过滤器之前的资源中没有用户代理（getAgent）

Question

I'm trying to extract user-agent in my custom filter:

public class MyFilter extends Filter {
   @Override
   protected int beforeHandle(Request request, Response response) {
      String ua = request.getClientInfo().getAgent();
   }
}

But I always get ua null .

When the request proceeds to my Resource , I do manage to extract the user-agent using the call:

String ua = getRequest().getClientInfo().getAgent();

Questions:

1. Why does it happen?
2. How can I overcome this?

Answer 1

I just did a test of your use case with version 2.3.1 of Restlet and I can't reproduce your problem. Could you give us more hints about your context.

Here is what I used.

• 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 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>org.restlet</groupId> <artifactId>restlet-user-agent</artifactId> <name>${project.artifactId}</name> <packaging>jar</packaging> <version>1.0.0-snapshot</version> <properties> <java-version>1.7</java-version> <restlet-version>2.3.1</restlet-version> </properties> <dependencies> <dependency> <groupId>org.restlet.jse</groupId> <artifactId>org.restlet</artifactId> <version>${restlet-version}</version> </dependency> </dependencies> <repositories> <repository> <id>maven-restlet</id> <name>Public online Restlet repository</name> <url>http://maven.restlet.com</url> </repository> </repositories> </project> 

• Filter

   public class MyFilter extends Filter { public MyFilter() { super(); } public MyFilter(Context context, Restlet next) { super(context, next); } public MyFilter(Context context) { super(context); } @Override protected int beforeHandle(Request request, Response response) { String ua = request.getClientInfo().getAgent(); System.out.println("[filter] ua = " + ua); return Filter.CONTINUE; } } 

• Server resource

   public class MyServerResource extends ServerResource { @Get public String test() { String ua = getRequest().getClientInfo().getAgent(); System.out.println("[server resource] ua = " + ua); return "test"; } } 

• Application

   public class RestletApplication extends Application { @Override public Restlet createInboundRoot() { Router router = new Router(getContext()); router.attach("/test", MyServerResource.class); MyFilter filter = new MyFilter(getContext(), router); return filter; } } 

Here are the traces I got using Postman in Chrome:

[filter] ua = Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/44.0.2403.130 Safari/537.36
[server resource] ua = Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/44.0.2403.130 Safari/537.36

Hope it helps you nevertheless. Thierry