How to configure consumers of queues in rabbbitmq to listen messages of more than one datatype?

I'm trying to use rabbitmq's queue for producing and consuming messages of more than one datatype. For eg. i am able to push an employee object (in json format) using jackson serializer and an String object in the queue but when i'm trying to consume the message i'm getting parse error. (ultimately i'm able to push anything but when i'm trying to consume i'm not able to).

```
**Producer code**

package com.poc.springbootrabbitmq.service;

import org.springframework.amqp.core.AmqpTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Service;

import com.poc.springbootrabbitmq.model.Employee;

@Service
public class RabbitMQSender 
{
    @Autowired
    private AmqpTemplate amqpTemplate;

    @Value("${exchangeName}")
    private String exchange;

    public void send(Employee company) 
    {
        amqpTemplate.convertAndSend(exchange,"error", company);
        amqpTemplate.convertAndSend(exchange,"error", "some String");
    }

}


**Consumer Code**



package com.rabbitmq.consumer.service;

import org.springframework.amqp.rabbit.annotation.RabbitListener;
import org.springframework.stereotype.Component;

import com.rabbitmq.consumer.model.Employee;

@Component
public class RabbitMQConsumer 
{
    @RabbitListener(queues = "${queueName}")
    public void recievedMessage(Employee employee) {
        System.out.println("Recieved Message From Queue " + employee);
    }

    @RabbitListener(queues = "${queueName}")
    public void recievedMessage1(String string) {
        System.out.println("Recieved Message From Queue " + string);
    }

}


**Employee.java**

package com.rabbitmq.consumer.model;

public class Employee {

    private String empName;
    private String empId;

    public String getEmpName() {
        return empName;
    }

    public void setEmpName(String empName) {
        this.empName = empName;
    }

    public String getEmpId() {
        return empId;
    }

    public void setEmpId(String empId) {
        this.empId = empId;
    }

    @Override
    public String toString() {
        return "Employee [empName=" + empName + ", empId=" + empId + "]";
    }

}

**My defined beans/configurations**

package com.rabbitmq.consumer.configuration;

import org.springframework.amqp.rabbit.annotation.EnableRabbit;
import org.springframework.amqp.rabbit.annotation.RabbitListenerConfigurer;
import org.springframework.amqp.rabbit.listener.RabbitListenerEndpointRegistrar;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.messaging.converter.MappingJackson2MessageConverter;
import org.springframework.messaging.handler.annotation.support.DefaultMessageHandlerMethodFactory;

@EnableRabbit
@Configuration
public class ConsumerConfiguration implements RabbitListenerConfigurer
{

    @Bean
    public MappingJackson2MessageConverter jackson2Converter() {
        MappingJackson2MessageConverter converter = new MappingJackson2MessageConverter();
        return converter;
    }

    @Bean
    public DefaultMessageHandlerMethodFactory myHandlerMethodFactory() 
    {
        DefaultMessageHandlerMethodFactory factory = new DefaultMessageHandlerMethodFactory();
        factory.setMessageConverter(jackson2Converter());
        return factory;
    }

    @Override
    public void configureRabbitListeners(RabbitListenerEndpointRegistrar registrar) 
    {
        registrar.setMessageHandlerMethodFactory(myHandlerMethodFactory());
    }

}

**ErrorLog I'm getting**

2019-04-21 20:27:31.585  WARN 5436 --- [ntContainer#0-1] s.a.r.l.ConditionalRejectingErrorHandler : Execution of Rabbit message listener failed.

org.springframework.amqp.rabbit.listener.exception.ListenerExecutionFailedException: Listener method could not be invoked with the incoming message
Endpoint handler details:
Method [public void com.rabbitmq.consumer.service.RabbitMQConsumer.recievedMessage3(com.rabbitmq.consumer.model.Employee)]
Bean [com.rabbitmq.consumer.service.RabbitMQConsumer@1457fde]
    at org.springframework.amqp.rabbit.listener.adapter.MessagingMessageListenerAdapter.invokeHandler(MessagingMessageListenerAdapter.java:193) ~[spring-rabbit-2.1.5.RELEASE.jar:2.1.5.RELEASE]
    at org.springframework.amqp.rabbit.listener.adapter.MessagingMessageListenerAdapter.onMessage(MessagingMessageListenerAdapter.java:127) ~[spring-rabbit-2.1.5.RELEASE.jar:2.1.5.RELEASE]
    at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.doInvokeListener(AbstractMessageListenerContainer.java:1552) ~[spring-rabbit-2.1.5.RELEASE.jar:2.1.5.RELEASE]
    at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.actualInvokeListener(AbstractMessageListenerContainer.java:1478) ~[spring-rabbit-2.1.5.RELEASE.jar:2.1.5.RELEASE]
