Creating and Modifying XML Documents - Beginning Java 2 SDK - page 1076

xmlDoc.append(getDocumentNode(doc.getDocumentElement(), ""));
This is for good reason. We will need a recursive method to navigate the nodes in the Document object
that represent the body of the document and create the XML for that. The string that is returned will be
the entire document body, so once we have appended this to xmlDoc we have the complete document.
We will implement the getDocumentNode() method shortly.
The other statement deserving some explanation is the one in the try block that writes the complete
document to the file:
channel.write(ByteBuffer.wrap(xmlDoc.toString().getBytes("UTF-8")));
Starting from the inside, and working outwards: Calling the toString() method for xmlDoc returns
the contents as type String . We then call the getBytes() method for the String object to obtain
an array of type byte[] containing the contents of the String object encoded as UTF-8. We then call
the static wrap() method in the ByteBuffer class (that will need importing) to create a ByteBuffer
object that wraps the array. The buffer that is returned has its limit and position set ready for the buffer
contents to be written to a file. We can therefore pass this ByteBuffer object directly to the write()
method for the FileChannel object to write the contents of the buffer, which will be the entire XML
document, to the file. How's that for a powerful statement.
The code for the getDoctypeString() method will be:
private String getDoctypeString(org.w3c.dom.DocumentType doctype) {
// Create the opening string for the DOCTYPE declaration with its name
String str = doctype.getName();
StringBuffer doctypeStr = new StringBuffer("<!DOCTYPE ").append(str);
// Check for a system ID
if((str = doctype.getSystemId()) != null)
doctypeStr.append(" SYSTEM ").append(QUOTE).append(str).append(QUOTE);
// Check for a public ID
if((str = doctype.getPublicId()) != null)
doctypeStr.append(" PUBLIC ").append(QUOTE).append(str).append(QUOTE);
// Check for an internal subset
if((str = doctype.getInternalSubset()) != null)
doctypeStr.append('[').append(str).append(']');
return doctypeStr.append(TAG _ END).toString(); // Append '>' & return string
}
This is almost identical to the method as implemented in our previous example.