Re: URLClassLoader problems

[John Gentilin]

I use the URLClassloader with out problem, unless Tomcat was started 
with the -security option, then I get
security failures. I have been using 4.1.30 and earlier. Could it be a 
relative directory thing, have you tried to
open the jar in your constructor to make sure you have access to the file ??

HTH
John  G
Chris Picton wrote:
Hi
I am trying to use the following code to load a class from a jar file
which is outside of my webapp directory.  The classes are loaded on
demand and dynamically.
...
public class JarClassLoader extends URLClassLoader {
  public JarClassLoader(File jar) throws MalformedURLException {
     super(new URL[] { jar.toURL() });
  }
        
  public Object instantiate(String className) throws
ClassNotFoundException, InstantiationException, IllegalAccessException {
     System.out.println("Looking for class: " + className);
     Class c = findClass(className);
     return c.newInstance();
  }
}
...
JarClassLoader loader = new JarClassLoader(new File(jarPath));
Object o = loader.instantiate(myClassName);
...
If I run the code from an app, it loads without any problems.  If I use
it within a tomcat Servlet, the 'instantiate' call throws a
java.lang.NoClassDefFoundError.
I have checked that the tomcat user can access the jar file, so it does
not seem to be a permission problem.
Does the tomcat container limit access to classes outside of its
classpath?  Is there something simple I am missing?
Regards
Chris
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