    at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.invokeListener(AbstractMessageListenerContainer.java:1466) ~[spring-rabbit-2.1.5.RELEASE.jar:2.1.5.RELEASE]
    at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.doExecuteListener(AbstractMessageListenerContainer.java:1461) ~[spring-rabbit-2.1.5.RELEASE.jar:2.1.5.RELEASE]
    at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.executeListener(AbstractMessageListenerContainer.java:1410) ~[spring-rabbit-2.1.5.RELEASE.jar:2.1.5.RELEASE]
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.doReceiveAndExecute(SimpleMessageListenerContainer.java:870) [spring-rabbit-2.1.5.RELEASE.jar:2.1.5.RELEASE]
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.receiveAndExecute(SimpleMessageListenerContainer.java:854) [spring-rabbit-2.1.5.RELEASE.jar:2.1.5.RELEASE]
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.access$1600(SimpleMessageListenerContainer.java:78) [spring-rabbit-2.1.5.RELEASE.jar:2.1.5.RELEASE]
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer$AsyncMessageProcessingConsumer.mainLoop(SimpleMessageListenerContainer.java:1137) [spring-rabbit-2.1.5.RELEASE.jar:2.1.5.RELEASE]
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer$AsyncMessageProcessingConsumer.run(SimpleMessageListenerContainer.java:1043) [spring-rabbit-2.1.5.RELEASE.jar:2.1.5.RELEASE]
    at java.lang.Thread.run(Thread.java:748) [na:1.8.0_191]
Caused by: org.springframework.messaging.converter.MessageConversionException: Could not read JSON: Cannot construct instance of `com.rabbitmq.consumer.model.Employee` (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('some String')
 at [Source: (byte[])""some String""; line: 1, column: 1]; nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of `com.rabbitmq.consumer.model.Employee` (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('some String')
 at [Source: (byte[])""some String""; line: 1, column: 1]
    at org.springframework.messaging.converter.MappingJackson2MessageConverter.convertFromInternal(MappingJackson2MessageConverter.java:234) ~[spring-messaging-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.messaging.converter.AbstractMessageConverter.fromMessage(AbstractMessageConverter.java:181) ~[spring-messaging-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.messaging.handler.annotation.support.PayloadArgumentResolver.resolveArgument(PayloadArgumentResolver.java:137) ~[spring-messaging-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.messaging.handler.invocation.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:117) ~[spring-messaging-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.messaging.handler.invocation.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:147) ~[spring-messaging-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.messaging.handler.invocation.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:116) ~[spring-messaging-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.amqp.rabbit.listener.adapter.HandlerAdapter.invoke(HandlerAdapter.java:49) ~[spring-rabbit-2.1.5.RELEASE.jar:2.1.5.RELEASE]
    at org.springframework.amqp.rabbit.listener.adapter.MessagingMessageListenerAdapter.invokeHandler(MessagingMessageListenerAdapter.java:190) ~[spring-rabbit-2.1.5.RELEASE.jar:2.1.5.RELEASE]
    ... 12 common frames omitted
Caused by: com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of `com.rabbitmq.consumer.model.Employee` (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('some String')
 at [Source: (byte[])""some String""; line: 1, column: 1]
    at com.fasterxml.jackson.databind.exc.MismatchedInputException.from(MismatchedInputException.java:63) ~[jackson-databind-2.9.8.jar:2.9.8]
    at com.fasterxml.jackson.databind.DeserializationContext.reportInputMismatch(DeserializationContext.java:1343) ~[jackson-databind-2.9.8.jar:2.9.8]
    at com.fasterxml.jackson.databind.DeserializationContext.handleMissingInstantiator(DeserializationContext.java:1032) ~[jackson-databind-2.9.8.jar:2.9.8]
    at com.fasterxml.jackson.databind.deser.ValueInstantiator._createFromStringFallbacks(ValueInstantiator.java:371) ~[jackson-databind-2.9.8.jar:2.9.8]
    at com.fasterxml.jackson.databind.deser.std.StdValueInstantiator.createFromString(StdValueInstantiator.java:323) ~[jackson-databind-2.9.8.jar:2.9.8]
    at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.deserializeFromString(BeanDeserializerBase.java:1373) ~[jackson-databind-2.9.8.jar:2.9.8]
    at com.fasterxml.jackson.databind.deser.BeanDeserializer._deserializeOther(BeanDeserializer.java:171) ~[jackson-databind-2.9.8.jar:2.9.8]
