Learning Java, 4th Edition

XInclude

XInclude is a very simple “import” facility for XML documents. With the XInclude directive, you can easily include one XML document in another either as XML or as plain (and escaped) text. This means that you can break down your documents into as many files as you see fit and reference the pieces in a simple, standard way. We should note that it is also possible to do this in another way, using XML entity declarations, but they are fraught with problems. XInclude is simpler and does what its name implies, including the specified document at the current location; you just have to declare the proper namespace for the new <include> element. Here is an example:

        <Book xmlns:xi="http://www.w3.org/2001/XInclude">
          <Title>Learning Java</Title>
          <xi:include href="chapter1.xml"/>
          <xi:include href="chapter2.xml"/>
          <xi:include href="chapter3.xml"/>
          ...
        </Book>

We’ve used the namespace identifier xi to qualify the <include> elements that we use to import the chapters of our book. By default, the file is imported as XML content, which means that the parser incorporates the included document as part of our document. The resulting DOM or SAX view will show the merged documents as one. Alternatively, we can use the parse attribute to specify that we want the target included as text only. In this case, the text is automatically escaped for us like a CDATA section. For example, we could use it to include an XML example in our book without danger of it being intepreted as part of our file: