java 动态加载的实现代码

public abstract class AbstractAction {   public abstract String action(); } public class TestAction extends AbstractAction{   public String action() {     System.out.println("I am working ! ");     return "this ActionTest class";   } }

 String s = "file://D:/Style.jar";***//jar所在的文件的URL* URL url = new URL(s); URLClassLoader myClassLoader = new URLClassLoader(new URL[] { url }, Thread.currentThread() .getContextClassLoader()); Class<? extends AbstractAction> myClass = (Class<? extends AbstractAction>) myClassLoader.loadClass("com.java.jarloader.TestAction"); AbstractAction action = (AbstractAction) myClass.newInstance(); String str = action.action(); System.out.println(str);