Spring cloud stream IntegrationFlow with Rabbitmq messaging, The consumer giving ASCII numbers as message payload - spring-boot

Question

I am using spring cloud stream for messaging. In the consumer part, I used IntegrationFlow to listen to the queue. It is listening and printing the message from producer side. But the format is different that's the problem I am facing now. The content-type of the producer is application/json and the IntegrationFLow message payload showing ASCII numbers. The code is written for the consumer is given below
#EnableBinding(UserOperationConsume.class)
public class ConsumerController {
#Bean
IntegrationFlow consumerIntgrationFlow(UserOperationConsume u) {
return IntegrationFlows
.from(u.userRegistraionProduces())
//.transform(Transformers.toJson()) // not working as expected
//.transform(Transformers.fromJson(UserDTO.class))
.handle(String.class, (payload, headers) -> {
System.out.println(payload.toString()); // here the output is 123,34,105,100,34,58,49,44,34,110,97,109,101,34,58,34,86,105,115,104,110,117,34,44,34,101,109,97,105,108,34,58,34,118...
return null;
}).get();
}
}
The input interface is,
public interface UserOperationConsume {
#Input
public SubscribableChannel userRegistraionProduces();
}
And the consumer yml configuration is,
server:
port: 8181
spring:
application:
name: nets-alert-service
---
spring:
cloud:
config:
name: notification-service
uri: http://localhost:8888
---
spring:
rabbitmq:
host: localhost
port: 5672
username: guest
password: guest
---
spring:
cloud:
stream:
bindings:
userRegistraionProduces:
destination: userOperations
input:
content-type: application/json
I have tried Sink.class binding, That time I got an exact message from the queue. So please let me know if there is any mistake in this IntegrationFlow configuration. Because I am a newbie in spring cloud stream and IntegrationFlow. is there any way to transform this ascii to exact string?
Thanks in advance

Answer 1

Using IntegrationFlows.from(channel) provides no conversion hints so you just get the raw byte[] payload (containing JSON). It's not clear why you then use a toJson() transformer.
Your .handle(String.class, (payload, headers) -> {... is causing a simple ArrayToStringConverter to be used which is why you are seeing each byte value.
In any case, you are not using the framework properly. Use...
#StreamListener("userRegistraionProduces")
public void listen(UserDTO dto) {
System.out.println(dto);
}
...and the framework will take care of the conversion for you. Or...
#StreamListener("userRegistraionProduces")
public void listen(Message<UserDTO> dtoMessage) {
System.out.println(dtoMessage);
}
if your producer conveys additional information in headers.
EDIT
If you prefer to do the conversion yourself, this works fine...
#Bean
IntegrationFlow consumerIntgrationFlow(UserOperationConsume u) {
return IntegrationFlows.from(u.userRegistraionProduces())
.transform(Transformers.fromJson(UserDTO.class))
.handle((payload, headers) -> {
System.out.println(payload.toString());
return null;
}).get();
}
...since the Json transformer can read a byte[].