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:161) ~[jackson-databind-2.9.8.jar:2.9.8]
    at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4013) ~[jackson-databind-2.9.8.jar:2.9.8]
    at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3121) ~[jackson-databind-2.9.8.jar:2.9.8]
    at org.springframework.messaging.converter.MappingJackson2MessageConverter.convertFromInternal(MappingJackson2MessageConverter.java:221) ~[spring-messaging-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    ... 19 common frames omitted

2019-04-21 20:27:31.680  WARN 5436 --- [ntContainer#0-1] ingErrorHandler$DefaultExceptionStrategy : Fatal message conversion error; message rejected; it will be dropped or routed to a dead letter exchange, if so configured: (Body:'"some String"' MessageProperties [headers={__TypeId__=java.lang.String}, contentType=application/json, contentEncoding=UTF-8, contentLength=0, receivedDeliveryMode=PERSISTENT, priority=0, redelivered=false, receivedExchange=sampleTopicExchange, receivedRoutingKey=x.y.error, deliveryTag=6, consumerTag=amq.ctag-ZlMlqxVR24vqzgAGGWE4-Q, consumerQueue=sampleTopicQueue1])
2019-04-21 20:27:31.728 ERROR 5436 --- [ntContainer#0-1] o.s.a.r.l.SimpleMessageListenerContainer : Execution of Rabbit message listener failed, and the error handler threw an exception

org.springframework.amqp.AmqpRejectAndDontRequeueException: Error Handler converted exception to fatal
    at org.springframework.amqp.rabbit.listener.ConditionalRejectingErrorHandler.handleError(ConditionalRejectingErrorHandler.java:105) ~[spring-rabbit-2.1.5.RELEASE.jar:2.1.5.RELEASE]
    at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.invokeErrorHandler(AbstractMessageListenerContainer.java:1378) [spring-rabbit-2.1.5.RELEASE.jar:2.1.5.RELEASE]
    at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.handleListenerException(AbstractMessageListenerContainer.java:1631) [spring-rabbit-2.1.5.RELEASE.jar:2.1.5.RELEASE]
    at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.executeListener(AbstractMessageListenerContainer.java:1424) [spring-rabbit-2.1.5.RELEASE.jar:2.1.5.RELEASE]
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.doReceiveAndExecute(SimpleMessageListenerContainer.java:870) [spring-rabbit-2.1.5.RELEASE.jar:2.1.5.RELEASE]
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.receiveAndExecute(SimpleMessageListenerContainer.java:854) [spring-rabbit-2.1.5.RELEASE.jar:2.1.5.RELEASE]
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.access$1600(SimpleMessageListenerContainer.java:78) [spring-rabbit-2.1.5.RELEASE.jar:2.1.5.RELEASE]
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer$AsyncMessageProcessingConsumer.mainLoop(SimpleMessageListenerContainer.java:1137) [spring-rabbit-2.1.5.RELEASE.jar:2.1.5.RELEASE]
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer$AsyncMessageProcessingConsumer.run(SimpleMessageListenerContainer.java:1043) [spring-rabbit-2.1.5.RELEASE.jar:2.1.5.RELEASE]
    at java.lang.Thread.run(Thread.java:748) [na:1.8.0_191]
Caused by: org.springframework.amqp.rabbit.listener.exception.ListenerExecutionFailedException: Listener method could not be invoked with the incoming message
Endpoint handler details:
Method [public void com.rabbitmq.consumer.service.RabbitMQConsumer.recievedMessage3(com.rabbitmq.consumer.model.Employee)]
Bean [com.rabbitmq.consumer.service.RabbitMQConsumer@1457fde]
    at org.springframework.amqp.rabbit.listener.adapter.MessagingMessageListenerAdapter.invokeHandler(MessagingMessageListenerAdapter.java:193) ~[spring-rabbit-2.1.5.RELEASE.jar:2.1.5.RELEASE]
    at org.springframework.amqp.rabbit.listener.adapter.MessagingMessageListenerAdapter.onMessage(MessagingMessageListenerAdapter.java:127) ~[spring-rabbit-2.1.5.RELEASE.jar:2.1.5.RELEASE]
    at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.doInvokeListener(AbstractMessageListenerContainer.java:1552) [spring-rabbit-2.1.5.RELEASE.jar:2.1.5.RELEASE]
    at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.actualInvokeListener(AbstractMessageListenerContainer.java:1478) [spring-rabbit-2.1.5.RELEASE.jar:2.1.5.RELEASE]
    at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.invokeListener(AbstractMessageListenerContainer.java:1466) [spring-rabbit-2.1.5.RELEASE.jar:2.1.5.RELEASE]
    at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.doExecuteListener(AbstractMessageListenerContainer.java:1461) [spring-rabbit-2.1.5.RELEASE.jar:2.1.5.RELEASE]
    at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.executeListener(AbstractMessageListenerContainer.java:1410) [spring-rabbit-2.1.5.RELEASE.jar:2.1.5.RELEASE]
    ... 6 common frames omitted
