XPath and Name Spaces, don't you hate them too??

How about running a XPath expression from Java?
Pretty straight forward right, oh wait NAMESPACE!!!!

Here's a example on how to create your xpaht parser and the more complex Name Space Context.
Let's start with the NameSpaceContextImpl

	import java.util.HashMap;
	import java.util.Iterator;
	import java.util.Map;
	import javax.xml.XMLConstants;
	import javax.xml.namespace.NamespaceContext;
	import org.apache.commons.lang.Validate;
	public class NamespaceContextImpl implements NamespaceContext {
	private Map<String, String> namespaceMap = new HashMap<String, String>();
	public NamespaceContextImpl(Map<String, String> namespaceMap) {
	this.namespaceMap = namespaceMap;
	}
	public void addNamespace(String prefix, String uri) {
	Validate.notEmpty(prefix, "The prefix can not be null nor empty");
	Validate.notEmpty(uri, "The uri can not be null nor empty");
	this.namespaceMap.put(prefix, uri);
	}
	public String getNamespaceURI(String prefix) {
	String uri = this.namespaceMap.get(prefix);
	return uri == null ? XMLConstants.NULL_NS_URI : uri;
	}
	public String getPrefix(String namespace) {
	for (String prefix : this.namespaceMap.keySet()) {
	if (this.namespaceMap.get(prefix).equals(namespace)) {
	return prefix;
	}
	}
	return null;
	}
	public Iterator getPrefixes(String namespace) {
	return null;
	}
	}

view raw NamespaceContextImpl.java hosted with ❤ by GitHub

Now the actual Xpath parser imple:

	DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
	factory.setNamespaceAware(true); // never forget this!
	DocumentBuilder builder = factory.newDocumentBuilder();
	Document doc = builder.parse(new ByteArrayInputStream(xml.getBytes()));
	// here's the fun part define your name spaces
	Map<String, String> namesapaceMap = new HashMap<String, String>();
	namesapaceMap.put("xmlns", "http://your.name.space.location.com/something/something");
	// feed your context with the namespaces
	NamespaceContext context = new NamespaceContextImpl(namesapaceMap);
	XPath xpath = XPathFactory.newInstance().newXPath();
	xpath.setNamespaceContext(context);
	// run your xpath
	System.out.println(xpath.compile("//Fields").evaluate(doc));

view raw gistfile1.java hosted with ❤ by GitHub

Hope it helps guy!!!

The famous Jar Hell issue

So I reckon I'm not the first one to have this problem. I'm certainly not the one who will tell you how to solve it BUT!!!!

Here is a really small example about using the JHades tool 

Why am I posting this?
Because the example in the home page is a little bit outdated and if you search JHades for the maven dependency the first 4 links you hit get it wrong.


Maven Dependency

	<dependency>
	<groupId>org.jhades</groupId>
	<artifactId>jhades</artifactId>
	<version>1.0.4</version>
	</dependency>

view raw gistfile1 hosted with ❤ by GitHub

Java Code

	import org.jhades.JHades;
	new JHades()
	.printClassLoaderNamess()
	.printClasspath()
	.overlappingJarsReport()
	.multipleClassVersionsReport()
	.findClassByName("org.jhades.SomeServiceImpl")

view raw gistfile1.java hosted with ❤ by GitHub

You should place this in some place that you are sure it'll get run during building.
If you have issues during tests. Just create a test where the test method has this code.

Hope this helps!