问题
I want to implement Kafka Consumer and Producer which sends and receives Java Objects. Full Source I tried this:
Producer:
@Configuration
public class KafkaProducerConfig {
@Value(value = "${kafka.bootstrapAddress}")
private String bootstrapAddress;
@Bean
public ProducerFactory<String, SaleRequestFactory> saleRequestFactoryProducerFactory() {
Map<String, Object> configProps = new HashMap<>();
configProps.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapAddress);
configProps.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
configProps.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, SaleRequestFactorySerializer.class);
return new DefaultKafkaProducerFactory<>(configProps);
}
@Bean
public ProducerFactory<String, String> producerFactory() {
Map<String, Object> configProps = new HashMap<>();
configProps.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapAddress);
return new DefaultKafkaProducerFactory<>(configProps);
}
@Bean
public KafkaTemplate<String, SaleRequestFactory> saleRequestFactoryKafkaTemplate() {
return new KafkaTemplate<>(saleRequestFactoryProducerFactory());
}
@Bean
public KafkaTemplate<String, String> kafkaTemplate() {
return new KafkaTemplate<>(producerFactory());
}
@Bean
public ReplyingKafkaTemplate<String, SaleRequestFactory, SaleResponseFactory> replyKafkaTemplate(ProducerFactory<String, SaleRequestFactory> producerFactory, ConcurrentKafkaListenerContainerFactory<String, SaleResponseFactory> factory) {
ConcurrentMessageListenerContainer<String, SaleResponseFactory> kafkaMessageListenerContainer = factory.createContainer("tp-sale");
kafkaMessageListenerContainer.getContainerProperties().setGroupId("tp-sale.reply");
return new ReplyingKafkaTemplate<>(producerFactory, kafkaMessageListenerContainer);
}
}
Send object:
@RestController
@RequestMapping("/checkout")
public class CheckoutController {
private TransactionService transactionService;
private KafkaTemplate<String, SaleRequestFactory> saleRequestFactoryKafkaTemplate;
private ReplyingKafkaTemplate<String, SaleRequestFactory, SaleResponseFactory> requestReplyKafkaTemplate;
private static String topic = "tp-sale";
@Autowired
public CheckoutController(ValidationMessage validationMessage, TransactionService transactionService,
KafkaTemplate<String, SaleRequestFactory> saleRequestFactoryKafkaTemplate,
ReplyingKafkaTemplate<String, SaleRequestFactory, SaleResponseFactory> requestReplyKafkaTemplate){
this.transactionService = transactionService;
this.saleRequestFactoryKafkaTemplate = saleRequestFactoryKafkaTemplate;
this.requestReplyKafkaTemplate = requestReplyKafkaTemplate;
}
@PostMapping("test")
private void performPayment() throws ExecutionException, InterruptedException, TimeoutException {
Transaction transaction = new Transaction();
transaction.setStatus(PaymentTransactionStatus.IN_PROGRESS.getText());
Transaction insertedTransaction = transactionService.save(transaction);
SaleRequestFactory obj = new SaleRequestFactory();
obj.setId(100);
ProducerRecord<String, SaleRequestFactory> record = new ProducerRecord<>("tp-sale", obj);
RequestReplyFuture<String, SaleRequestFactory, SaleResponseFactory> replyFuture = requestReplyKafkaTemplate.sendAndReceive(record);
SendResult<String, SaleRequestFactory> sendResult = replyFuture.getSendFuture().get(10, TimeUnit.SECONDS);
ConsumerRecord<String, SaleResponseFactory> consumerRecord = replyFuture.get(10, TimeUnit.SECONDS);
SaleResponseFactory value = consumerRecord.value();
System.out.println("!!!!!!!!!!!! " + value.getUnique_id());
}
}
Consumer:
@EnableKafka
@Configuration
public class KafkaConsumerConfig {
@Value(value = "${kafka.bootstrapAddress}")
private String bootstrapAddress;
private String groupId = "test";
@Bean
public ConsumerFactory<String, SaleResponseFactory> consumerFactory() {
Map<String, Object> props = new HashMap<>();
props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapAddress);
props.put(ConsumerConfig.GROUP_ID_CONFIG, groupId);
props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, SaleResponseFactoryDeserializer.class);
return new DefaultKafkaConsumerFactory<>(props);
}
@Bean
public ConcurrentKafkaListenerContainerFactory<String, SaleResponseFactory> kafkaListenerContainerFactory() {
ConcurrentKafkaListenerContainerFactory<String, SaleResponseFactory> factory =
new ConcurrentKafkaListenerContainerFactory<>();
factory.setConsumerFactory(consumerFactory());
return factory;
}
}
Receive Object
@Component
public class ProcessingSaleListener {
private static String topic = "tp-sale";
@KafkaListener(topics = "tp-sale")
public SaleResponseFactory process(@Payload SaleRequestFactory tf, @Headers MessageHeaders headers) throws Exception {
System.out.println(tf.getId());
SaleResponseFactory resObj = new SaleResponseFactory();
resObj.setUnique_id("123123");
return resObj;
}
}
Custom objects
import java.io.Serializable;
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;
@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
@Builder(toBuilder = true)
public class SaleRequestFactory implements Serializable {
private static final long serialVersionUID = 1744050117179344127L;
private int id;
}
Serializer
import org.apache.kafka.common.serialization.Serializer;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.io.Serializable;
public class SaleRequestFactorySerializer implements Serializable, Serializer<SaleRequestFactory> {
@Override
public byte[] serialize(String topic, SaleRequestFactory data)
{
ByteArrayOutputStream out = new ByteArrayOutputStream();
try
{
ObjectOutputStream outputStream = new ObjectOutputStream(out);
outputStream.writeObject(data);
out.close();
}
catch (IOException e)
{
throw new RuntimeException("Unhandled", e);
}
