reading web.xml by XPATH

[S Shehab]

Hi Guys ,

i'm new to XPATH , i'm trying to read a copy of the web.xml named testweb.xml , but i didnt get any results , only the program prints "for done " and nothing else , here is my code

  DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory .newInstance();
			documentBuilderFactory.setNamespaceAware(true);
		DocumentBuilder builder = documentBuilderFactory.newDocumentBuilder();
			Document doc = builder.parse("testweb.xml");

		XPathFactory xPathFactory = XPathFactory.newInstance();
			XPath xpath = xPathFactory.newXPath();

			XPathExpression expr = xpath.compile("/wep-app/context-param/param-name");// "wep-app/context-param//param-name"
			Object results = expr.evaluate(doc, XPathConstants.NODESET);
			NodeList nodes1stName = (NodeList) results;

		    for (int i = 0; i < nodes1stName.getLength(); i++)
			{
				System.out.println(nodes1stName.item(i).getTextContent());

	}
			System.out.println("for done");//the program  prints this only !!

		}

		catch (XPathExpressionException e)
		{
			e.printStackTrace();
		}
		catch (ParserConfigurationException e)
		{
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		catch (SAXException e)
		{
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		catch (IOException e)
		{
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		catch (Exception e)
		{
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}  

anything i;m missing ?

[Vinod Tiwari]

Hi Sherif,

Please correct your subject. I think you wanted to write web.xml.

Further below XPathExpression does not seems to be right..

XPathExpression expr = xpath.compile("/wep-app/context-param/param-name");

Please go through this for clarity on XPATH.

[S Shehab]

Vinod Tiwari wrote:Hi Sherif,

Please correct your subject. I think you wanted to write web.xml.

Further below XPathExpression does not seems to be right..

XPathExpression expr = xpath.compile("/wep-app/context-param/param-name");

Please go through this for clarity on XPATH.

Hi , i cant find anything wrong ...

[Paul Clapham]

All that means is that the XPath expression you chose doesn't select any nodes from the document. One would have to look at the document to see why not. And right now, you're the only one who can do that. We can't see it from here.

[S Shehab]

Paul Clapham wrote:All that means is that the XPath expression you chose doesn't select any nodes from the document. One would have to look at the document to see why not. And right now, you're the only one who can do that. We can't see it from here.

Sorry You are right Paul , i forget to post the web.xml file , here is the part that i wanna get from the xml file

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5">
  <display-name>web xml test</display-name>
  <context-param>
    <param-name>testingDBUrl</param-name>
    <param-value>value1</param-value>
  </context-param>
  <context-param>
    <param-name>testingDBUser</param-name>
    <param-value>user</param-value>
  </context-param>
  <context-param>
    <param-name>testingDbPass</param-name>
    <param-value>password</param-value>
  </context-param>
  <context-param>
    <description></description>
    <param-name>testingDbDriver</param-name>
    <param-value>oracle.jdbc.driver.OracleDriver</param-value>
  </context-param>
  <context-param>
    <description></description>
    <param-name>DB_Secondary_Url</param-name>
    <param-value>value2</param-value>
  </context-param>

</web-app>

    

[Paul Clapham]

Clearly your first error is that the XPath expression is looking for a "wep-app" element as the root, whereas the root of that document is a "web-app" element.

But you're going to come back and tell me that was just a typing error when you made the post, the actual code does say "web-app". Then your problem is that all of your document is in the default namespace, whereas an XPath expression specifying an element name with no prefix is looking for elements with no namespace.

You can fix that by creating a namespace context which assigns the prefix "x" to the namespace URI "http://java.sun.com/xml/ns/javaee", and assigning that namespace context to your XPath object. Then change the XPath expression to "/x:web-app/x:context-param/x:param-name".

[S Shehab]

Yhanks for your fast reply , do you mean putting this

 xmlns:x="http://java.sun.com/xml/ns/javaee"
   

and it will be like this

 <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee"  xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5"   xmlns:x="http://java.sun.com/xml/ns/javaee">   

then the XPATh expression object will be like this

 XPathExpression expr = xpath.compile("/x:web-app /x:context-param/x:param-name" );  

Am i right ?

[Paul Clapham]

No.

If I was going to suggest changing the XML document, I would have suggested just getting rid of the default namespace declaration. But I didn't suggest changing the XML document at all, because for all I know changing it would break something. What gave you that idea?

[Vinod Tiwari]

Your xpath should be something like

 /web-app/context-param[i]/param-name/

where i=1,2,...