XOM教程

XOM Tutorial
                                 Elliotte Rusty Harold

     Copyright © 2002-2008 Elliotte Rusty Harold

Table of Contents

Creating XML Documents

Appending children
Serializer
Attributes
Document Type Declarations
Namespaces

Parsing XML Documents

Validating
Setting SAX Properties

Navigation

Element Navigation
Siblings
Attributes

The Node Superclass
The ParentNode Class
Factories, Filters, Subclassing, and Streaming
XPath
XSLT

Custom Node Factories

Canonicalization
XInclude
Summary

 

 XOM is designed to be easy to learn and easy to use.  It works very straight-forwardly, and has a very shallow learning curve.  Assuming you're already familiar with XML, you should be  able to get up and running with XOM very quickly.
  Creating XML Documents

  Let’s begin, as customary, with a Hello World program.  In particular, suppose we want to create this XML document:

  

<?xml version="1.0"?>
<root>
  Hello World!
</root>

 

First we have to import the nu.xom package where most of the interesting classes live:

import nu.xom.*;

This document contains a single element, named root, so we create an Element object named “root”:

Element root = new Element("root");

Next we append the string "Hello World!" to it:

 

root.appendChild("Hello World!");

Now that we have the root element, we can use it to create the   Document object:

Document doc = new Document(root);

We can create a String containing the  XML for this Document object using  its toXML method:

String result = doc.toXML();

This string can be written onto  an OutputStream or a  Writer  in the usual way. Here’s the complete program:

Example 1. Hello World with XOM

import nu.xom.*;

public class HelloWorld {

  public static void main(String[] args) {
   
    Element root = new Element("root");    
    root.appendChild("Hello World!");
    Document doc = new Document(root);
    String result = doc.toXML();
    System.out.println(result);
    
  }
 
}

 

  This is compiled and run in the usual way. When that’s done, here’s the output:

 

<?xml version="1.0"?>
<root>Hello World!</root>

 

You may notice that this isn't quite what the goal was.
The white space is different. On reflection, this shouldn't be too surprising.
White space is significant in XML. If you want line breaks and indentation,
you should include that in the strings you use to construct the
data. For example,

root.appendChild("\n  Hello World!\n");