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    copied!<p>Here is a quick DOM example that shows how to read and write a simple xml file with its dtd:</p> <pre><code>&lt;?xml version="1.0" encoding="UTF-8" standalone="no"?&gt; &lt;!DOCTYPE roles SYSTEM "roles.dtd"&gt; &lt;roles&gt; &lt;role1&gt;User&lt;/role1&gt; &lt;role2&gt;Author&lt;/role2&gt; &lt;role3&gt;Admin&lt;/role3&gt; &lt;role4/&gt; &lt;/roles&gt; </code></pre> <p>and the dtd:</p> <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt; &lt;!ELEMENT roles (role1,role2,role3,role4)&gt; &lt;!ELEMENT role1 (#PCDATA)&gt; &lt;!ELEMENT role2 (#PCDATA)&gt; &lt;!ELEMENT role3 (#PCDATA)&gt; &lt;!ELEMENT role4 (#PCDATA)&gt; </code></pre> <p>First import these:</p> <pre><code>import javax.xml.parsers.*; import javax.xml.transform.*; import javax.xml.transform.dom.*; import javax.xml.transform.stream.*; import org.xml.sax.*; import org.w3c.dom.*; </code></pre> <p>Here are a few variables you will need:</p> <pre><code>private String role1 = null; private String role2 = null; private String role3 = null; private String role4 = null; private ArrayList&lt;String&gt; rolev; </code></pre> <p>Here is a reader (String xml is the name of your xml file):</p> <pre><code>public boolean readXML(String xml) { rolev = new ArrayList&lt;String&gt;(); Document dom; // Make an instance of the DocumentBuilderFactory DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); try { // use the factory to take an instance of the document builder DocumentBuilder db = dbf.newDocumentBuilder(); // parse using the builder to get the DOM mapping of the // XML file dom = db.parse(xml); Element doc = dom.getDocumentElement(); role1 = getTextValue(role1, doc, "role1"); if (role1 != null) { if (!role1.isEmpty()) rolev.add(role1); } role2 = getTextValue(role2, doc, "role2"); if (role2 != null) { if (!role2.isEmpty()) rolev.add(role2); } role3 = getTextValue(role3, doc, "role3"); if (role3 != null) { if (!role3.isEmpty()) rolev.add(role3); } role4 = getTextValue(role4, doc, "role4"); if ( role4 != null) { if (!role4.isEmpty()) rolev.add(role4); } return true; } catch (ParserConfigurationException pce) { System.out.println(pce.getMessage()); } catch (SAXException se) { System.out.println(se.getMessage()); } catch (IOException ioe) { System.err.println(ioe.getMessage()); } return false; } </code></pre> <p>And here a writer:</p> <pre><code>public void saveToXML(String xml) { Document dom; Element e = null; // instance of a DocumentBuilderFactory DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); try { // use factory to get an instance of document builder DocumentBuilder db = dbf.newDocumentBuilder(); // create instance of DOM dom = db.newDocument(); // create the root element Element rootEle = dom.createElement("roles"); // create data elements and place them under root e = dom.createElement("role1"); e.appendChild(dom.createTextNode(role1)); rootEle.appendChild(e); e = dom.createElement("role2"); e.appendChild(dom.createTextNode(role2)); rootEle.appendChild(e); e = dom.createElement("role3"); e.appendChild(dom.createTextNode(role3)); rootEle.appendChild(e); e = dom.createElement("role4"); e.appendChild(dom.createTextNode(role4)); rootEle.appendChild(e); dom.appendChild(rootEle); try { Transformer tr = TransformerFactory.newInstance().newTransformer(); tr.setOutputProperty(OutputKeys.INDENT, "yes"); tr.setOutputProperty(OutputKeys.METHOD, "xml"); tr.setOutputProperty(OutputKeys.ENCODING, "UTF-8"); tr.setOutputProperty(OutputKeys.DOCTYPE_SYSTEM, "roles.dtd"); tr.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "4"); // send DOM to file tr.transform(new DOMSource(dom), new StreamResult(new FileOutputStream(xml))); } catch (TransformerException te) { System.out.println(te.getMessage()); } catch (IOException ioe) { System.out.println(ioe.getMessage()); } } catch (ParserConfigurationException pce) { System.out.println("UsersXML: Error trying to instantiate DocumentBuilder " + pce); } } </code></pre> <p>getTextValue is here:</p> <pre><code>private String getTextValue(String def, Element doc, String tag) { String value = def; NodeList nl; nl = doc.getElementsByTagName(tag); if (nl.getLength() &gt; 0 &amp;&amp; nl.item(0).hasChildNodes()) { value = nl.item(0).getFirstChild().getNodeValue(); } return value; } </code></pre> <p>Add a few accessors and mutators and you are done!</p>
 

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