Spring Integration - Header Enricher

Reference

Pro Spring Integration - https://www.amazon.com/Pro-Spring-Integration-Experts-Voice-ebook-dp-B005PZ29OA/dp/B005PZ29OA/ref=mt_kindle?_encoding=UTF8&me=&qid= 

前篇: https://www.isaacnote.com/2018/11/spring-integration-integrate-with-tomcat.html 
下篇:Spring Integration Message Flow - Router

Enrich Header XML

1. Header-enricher 可以改變 msg 的 header, 這裡把 mykey 加入 message
2. Transformer 可以透過 @Header 或 @Headers 來取得 headers

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"

       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

       xmlns:int="http://www.springframework.org/schema/integration"

       xmlns:context="http://www.springframework.org/schema/context"

       xsi:schemaLocation="http://www.springframework.org/schema/beans

        http://www.springframework.org/schema/beans/spring-beans.xsd

        http://www.springframework.org/schema/integration

        http://www.springframework.org/schema/integration/spring-integration-5.0.xsd

        http://www.springframework.org/schema/context

        http://www.springframework.org/schema/context/spring-context-3.0.xsd">

    <context:component-scan base-package="examples"/>

    <int:header-enricher input-channel="input" output-channel="inteceptor">

        <int:header name="mykey" value="myval" />

    </int:header-enricher>

    <int:transformer input-channel="inteceptor" output-channel="output" ref="mapper" />

    <int:channel id="inteceptor" />

    <int:channel id="input"/>

    <int:channel id="output">

        <int:queue capacity="10"/>

    </int:channel>

</beans>

HeaderEnricherMain

public class HeaderEnricherMain {

    public static void main(String[] params) {

        ClassPathXmlApplicationContext ctx = new ClassPathXmlApplicationContext("classpath:HeaderEnricherMain.xml");

        MessageChannel input = ctx.getBean("input", MessageChannel.class);

        input.send(MessageBuilder.withPayload("test").build());

        PollableChannel output = ctx.getBean("output", PollableChannel.class);

        System.out.println(output.receive().getHeaders().get("mykey")); // print myval

    }

}

Transformer 用 ＠Header or @Headers 取值

@Component

public class Mapper {

    @Transformer

    public TextMessage map(Map<String, String> message) {

        System.out.println("transform from " + message + " to TextMessage");

        return new TextMessage(message.get("text"));

    }

    @Transformer

    public TextMessage map(String message) {

        System.out.println("transform from string to TextMessage");

        return new TextMessage(message);

    }

    @Transformer

    public TextMessage mapMyKey(@Header("mykey") String myval, @Headers Map<String,String> headerMap, String message) {

        System.out.println("headerMap:" + headerMap);

        return new TextMessage(myval); // myval

    }

}