Spring integration: @Payload: Extract the payload in POJO methods

@Payload annotation binds a method parameter to the payload of a message.

 

Example

@ServiceActivator(inputChannel = "printChannel")
public void consumeStringMessage(@Payload String msg, @Header("msgId") String msgId) {
	System.out.println("Received message from printChannel : " + msg);
	System.out.println("Message id : " + msgId);

}

 

Find the below working application.

 

Step 1: Create new maven project ‘extract-payload-and-header-demo’.

 

Step 2: Update pom.xml with maven dependencies.

 

pom.xml

 

<project xmlns="http://maven.apache.org/POM/4.0.0"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.sample.app</groupId>
	<artifactId>extract-payload-and-header-demo</artifactId>
	<version>1</version>

	<!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-parent -->
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.4.0</version>
	</parent>

	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-integration</artifactId>
		</dependency>

	</dependencies>

</project>

Step 3: Define Service activator.

 

PrintService.java

package com.sample.app.service;

import org.springframework.integration.annotation.ServiceActivator;
import org.springframework.messaging.handler.annotation.Header;
import org.springframework.messaging.handler.annotation.Payload;
import org.springframework.stereotype.Component;

@Component
public class PrintService {

	@ServiceActivator(inputChannel = "printChannel")
	public void consumeStringMessage(@Payload String msg, @Header("msgId") String msgId) {
		System.out.println("Received message from printChannel : " + msg);
		System.out.println("Message id : " + msgId);

	}

}

Step 4: Define gateway.

 

CustomGateway.java

package com.sample.app.gateway;

import org.springframework.integration.annotation.Gateway;
import org.springframework.integration.annotation.MessagingGateway;
import org.springframework.messaging.Message;

@MessagingGateway
public interface CustomGateway {

	@Gateway(requestChannel = "printChannel")
	public void print(Message<String> message);

}

Step 5: Define main application class.

 

App.java

package com.sample.app;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.integration.support.MessageBuilder;
import org.springframework.messaging.Message;

import com.sample.app.gateway.CustomGateway;

@SpringBootApplication
@Configuration
public class App {
	@Autowired
	private CustomGateway customGateway;

	public static void main(String[] args) {
		SpringApplication.run(App.class, args);
	}

	@Bean
	public CommandLineRunner demo() {
		return (args) -> {

			Message<String> msg = MessageBuilder.withPayload("india is a beautiful country")
					.setHeader("msgId", "id-123").setHeader("tag", "test").build();

			customGateway.print(msg);
		};

	};

}

Total project structure looks like below.

Run App.java, you will see below messages in console.

 

Received message from printChannel : india is a beautiful country

Message id : id-123

 

You can download complete working application from below link.

https://github.com/harikrishna553/springboot/tree/master/spring-integration/extract-payload-and-header-demo

 

  

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