javolution.xml

Class XMLFormat<T>

java.lang.Object

javolution.xml.XMLFormat<T>

public abstract class XMLFormat<T>
extends java.lang.Object

This class represents the format base class for XML serialization and deserialization.

Application classes typically define a default XML format for their instances using protected static XMLFormat class members. Formats are inherited by sub-classes. For example:

     public abstract class Graphic implements XMLSerializable {
         private boolean _isVisible;
         private Paint _paint; // null if none.
         private Stroke _stroke; // null if none.
         private Transform _transform; // null if none.

         // XML format with positional associations (members identified by their position),
         // see XML package description for examples of name associations.
         protected static final XMLFormat<Graphic> GRAPHIC_XML = new XMLFormat<Graphic>(Graphic.class) {
              public void write(Graphic g, OutputElement xml) {
                  xml.setAttribute("isVisible", g._isVisible);
                  xml.add(g._paint); // First.
                  xml.add(g._stroke); // Second.
                  xml.add(g._transform); // Third.
              }
              public void read(InputElement xml, Graphic g) {
                  g._isVisible = xml.getAttribute("isVisible", true);
                  g._paint = xml.getNext();
                  g._stroke = xml.getNext();
                  g._transform = xml.getNext();
                  return g;
             }
         };
    }

Due to the sequential nature of XML serialization/deserialization, formatting/parsing of XML attributes should always be performed before formatting/parsing of the XML content.

The mapping between classes and XML formats can be overriden through XMLBinding instances. Here is an example of serialization/deserialization:

     // Creates a list holding diverse objects.
     List list = new ArrayList();
     list.add("John Doe");
     list.add(null);
     Map map = new FastMap();
     map.put("ONE", 1);
     map.put("TWO", 2);
     list.add(map);

     // Use of custom binding.
     XMLBinding binding = new XMLBinding();
     binding.setAlias(FastMap.class, "Map");
     binding.setAlias(String.class, "String");
     binding.setAlias(Integer.class, "Integer");

     // Formats the list to XML .
     OutputStream out = new FileOutputStream("C:/list.xml");
     XMLObjectWriter writer = new XMLObjectWriter().setOutput(out).setBinding(binding);
     writer.write(list, "MyList", ArrayList.class);
     writer.close();

Here is the output list.xml document produced:

     <MyList>
         <String value="John Doe"/>
         <Null/>
         <Map>
             <Key class="String" value="ONE"/>
             <Value class="Integer" value="1"/>
             <Key class="String" value="TWO"/>
             <Value class="Integer" value="2"/>
         </Map>
     </MyList>

The list can be read back with the following code:

     // Reads back to a FastTable instance.
     InputStream in = new FileInputStream("C:/list.xml");
     XMLObjectReader reader = new XMLObjectReader().setInput(in).setBinding(binding);
     FastTable table = reader.read("MyList", FastTable.class);
     reader.close();

Note: Any type for which a text format is known can be represented as a XML attribute.

Version:

5.4, December 1, 2009

Author:

Jean-Marie Dautelle

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	XMLFormat.InputElement This class represents an input XML element (unmarshalling).
static class	XMLFormat.OutputElement This class represents an output XML element (marshalling).

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	XMLFormat(java.lang.Class<T> forClass) Defines the default XML format bound to the specified class.

Method Summary

Modifier and Type	Method and Description
java.lang.Class<T>	getBoundClass() Returns the class/interface statically bound to this format or null if none.
static <T> XMLFormat<T>	getInstance(java.lang.Class<? extends T> forClass) Returns the default format for the specified class/interface.
boolean	isReferenceable() Indicates if the object serialized through this format can be referenced to (default true).
T	newInstance(java.lang.Class<T> cls, XMLFormat.InputElement xml) Allocates a new object of the specified class from the specified XML input element.
abstract void	read(XMLFormat.InputElement xml, T obj) Parses an XML input element into the specified object.
java.lang.String	toString() Returns textual information about this format.
abstract void	write(T obj, XMLFormat.OutputElement xml) Formats an object into the specified XML output element.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

XMLFormat

protected XMLFormat(java.lang.Class<T> forClass)

Defines the default XML format bound to the specified class. If the specified class is null then the format is unbound (unbound formats are used by custom binding instances). The static binding is unique and can only be overriden by custom XMLBinding. For example:

    // Overrides default binding for java.util.Collection.
    class MyBinding extends XMLBinding {
        XMLFormat<Collection> collectionXML = new XMLFormat<Collection>(null) { ... }; // Unbound.
        public XMLFormat getFormat(Class cls) {
            if (Collection.isAssignableFrom(cls)) {
                return collectionXML; // Overrides default XML format.
            } else {
                return super.getFormat(cls);
            }
        }
    }

Parameters:

forClass - the root class/interface to associate to this XML format or null if this format is not bound.

Throws:

java.lang.IllegalArgumentException - if a XMLFormat is already bound to the specified class.

Method Detail

getInstance

public static <T> XMLFormat<T> getInstance(java.lang.Class<? extends T> forClass)

Returns the default format for the specified class/interface. If there no direct mapping for the specified class, the mapping for the specified class interfaces is searched, if none is found the mapping for the parents classes is searched, if still none is found the format for java.lang.Object is returned.

A default xml format exists for the following predefined types:

• java.lang.Object
• java.util.Collection
• java.util.Map

The default XML representation (java.lang.Object) consists of the of a "value" attribute holding its textual representation (see TextFormat.getInstance(java.lang.Class<? extends T>)).

Returns:

the class/interface bound to this format.

getBoundClass

public final java.lang.Class<T> getBoundClass()

Returns the class/interface statically bound to this format or null if none.

Returns:

the class/interface bound to this format.

isReferenceable

public boolean isReferenceable()

Indicates if the object serialized through this format can be referenced to (default true). This method can be overriden to return false if serialized objects are manipulated "by value".

Returns:

true if serialized object may hold a reference; false otherwise.

See Also:

XMLReferenceResolver

newInstance

public T newInstance(java.lang.Class<T> cls,
                     XMLFormat.InputElement xml)
              throws XMLStreamException

Allocates a new object of the specified class from the specified XML input element. By default, this method returns an object created using the public no-arg constructor of the specified class. XML formats may override this method in order to use private/multi-arg constructors.

Parameters:

cls - the class of the object to return.

xml - the XML input element.

Returns:

the object corresponding to the specified XML element.

Throws:

XMLStreamException

write

public abstract void write(T obj,
                           XMLFormat.OutputElement xml)
                    throws XMLStreamException

Formats an object into the specified XML output element.

Parameters:

obj - the object to format.

xml - the XMLElement destination.

Throws:

XMLStreamException

read

public abstract void read(XMLFormat.InputElement xml,
                          T obj)
                   throws XMLStreamException

Parses an XML input element into the specified object.

Parameters:

xml - the XML element to parse.

obj - the object created through newInstance(java.lang.Class<T>, javolution.xml.XMLFormat.InputElement) and to setup from the specified XML element.

Throws:

XMLStreamException

toString

public java.lang.String toString()

Returns textual information about this format.

Overrides:

toString in class java.lang.Object

Returns:

this format textual information.