20.6. Output with multipart

RESTEasy provides a simple API to output multipart data. 
package org.jboss.resteasy.plugins.providers.multipart;

public class MultipartOutput
{
   public OutputPart addPart(Object entity, MediaType mediaType)

   public OutputPart addPart(Object entity, GenericType type, MediaType mediaType)

   public OutputPart addPart(Object entity, Class type, Type genericType, MediaType mediaType)

   public List<OutputPart> getParts()

   public String getBoundary()

   public void setBoundary(String boundary)
}

public class OutputPart
{
   public MultivaluedMap<String, Object> getHeaders()

   public Object getEntity()

   public Class getType()

   public Type getGenericType()

   public MediaType getMediaType()
}
To output multipart data, create a MultipartOutput object and call addPart() methods. RESTEasy automatically finds a MessageBodyWriter to marshal your entity objects. As with MultipartInput, your marshaling may be sensitive to generic type metadata. In this case, use GenericType. The following example returns a multipart/mixed format to the calling client. The parts are JAXB-annotated Customer objects that will marshal into application/xml. 
   @Path("/multipart")
   public class MyService
   {
      @GET
      @Produces("multipart/mixed")
      public MultipartOutput get()
      {
         MultipartOutput output = new MultipartOutput();
         output.addPart(new Customer("bill"), MediaType.APPLICATION_XML_TYPE);
         output.addPart(new Customer("monica"), MediaType.APPLICATION_XML_TYPE);
         return output;
      }