JDom working with XPath

问题

I am a newbie to JDom, I try to use XPath to access my xml file. My code is like following:

public static void main(String[] args) throws Exception {
    Document doc = new SAXBuilder().build("file.xml");
    XPath x = XPath.newInstance("xpath");

    //select the first element in the nodeset
    Element elem = (Element)x.selectSingleNode(doc);
    ......
}

I have already imported org.jdom.xpath.XPath class. When I use javac to compile the class, it didn't give any error, however when I try to run the program, it gives the following exception message:

Exception in thread "main" java.lang.NoClassDefFoundError: org/jaxen/NamespaceContext
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Class.java:169)
        at org.jdom.xpath.XPath.newInstance(XPath.java:134)
        at myclassname.main(xmlTohtml.java:18)
Caused by: java.lang.ClassNotFoundException: org.jaxen.NamespaceContext
        at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:276)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
        at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)
        ... 4 more

Did I miss something here? Any help will be greatly appreciated!

I add the jaxen and dom4j in my .cshrc file which resides directly under my home directory, and the two jar files are in the same directory too.

setenv CLASSPATH ${CLASSPATH}:/homedirectory/jaxen-1.1.1.jar
setenv CLASSPATH ${CLASSPATH}:/homedirectory/dom4j-1.6.1.jar

When I try this command from the command line, it generates new exceptions....

Exception in thread "main" java.lang.NoClassDefFoundError: :
Caused by: java.lang.ClassNotFoundException: :
    at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:276)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
    at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)

By the way, the imported classes in my program are:

import java.util.Iterator;
import org.jdom.Document;
import org.jdom.Element;
import org.jdom.input.SAXBuilder;
import org.jdom.Namespace;
import org.jdom.xpath.XPath;

回答1:

Include dom4j.jar and jaxen.jar in classpath.

回答2:

I suspect you don't have jaxen-1.1.3.jar on the classpath. If I were to assume you were running this from the command line, you'd want:

java -cp jaxen-1.1.3.jar:. myJavaProgram

回答3:

Just jaxen1.1.3 is sufficient and dom4j not required

来源：https://stackoverflow.com/questions/7058158/jdom-working-with-xpath

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sax

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