Java by API/java.net/URLClassLoader

extends URLClassLoader

  

import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.net.JarURLConnection;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.jar.Attributes;
public class Main extends URLClassLoader {
  private URL url;
  public Main(URL url) {
    super(new URL[] { url });
    this.url = url;
  }
  public String getMainClassName() throws IOException {
    URL u = new URL("jar", "", url + "!/");
    JarURLConnection uc = (JarURLConnection) u.openConnection();
    Attributes attr = uc.getMainAttributes();
    return attr != null ? attr.getValue(Attributes.Name.MAIN_CLASS) : null;
  }
  public void invokeClass(String name, String[] args) throws ClassNotFoundException,
      NoSuchMethodException, InvocationTargetException {
    Class c = loadClass(name);
    Method m = c.getMethod("main", new Class[] { args.getClass() });
    m.setAccessible(true);
    int mods = m.getModifiers();
    if (m.getReturnType() != void.class || !Modifier.isStatic(mods) || !Modifier.isPublic(mods)) {
      throw new NoSuchMethodException("main");
    }
    try {
      m.invoke(null, new Object[] { args });
    } catch (IllegalAccessException e) {
    }
  }
}

new URLClassLoader(URL[] urls)

  
import java.lang.reflect.Method;
import java.net.URL;
import java.net.URLClassLoader;
public class Main {
  static public void main(String args[]) throws Exception {
    URL myurl[] = { new URL("file:///C:/CH3/ClassLoader/web/"),
        new URL("http://www.jexp.edu/~xyx/test/") };
    URLClassLoader x = new URLClassLoader(myurl);
    Class c = x.loadClass("TestURL");
    Class getArg1[] = { (new String[1]).getClass() };
    Method m = c.getMethod("main", getArg1);
    String[] my1 = { "arg1 passed", "arg2 passed" };
    Object myarg1[] = { my1 };
    m.invoke(null, myarg1);
    Object ob = c.newInstance();
    Class arg2[] = {};
    Method m2 = c.getMethod("tt", arg2);
    m2.invoke(ob, null);
    Class arg3[] = { (new String()).getClass(), int.class };
    Method m3 = c.getMethod("tt", arg3);
    Object myarg2[] = { "Arg1", new Integer(100) };
    m3.invoke(ob, myarg2);
  }
}

URLClassLoader: getURLs()

  
import java.net.URL;
import java.net.URLClassLoader;
public class Main {
  public static void main(String[] args) {
    ClassLoader sysClassLoader = ClassLoader.getSystemClassLoader();
    URL[] urls = ((URLClassLoader) sysClassLoader).getURLs();
    for (int i = 0; i < urls.length; i++) {
      System.out.println(urls[i].getFile());
    }
  }
}