From: Herak Sen <HSen_at_vertrax.com>
Date: Fri, 25 Sep 2009 14:16:40 -0400

1) Jersey does not provide a MessageBodyWriter for Maps. You can write a custom MessageBodyWriter.

2) JAXB- does not support Maps as top level object, so another solution is to write adaptor for Map


e.g
   MessageBodyWriter

@Provider
public class MapMessageWriter implements MessageBodyWriter<HashMap<String, String>>{

       @Override
       public long getSize(HashMap<String, String> t, Class<?> type,
                     Type genericType, Annotation[] annotations, MediaType mediaType) {
              // TODO Auto-generated method stub
              return -1;
       }

       @Override
       public boolean isWriteable(Class<?> type, Type genericType,
                     Annotation[] annotations, MediaType mediaType) {

              return mediaType.isCompatible(MediaType.APPLICATION_XML_TYPE);
       }

       @Override
       public void writeTo(HashMap<String, String> t, Class<?> type,
                     Type genericType, Annotation[] annotations, MediaType mediaType,
                     MultivaluedMap<String, Object> httpHeaders,
                     OutputStream entityStream) throws IOException,
                     WebApplicationException {

// Simple marshalling
              StringBuffer sb = new StringBuffer("<map>");
              for (Map.Entry<String, String> entry : t.entrySet()) {
                     sb.append("<entry>");
                     sb.append(" <key>").append(entry.getKey()).append("</key>");
                     sb.append(" <value>").append(entry.getValue()).append("</value>");
                     sb.append("</entry>");
              }
              sb.append("</map>");
              System.out.println(sb);
              entityStream.write(sb.toString().getBytes());
       }

}

  Adaptor

@XmlRootElement
 class Entry {
    public String key;

    public String value;

    public Entry() {}
    public Entry(Map.Entry<String,String> e) {
       key = e.getKey();
       value = e.getValue();
    }
}
@GET
@Produces("application/xml")
public List<Entry> getAttributes() {
            Map<String, String> map = new HashMap<String, String>();
            map.put("k1", "v1");
            map.put("k2", "v2");
            List<Entry> entry = new ArrayList<Entry>();
            for( Map.Entry<String,String> e : map.entrySet() )
            entry.add(new Entry(e));
            return entry;
}

Hope this helps

Herak

From: Saavedra, Gisella [mailto:gsaavedra_at_zebra.com]
Sent: Friday, September 25, 2009 12:55 PM
To: users_at_jersey.dev.java.net
Subject: [Jersey] REST service returning Map collection


Can somebody point me to an example or article, if it exists, containing a code snippet returning a Map collection, something like
@GET
@Produces({"application/xml"})
public Map<String, String> getAttributes(...) { }


just receiving a Map object at the client side, or returning an object that contains the Map?
No JSON.

I will appreciate it.

Thanks.

Gisella Saavedra
Sr. Software Engineer
gsaavedra_at_zebra.com<mailto:gsaavedra_at_zebra.com>

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