My XML file:
<?xml version="1.0" encoding="UTF-8"?>
<devices>
<device mobile="true" supported="false">Windows CE</device>
<device mobile="false" minVersion="2">Firefox</device>
<device mobile="false" minVersion="3">Safari</device>
<device mobile="false" minVersion="6">MSIE</device>
<device mobile="false" minVersion="1">Chrome</device>
</devices>
From Java, if we give input as "Firefox", the output should be mobile=false and minversion=2.
How can I get this data from the XML using Java?
You can use JAXB. First you need to get the XSD (or even DTD) from the creator of the xml. Then you can use a tool like xjc from Java to create your classes (and/or source code) for unpacking the XML string/file into Java objects.
Once you've done that, you can use the Java JAXB classes to build Java objects from the XML. For a simple example:
(MyObject)JAXBContext.newInstance("package.where.xjc.generated.the.classes")
.createUnmarshaller()
.unmarshal(readerOrStreamOrFileOrURL);
Check out this for more information.
http://java.sun.com/developer/codesamples/xml.html#dom
Check out the examples.
An easy way is using dom4j, that I think it is simpler than SAX: http://dom4j.sourceforge.net/ , but needs more memory.
Generally, it's always connected with parsing XML. Try this: http://www.ibm.com/developerworks/library/x-javaxpathapi.html
Using XPathFactory you could do:
import java.util.*;
import java.lang.*;
import javax.xml.parsers.*;
import org.w3c.dom.*;
import javax.xml.xpath.*;
class Main
{
public static void main (String[] args) throws java.lang.Exception
{
DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance();
domFactory.setNamespaceAware(true);
DocumentBuilder builder = domFactory.newDocumentBuilder();
Document doc = builder.parse("Devices.xml");
XPathFactory factory = XPathFactory.newInstance();
XPath xpath = factory.newXPath();
XPathExpression expr = xpath.compile("//devices/device[@mobile='false' and @minVersion='2']/text()");
Object result = expr.evaluate(doc, XPathConstants.NODESET);
NodeList nodes = (NodeList) result;
for (int i = 0; i < nodes.getLength(); i++) {
System.out.println(nodes.item(i).getNodeValue());
}
}
}
The output:
Firefox
You'll need to use an XML parser. I recommend XOM. It makes parsing XML files a breeze. They have good documentation on how to accomplish this as well.
An example:
Document doc = new XmlBuilder().build(new File("path/to/file"));
Element devicesElement = doc.getRootElement();
Elements deviceElements = devicesElement.getChildElements();
for (int i = 0; i < deviceElements.size(); i++) {
Element curDevice = deviceElements.get(i);
....
}
