SV: [jdom-interest] Problem running JDOM app using XPath

[Per Norrman]

Hi,

something foes wrong in saxpath library. Try unwrapping the root exception
to
get the message:

try {
   String path = "//resources/dms[()@name='MySQL']/data_source
[@name='Login']/url";
   .....
} catch (JDOMException e) {
   Throwable t = e.getCause();
   if (t != null) {
      System.out.println(t.getMessage());
      if (t instanceof JaxenException) {
         Throwable tt = ((JaxenException)t).getRootCause();
         System.out.println(tt);
      }
   }
} catch (IOException e) {
   e.printStackTrace();
}

-----Ursprungligt meddelande-----
Från: jdom-interest-admin at jdom.org [mailto:jdom-interest-admin at jdom.org] För
AH
Skickat: den 21 juni 2003 21:01
Till: JDOM Interest
Ämne: [jdom-interest] Problem running JDOM app using XPath


Hello everybody...I am using JDOM's XPath facility for the first time and
have followed all the rules on written proper XPath expressions...I have
also followed the rules in the program logic to set up XPath using JDOM but
there seems to be a major problem...Not just with my program but I get
pretty much the same error message when I try to run the sample programs
that come with Jaxen for the JDOM API...I don't know were I am going wrong
here...please help...I have provided a short program and xml file for
testing purposes...could it be that I need to install something else...I
have the latest version of Jaxen and JDOM installed...My JDOM and Jaxen APIs
are recognized by the JVM...don't understand it...thanks in advance for any
help...


Java source

import org.jdom.Document;
import org.jdom.Element;
import org.jdom.JDOMException;
import org.jdom.input.SAXBuilder;
import java.io.File;
import org.jdom.xpath.XPath;


public class TestXPath
{
 public static void main(String [] args) throws Exception
 {
  String path =
"resources/dms[@name='MySQL']/data_source[@name='Login']/url";

  SAXBuilder sax_obj = new SAXBuilder();
  Document doc = sax_obj.build(new File("config.xml"));
  XPath xpath = XPath.newInstance(path);
  Element node = (Element)XPath.selectSingleNode(doc.getRootElement(),
path);

  System.out.println("URL:\t" + node.getTextNormalize());
 }
}



XML source

<?xml version="1.0" encoding="UTF-8"?>
<resources>
 <dms name="MySQL" driver="com.mysql.jdbc.Driver">
  <data_source name="Login" type="database">
   <url>jdbc:mysql://localhost/login</url>
  </data_source>
  <data_source name="Authentication" type="database">
   <url>jdbc:mysql://localhost/authentication</url>
  </data_source>
  <data_source name="Key" type="database">
   <url>jdbc:mysql://localhost/user_key</url>
  </data_source>
  <data_source name="ID" type="database">
   <url>jdbc:mysql://localhost/id</url>
  </data_source>
 </dms>
</resources>

I get the following error message when the above program is ran against the
above xml file...

Exception in thread "main" org.jdom.JDOMException: Invalid XPath expression:
"resources/dms[@name='MySQL']/data_source[@
name='Login']/url": wrapped exception
        at org.jdom.xpath.JaxenXPath.setXPath(JaxenXPath.java:288)
        at org.jdom.xpath.JaxenXPath.<init>(JaxenXPath.java:101)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native
Method)
        at
sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAcces
sorImpl.java:39)
        at
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstruc
torAccessorImpl.java:27)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:274)
        at org.jdom.xpath.XPath.newInstance(XPath.java:136)
        at TestXPath.main(TestXPath.java:17)
Caused by: org.jaxen.JaxenException: wrapped exception
        at org.jaxen.BaseXPath.<init>(BaseXPath.java:142)
        at org.jaxen.BaseXPath.<init>(BaseXPath.java:157)
        at org.jaxen.jdom.JDOMXPath.<init>(JDOMXPath.java:103)
        at org.jdom.xpath.JaxenXPath.setXPath(JaxenXPath.java:284)
        ... 7 more
Caused by: org.jaxen.JaxenException: wrapped exception
        at org.jaxen.BaseXPath.<init>(BaseXPath.java:142)
        at org.jaxen.BaseXPath.<init>(BaseXPath.java:157)
        at org.jaxen.jdom.JDOMXPath.<init>(JDOMXPath.java:103)
        at org.jdom.xpath.JaxenXPath.setXPath(JaxenXPath.java:284)
        at org.jdom.xpath.JaxenXPath.<init>(JaxenXPath.java:101)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native
Method)
        at
sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAcces
sorImpl.java:39)
        at
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstruc
torAccessorImpl.java:27)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:274)
        at org.jdom.xpath.XPath.newInstance(XPath.java:136)
        at TestXPath.main(TestXPath.java:17)
Caused by: org.jaxen.JaxenException: wrapped exception
        at org.jaxen.BaseXPath.<init>(BaseXPath.java:142)
        at org.jaxen.BaseXPath.<init>(BaseXPath.java:157)
        at org.jaxen.jdom.JDOMXPath.<init>(JDOMXPath.java:103)
        at org.jdom.xpath.JaxenXPath.setXPath(JaxenXPath.java:284)
        at org.jdom.xpath.JaxenXPath.<init>(JaxenXPath.java:101)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native
Method)
        at
sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAcces
sorImpl.java:39)
        at
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstruc
torAccessorImpl.java:27)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:274)
        at org.jdom.xpath.XPath.newInstance(XPath.java:136)
        at TestXPath.main(TestXPath.java:17)
Press any key to continue . . .


Can anybody help...I am thinking that there is a problem with Jaxen but dont
know enough about the API to figure out what...please help...


AH