return out.toByteArray();
}
}
Response Object
import java.io.Serializable;
import java.time.LocalDateTime;
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;
@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
@Builder(toBuilder = true)
public class SaleResponseFactory implements Serializable {
private static final long serialVersionUID = 1744050117179344127L;
private String unique_id;
}
Response Class
import org.apache.kafka.common.serialization.Deserializer;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.Serializable;
public class SaleResponseFactoryDeserializer implements Serializable, Deserializer<SaleRequestFactory> {
@Override
public SaleRequestFactory deserialize(String topic, byte[] data)
{
SaleRequestFactory saleRequestFactory = null;
try
{
ByteArrayInputStream bis = new ByteArrayInputStream(data);
ObjectInputStream in = new ObjectInputStream(bis);
saleRequestFactory = (SaleRequestFactory) in.readObject();
in.close();
}
catch (IOException | ClassNotFoundException e)
{
throw new RuntimeException("Unhandled", e);
}
return saleRequestFactory;
}
}
When I send some message I get error:
23:52:08.920 [consumer-0-C-1] DEBUG KafkaMessageListenerContainer$ListenerConsumer[debug:313] - Commit list: {tp-sale-0=OffsetAndMetadata{offset=35, leaderEpoch=null, metadata=''}}
23:52:08.920 [consumer-0-C-1] DEBUG KafkaMessageListenerContainer$ListenerConsumer[debug:313] - Committing: {tp-sale-0=OffsetAndMetadata{offset=35, leaderEpoch=null, metadata=''}}
23:52:08.926 [http-nio-8090-exec-4] DEBUG OpenEntityManagerInViewInterceptor[afterCompletion:111] - Closing JPA EntityManager in OpenEntityManagerInViewInterceptor
23:52:08.928 [http-nio-8090-exec-4] DEBUG DispatcherServlet[logResult:1101] - Failed to complete request: java.lang.ClassCastException: class java.lang.String cannot be cast to class org.engine.plugin.transactions.factory.SaleResponseFactory (java.lang.String is in module java.base of loader 'bootstrap'; org.engine.plugin.transactions.factory.SaleResponseFactory is in unnamed module of loader org.springframework.boot.loader.LaunchedURLClassLoader @6267c3bb)
23:52:08.928 [http-nio-8090-exec-4] DEBUG HstsHeaderWriter[writeHeaders:169] - Not injecting HSTS header since it did not match the requestMatcher org.springframework.security.web.header.writers.HstsHeaderWriter$SecureRequestMatcher@2cfd2bb6
23:52:08.928 [http-nio-8090-exec-4] DEBUG HttpSessionSecurityContextRepository[saveContext:351] - SecurityContext is empty or contents are anonymous - context will not be stored in HttpSession.
23:52:08.928 [http-nio-8090-exec-4] DEBUG SecurityContextPersistenceFilter[doFilter:119] - SecurityContextHolder now cleared, as request processing completed
23:52:08.929 [http-nio-8090-exec-4] ERROR [dispatcherServlet][log:175] - Servlet.service() for servlet [dispatcherServlet] in context with path [/engine] threw exception [Request processing failed; nested exception is java.lang.ClassCastException: class java.lang.String cannot be cast to class org.engine.plugin.transactions.factory.SaleResponseFactory (java.lang.String is in module java.base of loader 'bootstrap'; org.engine.plugin.transactions.factory.SaleResponseFactory is in unnamed module of loader org.springframework.boot.loader.LaunchedURLClassLoader @6267c3bb)] with root cause
java.lang.ClassCastException: class java.lang.String cannot be cast to class org.engine.plugin.transactions.factory.SaleResponseFactory (java.lang.String is in module java.base of loader 'bootstrap'; org.engine.plugin.transactions.factory.SaleResponseFactory is in unnamed module of loader org.springframework.boot.loader.LaunchedURLClassLoader @6267c3bb)
at org.engine.rest.CheckoutController.performPayment(CheckoutController.java:95)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:567)
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:878)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:792)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:652)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:320)
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:126)
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:90)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:118)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:137)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:111)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:158)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:63)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:116)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
at org.springframework.security.web.header.HeaderWriterFilter.doHeadersAfter(HeaderWriterFilter.java:92)
at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:77)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:105)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:56)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:215)
at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:178)
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:358)
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:271)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.doFilterInternal(WebMvcMetricsFilter.java:93)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.springframework.web.filter.CorsFilter.doFilterInternal(CorsFilter.java:92)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:143)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:374)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1590)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.base/java.lang.Thread.run(Thread.java:835)
Do you know how I can fix this issue?
来源：https://stackoverflow.com/questions/64961034/classcastexception-class-java-lang-string-cannot-be-cast-to-class-saleresponsef