URLClassLoader and reloading a class from the web example

Reload jar from remote example

import java.lang.reflect.Method;

import java.net.URL;

import java.net.URLClassLoader;

public class UrlJarReloader {

public static void main(String[] args) {

Runnable r = new Runnable() {

@Override

public void run() {

while (true) {

reloadJarFile();

}

}

private void reloadJarFile() {

try {

System.out.println(" -- Reloading the jar file from the web !");

   String classToLoad = "org.apache.commons.lang3.StringUtils";

   URL jarUrl = new URL("jar:http://archiva/archiva/repository/internal/org/apache/commons/commons-lang3/3.1/commons-lang3-3.1.jar!/");

   URLClassLoader cl = new URLClassLoader(new URL[] {jarUrl}, null);

   Class loadedClass = cl.loadClass(classToLoad);

   

   Method method = loadedClass.getMethod("trim", new Class[] {java.lang.String.class});

   Object reloadMe = loadedClass.getConstructor().newInstance();

   String trimmedString = (String) method.invoke(reloadMe, new Object[]{"           1 2 3 4 5 6          "});

System.out.println(" -- Trimmed string is : {" + trimmedString + "}");

} catch (Exception e) {

e.printStackTrace();

}

}

};

startReloader(r);

}

private static void startReloader(Runnable r) {

try {

Thread reloader = new Thread(r);

reloader.start();

reloader.join();

} catch (InterruptedException e) {

e.printStackTrace();

}

}

}