Importare file jar

[prog]

Allora si la classe che mi hai detto fa proprio al mio caso in rete però ho trovato la seguete classe che dovrebbe importare un jar a runtime

package classloader;  
import java.io.*; 
import java.net.*; 
import java.util.jar.*;   
public class MyJarLoader {    
   public static void main(String[] args) throws FileNotFoundException, IOException {    
       String jarName = "/home/joaquin/Scrivania/Tirocinio/jfreechart-1.0.9/lib/servlet.jar"; 
       URLClassLoader urlLoader = getURLClassLoader(new URL("file", null, jarName));      
        JarInputStream jis = new JarInputStream(new FileInputStream(jarName));     
        JarEntry entry = jis.getNextJarEntry();     int loadedCount = 0, totalCount = 0;      
        while (entry != null) {       
             String name = entry.getName();      
             if (name.endsWith(".class")) {         
                                 totalCount++;        
                                 name = name.substring(0, name.length() - 6);        
                                 name = name.replace('/', '.');         
                                 System.out.print("> " + name);           
                                 try {           
                                        urlLoader.loadClass(name);           
                                        System.out.println("\t- loaded");           
                                        loadedCount++;         
                                      } 
                                 catch (Throwable e) {           
                                     System.out.println("\t- not loaded");           
                                     System.out.println("\t " + e.getClass().getName() +":"e.getMessage());        
                                 }         
             }       
           entry = jis.getNextJarEntry();     
         }       
        System.out.println("\n---------------------");     
        System.out.println("Summary:");      
        System.out.println("\tLoaded:\t" + loadedCount);      
        System.out.println("\tFailed:\t" + (totalCount - loadedCount));      
        System.out.println("\tTotal:\t" + totalCount);           
        try {         
             Object o=Class.forName("javax.servlet.FilterConfig").newInstance();     
         } catch (InstantiationException e) {         
               // TODO Auto-generated catch block         
          e.printStackTrace();     } 
         catch (IllegalAccessException e) {         
              // TODO Auto-generated catch block         
               e.printStackTrace();     } 
          catch (ClassNotFoundException e) {         
             // TODO Auto-generated catch block         
             e.printStackTrace();     }   
          }      
      private static URLClassLoader getURLClassLoader(URL jarURL) {     
          return new URLClassLoader(new URL[]{jarURL});   
      } 
    } 

ma in pratica quando creo un'istanza della classe mi dice ClassNotFoundException.