For getting json response reseasy defines a way to integrate with Jackson. using reseasy-jackson-provider and resteasy-jackson2-provider.
Jackson can also be used to seralize deserialize from\to XML. i.e with jackson-jaxrs-xml-provider and jackson-dataformat-xml. But using these and producing XML response fails with
org.jboss.resteasy.core.NoMessageBodyWriterFoundFailure: Could not find MessageBodyWriter for response object of type: someclass of media type: application/xml
Dependencies used
<dependency>
<groupId>org.jboss.resteasy</groupId>
<artifactId>resteasy-jaxrs</artifactId>
<version>${resteasy.version}</version>
</dependency>
<dependency>
<groupId>org.jboss.resteasy</groupId>
<artifactId>resteasy-validator-provider-11</artifactId>
<version>${resteasy.version}</version>
</dependency>
<dependency>
<groupId>org.jboss.resteasy</groupId>
<artifactId>resteasy-servlet-initializer</artifactId>
<version>${resteasy.version}</version>
</dependency>
<dependency>
<groupId>org.jboss.resteasy</groupId>
<artifactId>resteasy-jackson2-provider</artifactId>
<version>${resteasy.version}</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.jaxrs</groupId>
<artifactId>jackson-jaxrs-xml-provider</artifactId>
<version>${jackson.version}</version>
</dependency>
Resource
@GET
@Path("/foo/{id}")
@Produces({MediaType.APPLICATION_XML})
public Foo getFoo(@PathParam("id") int id);
created https://issues.jboss.org/browse/RESTEASY-1352
lets see if it gets into resteasy artifacts.