Xerces Serialization

The Apache XML Project's Xerces-J includes the org.apache.xml.serialize package for writing DOM Document objects onto output streams. Although this class is bundled with Xerces, it works with any DOM2 implementation. It does not depend on the details of the Xerces implementation classes, only on the standard DOM interfaces.

The basic technique for serializing documents with org.apache.xml.serialize is as follows :

1. Configure an OutputFormat object with the serialization options you want.

2. Connect an OutputStream to the location where you want to store the data.

3. Use the OutputStream and the OutputFormat to construct a new XMLSerializer object.

4. Pass the Document object you want to serialize to the XMLSerializer 's serialize() method.

For example, the following code could replace the JAXP ID transform from several examples in the last few chapters:

 try {   OutputFormat format = new OutputFormat(document);   XMLSerializer output = new XMLSerializer(System.out, format);   output.serialize(document); } catch (IOException e) {   System.err.println(e); } 

XMLSerializer has a number of advantages over JAXP, including maintaining the document type declaration. Furthermore, it's much more configurable.

XMLSerializer has several constructors. Which to choose depends on whether you want to write to an OutputStream or a Writer , and whether or not you want to provide an OutputFormat when you create the serializer:

 public  XMLSerializer  ()  public  XMLSerializer  (OutputFormat  format  ) public  XMLSerializer  (Writer  out,  OutputFormat  format  ) public  XMLSerializer  (OutputStream  out,  OutputFormat  format  ) 

Generally I recommend that you specify both the format and the stream or writer when you construct the XMLSerializer . That said, you can set them or change them later with these methods :

 public void  setOutputFormat  (OutputFormat  format  )  public void  setOutputByteStream  (OutputStream  out  ) public void  setOutputCharStream  (Writer  out  ) 

You must specify either the byte stream or the char stream before you can serialize.

If you don't want to serialize the entire document, then you can pass just an Element or a DocumentFragment to the serialize() method:

 public void  serialize  (DocumentFragment  fragment  )  throws IOException public void  serialize  (Document  doc  ) throws IOException public void  serialize  (Element  element  ) throws IOException 

There are many other methods in the XMLSerializer class that, for the most part, you should ignore, unless you're subclassing it.