Simple xml config file

Question

I have created a simple config file using something like:
      XMLEncoder e = new XMLEncoder(
                                  new BufferedOutputStream(
                                      new FileOutputStream("Config.xml")));
      e.writeObject(base.toString());
      e.writeObject(numberFrom);
      e.writeObject(numberTo);
      e.writeObject(numberPad);
      e.writeObject(maxTasks);
      e.writeObject(maxSubTasks);
      e.writeObject(textFrom);
      e.writeObject(textTo);
      e.close();which produces a file like:
<?xml version="1.0" encoding="UTF-8"?>
<java version="1.4.2_05" class="java.beans.XMLDecoder">
<string>C:\</string>
<int>1</int>
<int>20</int>
<int>2</int>
<int>0</int>
<int>1</int>
<string>a</string>
<string>z</string>
</java> I want to make it a bit more version proof so need to get something more like:
<?xml version="1.0" encoding="UTF-8"?>
<program name=myprog>
<dir>C:\</dir>
<version>1</version>
<myval1>20</myval1>
<myval2>2</myval2>
</program>There's probably loads of errors in that bit;) but you get the idea. I'm a bit new to xml programming.
Can anyone give me any urls of help or examples that might do this?
Thanks,
David.

Answer 1

You could use a binding api such as JAXB or xmlbeans. In essence these apis abstract the xml as pure java objects. Alternatively you could use an xml parser such as dom4j and build the XML 'by hand'. This class will create an example config file and write it to the file system
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import org.apache.xml.serialize.OutputFormat;
import org.apache.xml.serialize.XMLSerializer;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Text;
* Class to create a simple xml config file using W3C api
* @author wollnyj
public class CreateConfig {
     * create the config file
     *?xml version="1.0" encoding="UTF-8"?>
     *<program name=myprog>
     *    <dir>C:\</dir>
     *    <version>1</version>
     *    <myval1>20</myval1>
     *    <myval2>2</myval2>
     *</program>
     * @param configFile
     * @throws ParserConfigurationException
     * @throws IOException
    public CreateConfig(String configFile) throws ParserConfigurationException, IOException {
        //Document doc = parseXml(configFile);
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        Document doc = factory.newDocumentBuilder().newDocument();
        Element program = doc.createElement("program");
        program.setAttribute("name","myprog");
        Element dir = createEle("dir","c:\\",doc);
        Element version = createEle("version","1",doc);
        Element val1 = createEle("myval1","20",doc);
        // etc...
        program.appendChild(dir);
        program.appendChild(version);
        program.appendChild(val1);
        doc.appendChild(program);
        write(doc,new File(configFile));
     * @param args
     * @throws Exception
    public static void main(String[]args) throws Exception {
        CreateConfig create = new CreateConfig("F:\\config.xml");
     * Write an xml document to the file system
     * @param document The document to be written
     * @param xmlFile The output file
     * @throws IOException The file does not exist or could not be created
    private void write(Document document, File xmlFile) throws IOException {
        OutputFormat format = new OutputFormat(document);
        format.setIndent(4);
        format.setLineSeparator(System.getProperty("line.separator"));
        format.setLineWidth(80);
        FileWriter writer = new FileWriter(xmlFile);
        XMLSerializer fileSerial = new XMLSerializer(new BufferedWriter(writer), format);
        fileSerial.asDOMSerializer();
        fileSerial.serialize(document);
    private Element createEle(String name, String value, Document doc) {
        Element ele = doc.createElement(name);
        Text textNode = doc.createTextNode(value);
        ele.appendChild(textNode);
        return ele;
}