I have a method (getSingleNodeValue()) which when passed an xpatch expression will extract the value of the specified element in the xml document refered to in ‘doc’. Assume doc at this point has been initialised as shown below and xmlInput is the buffer containing the xml content.
SAXBuilder builder = null;
Document doc = null;
XPath xpathInstance = null;
doc = builder.build(new StringReader(xmlInput));
When i call the method, i pass the following xpath xpression
/TOP4A/PERLODSUMDEC/TINPLD1/text()
Here is the method. It basically just takes an xml buffer and uses xpath to extract the value:
public static String getSingleNodeValue(String xpathExpr) throws Exception{
Text list = null;
try {
xpathInstance = XPath.newInstance(xpathExpr);
list = (Text) xpathInstance.selectSingleNode(doc);
} catch (JDOMException e) {
throw new Exception(e);
}catch (Exception e){
throw new Exception(e);
}
return list==null ? "?" : list.getText();
}
The above method always returns “?” i.e. nothing is found so ‘list’ is null.
The xml document it looks at is
<TOP4A xmlns="http://www.testurl.co.uk/enment/gqr/3232/1">
<HEAD>
<Doc>ABCDUK1234</Doc>
</HEAD>
<PERLODSUMDEC>
<TINPLD1>10109000000000000</TINPLD1>
</PERLODSUMDEC>
</TOP4A>
The same method works with other xml documents so i am not sure what is special about this one. There is no exception so the xml is valid xml. Its just that the method always sets ‘list’ to null. Any ideas?
Edit
Ok as suggested, here is a simple running program that demonstrates the above
import org.jdom.*;
import org.jdom.input.*;
import org.jdom.xpath.*;
import java.io.IOException;
import java.io.StringReader;
public class XpathTest {
public static String getSingleNodeValue(String xpathExpr, String xmlInput) throws Exception{
Text list = null;
SAXBuilder builder = null;
Document doc = null;
XPath xpathInstance = null;
try {
builder = new SAXBuilder();
doc = builder.build(new StringReader(xmlInput));
xpathInstance = XPath.newInstance(xpathExpr);
list = (Text) xpathInstance.selectSingleNode(doc);
} catch (JDOMException e) {
throw new Exception(e);
}catch (Exception e){
throw new Exception(e);
}
return list==null ? "Nothing Found" : list.getText();
}
public static void main(String[] args){
String xmlInput1 = "<TOP4A xmlns=\"http://www.testurl.co.uk/enment/gqr/3232/1\"><HEAD><Doc>ABCDUK1234</Doc></HEAD><PERLODSUMDEC><TINPLD1>10109000000000000</TINPLD1></PERLODSUMDEC></TOP4A>";
String xpathExpr = "/TOP4A/PERLODSUMDEC/TINPLD1/text()";
XpathTest xp = new XpathTest();
try {
System.out.println(xp.getSingleNodeValue(xpathExpr, xmlInput1));
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
When i run the above, the output is
Nothing found
Edit
I have run some further testing and it appears that if i remove the namespace url it does work. Not sure why yet. Is there any way i can tell it to ignore the namespace?
Edit
Please also note that the above is implemented on JDK1.4.1 so i dont have the options for later version of the JDKs. This is the reason why i had to stick with Jdom.
The problem is with XML namespaces: your XPath query starts by selecting a ‘TOP4A’ element in the default namespace. Your XML file, however, has a ‘TOP4A’ element in the ‘http://www.testurl.co.uk/enment/gqr/3232/1’ namespace instead.
Is it an option to remove the xmlns from the XML?