        this._replyTemplate = replyTemplate;
    }

 @Override
    public List&lt;ProductViewModel&gt; GetProducts() throws InterruptedException, ExecutionException, TimeoutException {
        RequestReplyFuture&lt;String, String, List&lt;Product&gt;&gt; future =
                this._replyTemplate.sendAndReceive(new ProducerRecord&lt;&gt;(ProductTopicConstants.GET_PRODUCTS, 0, null, null));
            LOG.info(future.getSendFuture().get(10, TimeUnit.SECONDS).getRecordMetadata().toString());
            List&lt;Product&gt; value = future.get(10, TimeUnit.SECONDS).value(); --&gt; Getting an error over here 
            return List.of(new ProductViewModel(&quot;&quot;,&quot;&quot;,0,&quot;&quot;));
    }
}

Error

Getting an error over here List&lt;Product&gt; value = future.get(10, TimeUnit.SECONDS).value();

java.lang.ClassCastException: class java.lang.String cannot be cast to class java.util.List (java.lang.String and java.util.List are in module java.base of loader &#39;bootstrap&#39;)
	at fete.bird.fetebirdproduct.service.producer.ProductProducer.GetProducts(ProductProducer.java:40) ~[main/:na]
	at fete.bird.fetebirdproduct.api.v1.controller.ProductController.Products(ProductController.java:43) ~[main/:na]
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
	at java.base/java.lang.reflect.Method.invoke(Method.java:564) ~[na:na]
	at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190) ~[spring-web-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) ~[spring-web-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:879) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:793) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:634) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.36.jar:9.0.36]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
	at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
	at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
	at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.doFilterInternal(WebMvcMetricsFilter.java:93) ~[spring-boot-actuator-2.3.1.RELEASE.jar:2.3.1.RELEASE]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:373) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1590) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130) ~[na:na]
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630) ~[na:na]
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) ~[tomcat-embed-core-9.0.36.jar:9.0.36]
	at java.base/java.lang.Thread.run(Thread.java:832) ~[na:na]

Configuration

spring:
  profiles:
    active: dev
  kafka:
    bootstrapAddress: localhost:9092
    producer:
      key-serializer: org.springframework.kafka.support.serializer.JsonSerializer
      value-serializer: org.springframework.kafka.support.serializer.JsonSerializer
    consumer:
      key-deserializer: org.springframework.kafka.support.serializer.JsonDeserializer
      value-deserializer: org.springframework.kafka.support.serializer.JsonDeserializer
      auto-offset-reset: earliest
      properties:
        spring:
          json:
            trusted:
              packages: *

答案1

得分: 1

我在包名前缺少 &#39;*&#39;

    spring:
      profiles:
        active: dev
      kafka:
        bootstrapAddress: localhost:9092
        producer:
          key-serializer: org.springframework.kafka.support.serializer.JsonSerializer
          value-serializer: org.springframework.kafka.support.serializer.JsonSerializer
        consumer:
          key-deserializer: org.springframework.kafka.support.serializer.JsonDeserializer
          value-deserializer: org.springframework.kafka.support.serializer.JsonDeserializer
          auto-offset-reset: earliest
          properties:
            spring:
              json:
                trusted:
                  packages: &#39;*&#39;
英文:

I was missing '*' at the package

spring:
  profiles:
    active: dev
  kafka:
    bootstrapAddress: localhost:9092
    producer:
      key-serializer: org.springframework.kafka.support.serializer.JsonSerializer
      value-serializer: org.springframework.kafka.support.serializer.JsonSerializer
    consumer:
      key-deserializer: org.springframework.kafka.support.serializer.JsonDeserializer
      value-deserializer: org.springframework.kafka.support.serializer.JsonDeserializer
      auto-offset-reset: earliest
      properties:
        spring:
          json:
            trusted:
              packages: &#39;*&#39;

huangapple
  • 本文由 发表于 2020年7月25日 23:46:22
  • 转载请务必保留本文链接：https://java.coder-hub.com/63090326.html
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