JAVA动态加载JAR包执行程序

入口代码

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();

}

}

接口类

package dynamic.test;

public interface ICarFactory {

    public void makeCar();//等待实现的造车方法

}

实现类

//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");

}

}