Generic Object Model Factory

There is an alternative way to implement object model factories by implementing the

GenericObjectModelFactory

interface which extends the ObjectModelFactory interface. Here is its definition.

package org.jboss.xml.binding;

public interface GenericObjectModelFactory
   extends ObjectModelFactory
{
   Object newChild(java.lang.Object parent,
                   org.jboss.xml.binding.ContentNavigator navigator,
                   java.lang.String namespaceURI,
                   java.lang.String localName,
                   org.xml.sax.Attributes attrs);

   void addChild(java.lang.Object parent,
                 java.lang.Object child,
                 org.jboss.xml.binding.ContentNavigator navigator,
                 java.lang.String namespaceURI,
                 java.lang.String localName);

   void setValue(java.lang.Object o,
                 org.jboss.xml.binding.ContentNavigator navigator,
                 java.lang.String namespaceURI,
                 java.lang.String localName,
                 java.lang.String value);
}

Arguments to

newChild

,

addChild

and

setValue

methods that in (direct)

ObjectModelFactory

implementation were of concrete Java types but not

java.lang.Object

are of

java.lang.Object

type in

GenericObjectModelFactory

. Implementations of

GenericObjectModelfactory

are not introspected to find

newChild

,

addChild

and

setValue

methods with arguments of concrete Java types. Instead, the three generic methods are used for all Java types and XML elements they represent.

Code example

Here is an implementation of

GenericObjectModelFactory

for book.

public class BookGenericObjectModelFactory
   implements GenericObjectModelFactory
{
   public Object newRoot(Object root,
                         ContentNavigator navigator,
                         String namespaceURI,
                         String localName,
                         Attributes attrs)
   {
      final Book book;
      if(root == null)
      {
         root = book = new Book();
      }
      else
      {
         book = (Book) root;
      }

      if(attrs.getLength() > 0)
      {
         for(int i = 0; i < attrs.getLength(); ++i)
         {
            if(attrs.getLocalName(i).equals("isbn"))
            {
               book.setIsbn(attrs.getValue(i));
            }
         }
      }

      return root;
   }

   public Object newChild(Object parent,
                          ContentNavigator navigator,
                          String namespaceURI,
                          String localName,
                          Attributes attrs)
   {
      Object child = null;
      if(parent instanceof Book)
      {
         if("character".equals(localName))
         {
            child = new BookCharacter();
         }
      }
      return child;
   }

   public void addChild(Object parent,
                        Object child,
                        ContentNavigator navigator,
                        String namespaceURI,
                        String localName)
   {
      if(parent instanceof Book)
      {
         final Book book = (Book)parent;
         if(child instanceof BookCharacter)
         {
            book.addCharacter((BookCharacter)child);
         }
      }
   }

   public void setValue(Object o, ContentNavigator navigator, String namespaceURI, String localName, String value)
   {
      if(o instanceof Book)
      {
         final Book book = (Book)o;
         if("title".equals(localName))
         {
            book.setTitle(value);
         }
         else if("author".equals(localName))
         {
            book.setAuthor(value);
         }
      }
      else if(o instanceof BookCharacter)
      {
         BookCharacter character = (BookCharacter)o;
         if("name".equals(localName))
         {
            character.setName(value);
         }
         else if("friend-of".equals(localName))
         {
            character.setFriendOf(value);
         }
         else if("since".equals(localName))
         {
            character.setSince(value);
         }
         else if("qualification".equals(localName))
         {
            character.setQualification(value);
         }
      }
   }
}

Unmarshalling client

Unmarshalling client code is the same as in the example for

ObjectModelFactory

except for one line which creates an object model factory.

      // get the XML stream
      InputStream is = new FileInputStream("resources/xml/book/" + xmlSource);

      // create unmarshaller
      Unmarshaller unmarshaller = new Unmarshaller();

      // create an instance of ObjectModelFactory
      ObjectModelFactory factory = new BookGenericObjectModelFactory();

      // let the object model factory to create an instance of Book and populate it with data from XML
      Book book = (Book)unmarshaller.unmarshal(is, factory, null);

      // close the XML stream
      is.close();