Caused by: org.springframework.messaging.converter.MessageConversionException: Could not read JSON: Cannot construct instance of `com.rabbitmq.consumer.model.Employee` (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('some String')
 at [Source: (byte[])""some String""; line: 1, column: 1]; nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of `com.rabbitmq.consumer.model.Employee` (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('some String')
 at [Source: (byte[])""some String""; line: 1, column: 1]
    at org.springframework.messaging.converter.MappingJackson2MessageConverter.convertFromInternal(MappingJackson2MessageConverter.java:234) ~[spring-messaging-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.messaging.converter.AbstractMessageConverter.fromMessage(AbstractMessageConverter.java:181) ~[spring-messaging-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.messaging.handler.annotation.support.PayloadArgumentResolver.resolveArgument(PayloadArgumentResolver.java:137) ~[spring-messaging-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.messaging.handler.invocation.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:117) ~[spring-messaging-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.messaging.handler.invocation.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:147) ~[spring-messaging-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.messaging.handler.invocation.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:116) ~[spring-messaging-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.amqp.rabbit.listener.adapter.HandlerAdapter.invoke(HandlerAdapter.java:49) ~[spring-rabbit-2.1.5.RELEASE.jar:2.1.5.RELEASE]
    at org.springframework.amqp.rabbit.listener.adapter.MessagingMessageListenerAdapter.invokeHandler(MessagingMessageListenerAdapter.java:190) ~[spring-rabbit-2.1.5.RELEASE.jar:2.1.5.RELEASE]
    ... 12 common frames omitted
Caused by: com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of `com.rabbitmq.consumer.model.Employee` (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('some String')
 at [Source: (byte[])""some String""; line: 1, column: 1]
    at com.fasterxml.jackson.databind.exc.MismatchedInputException.from(MismatchedInputException.java:63) ~[jackson-databind-2.9.8.jar:2.9.8]
    at com.fasterxml.jackson.databind.DeserializationContext.reportInputMismatch(DeserializationContext.java:1343) ~[jackson-databind-2.9.8.jar:2.9.8]
    at com.fasterxml.jackson.databind.DeserializationContext.handleMissingInstantiator(DeserializationContext.java:1032) ~[jackson-databind-2.9.8.jar:2.9.8]
    at com.fasterxml.jackson.databind.deser.ValueInstantiator._createFromStringFallbacks(ValueInstantiator.java:371) ~[jackson-databind-2.9.8.jar:2.9.8]
    at com.fasterxml.jackson.databind.deser.std.StdValueInstantiator.createFromString(StdValueInstantiator.java:323) ~[jackson-databind-2.9.8.jar:2.9.8]
    at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.deserializeFromString(BeanDeserializerBase.java:1373) ~[jackson-databind-2.9.8.jar:2.9.8]
    at com.fasterxml.jackson.databind.deser.BeanDeserializer._deserializeOther(BeanDeserializer.java:171) ~[jackson-databind-2.9.8.jar:2.9.8]
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:161) ~[jackson-databind-2.9.8.jar:2.9.8]
    at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4013) ~[jackson-databind-2.9.8.jar:2.9.8]
    at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3121) ~[jackson-databind-2.9.8.jar:2.9.8]
    at org.springframework.messaging.converter.MappingJackson2MessageConverter.convertFromInternal(MappingJackson2MessageConverter.java:221) ~[spring-messaging-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    ... 19 common frames omitted
```

Solution

@Component
public class RabbitMQConsumer 
{
    @RabbitListener(queues = "${queueName}")
    public void recievedMessage(Employee employee) {
        System.out.println("Recieved Message From Queue " + employee);
    }

    @RabbitListener(queues = "${queueName}")
    public void recievedMessage1(String string) {
        System.out.println("Recieved Message From Queue " + string);
    }

}

With that configuration, you'll get 2 listener containers which will compete for all messages, you need @RabbitListener at the class level and @RabbitHandler at the method level.

However, there is a catch-22 since the payload needs to be deserialized first so the framework can determine which method to call; we can'y infer the type from the method parameter, you have to use a Jackson2JsonMessageConverter in the container factory so it can do the conversion first, based on information in message headers.

See the documentation.