Setting Uri dynamically in HTTP Location Header - spring-integration

Question

I implemented a Rest service that creates an Employee. In the response message I want to dynamically set the HTTP Location header with the newly created Employee resource Uri.
The below code is working fine and I am able to see the value in Location header as expected. However I have the Uri hardcoded in the EmpService and I want it to be dynamic. How do I extract/pass Uri information to the EmpService bean?
Config.xml
<int-http:inbound-gateway
request-channel="httpPostChannel"
reply-channel="responseChannel"
path="/emp"
supported-methods="POST"
message-converters="converters"
request-payload-type="com.samples.jaxb.Employee"/>
<int:service-activator ref="empService" method="post"
input-channel="httpPostChannel" output-channel="responseChannel"/>
EmpService.java
public Message<Employee> post (Message<Employee> msg) {
Employee emp = empDao.createEmployee(msg.getPayload());
return MessageBuilder.withPayload(emp)
.setHeader(org.springframework.http.HttpHeaders.LOCATION, "http://localhost:8080/RestSample/emp/" + emp.getEmpId())
.build();
}

Answer 1

Actually even right now your URI is dynamic:
"http://localhost:8080/RestSample/emp/" + emp.getEmpId()
OTOH you always can inject it via setter or #Value property during application start from some external property.
Or you even can do that extracting some property/header from the incoming Message.
However I guess you would like to know the host and port you are ran on.
The host you can know via InetAddress.getLocalHost().
The port you can extract via an appropriate ServletContainer vendor API, e.g. for Tomcat: Get the server port number from tomcat with out a request.
With Spring Boot you can just use #LocalServerPort:
* Annotation at the field or method/constructor parameter level that injects the HTTP
* port that got allocated at runtime. Provides a convenient alternative for
* <code>#Value("${local.server.port}")</code>.
Although... I guess this one should be enough for:
.setHeader(org.springframework.integration.http.HttpHeaders.REQUEST_URL,
request.getURI().toString())
I mean that your incoming Message after <int-http:inbound-gateway> has header set. In my test case with Spring Boot and random Tomcat port it looks like:
"http_requestUrl" -> "http://localhost:64476/service/?name=foo"