17.6. Arrays and Collections of JAXB Objects

RESTEasy automatically marshals arrays, java.util.Sets, and java.util.Lists of JAXB objects to and from XML, JSON, Fastinfoset, and other RESTEasy JAXB mappers. 
 @XmlRootElement(name = "customer")
 @XmlAccessorType(XmlAccessType.FIELD)
 public class Customer
 {
@XmlElement
private String name;

public Customer()
{
}

public Customer(String name)
{
   this.name = name;
}

public String getName()
{
   return name;
}
 }

 @Path("/")
 public class MyResource
 {
   @PUT
   @Path("array")
   @Consumes("application/xml")
   public void putCustomers(Customer[] customers)
   {
      Assert.assertEquals("bill", customers[0].getName());
      Assert.assertEquals("monica", customers[1].getName());
   }

   @GET
   @Path("set")
   @Produces("application/xml")
   public Set<Customer> getCustomerSet()
   {
      HashSet<Customer> set = new HashSet<Customer>();
      set.add(new Customer("bill"));
      set.add(new Customer("monica"));

      return set;
   }


   @PUT
   @Path("list")
   @Consumes("application/xml")
   public void putCustomers(List<Customer> customers)
   {
      Assert.assertEquals("bill", customers.get(0).getName());
      Assert.assertEquals("monica", customers.get(1).getName());
   }
 }
The resource above publishes and receives JAXB objects. We assume that these are wrapped in a collection element like the following: 
 <collection>
<customer><name>bill</name></customer>
<customer><name>monica</name></customer>
 <collection>
You can change the namespace URI, namespace tag, and collection element name by using the @org.jboss.resteasy.annotations.providers.jaxb.Wrapped annotation on a parameter or method: 
 @Target({ElementType.PARAMETER, ElementType.METHOD})
 @Retention(RetentionPolicy.RUNTIME)
 public @interface Wrapped
 {
String element() default "collection";

String namespace() default "http://jboss.org/resteasy";

String prefix() default "resteasy";
 }
So, if we wanted to output the following XML: 
 <foo:list xmlns:foo="http://foo.org">
<customer><name>bill</name></customer>
<customer><name>monica</name></customer>
 </foo:list>
We would use the @Wrapped annotation as follows: 
   @GET
   @Path("list")
   @Produces("application/xml")
   @Wrapped(element="list", namespace="http://foo.org", prefix="foo")
   public List<Customer> getCustomerSet()
   {
      List<Customer> list = new ArrayList<Customer>();
      list.add(new Customer("bill"));
      list.add(new Customer("monica"));

      return list;
   }

17.6.1. JSON and JAXB Collections/Arrays

RESTEasy supports using collections with JSON. It encloses lists, sets, or arrays of returned JAXB objects in a simple JSON array. For example: 
   @XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
public static class Foo
{
   @XmlAttribute
   private String test;

   public Foo()
   {
   }

   public Foo(String test)
   {
      this.test = test;
   }

   public String getTest()
   {
      return test;
   }

   public void setTest(String test)
   {
      this.test = test;
   }
}
A List or Array of the Foo class would be represented in JSON like so: 
 [{"foo":{"@test":"bill"}},{"foo":{"@test":"monica}"}}]
It would also expect this format when receiving input.