import java.io.File;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import dynamic.test.ICarFactory;public class hello {
public static void main(String args[])
{System.out.println("Hello world");// JAR文件地址String jarName = "CarFactory.jar";ICarFactory icf=null;//命名空间 类名称String className="dynamic.test.BYDFactory";File file = new File(jarName);URL url=null;try {url = file.toURL();} catch (MalformedURLException e1) {// TODO Auto-generated catch block
        e1.printStackTrace();}URLClassLoader loader = new URLClassLoader(new URL[]{url});Class aClass=null;try {// 接口实例化aClass = loader.loadClass(className);} catch (ClassNotFoundException e) {// TODO Auto-generated catch block
        e.printStackTrace();}try {icf = (ICarFactory)aClass.newInstance();} catch (InstantiationException e) {// TODO Auto-generated catch block
        e.printStackTrace();} catch (IllegalAccessException e) {// TODO Auto-generated catch block
        e.printStackTrace();}icf.makeCar();
}
}

package dynamic.test;
public interface ICarFactory {public void makeCar();//等待实现的造车方法
}

//创建BMWFactory类，实现了ICarFactory
package dynamic.test;
public class BMWFactory implements ICarFactory {
//实现了ICarFactory的makeCar()方法
public void makeCar() {
System.out.println("BMWFactroy made a 宝马  for you");
}
}

//创建BYDFactory类，实现了ICarFactory
package dynamic.test;
public class BYDFactory implements ICarFactory {
//实现了ICarFactory的makeCar()方法
public void makeCar() {
System.out.println("BYDFactroy 生产  一辆  比亚迪  for you");
}
}