java 反射，插件机制，简易插件

1 新建一个项目 iaction，并export为iaction.jar

package com.tianditu.iaction;

public interface IFly {
public void fly();
}

2 新建一个项目 action，引用上述jar包,并实现接口IFly

package com.tianditu.action;

import com.tianditu.iaction.IFly;

public class Firefly implements IFly {

@Override
public void fly() {
System.out.println("萤火虫在飞翔");
}

}

3 新建一个项目 exam，并引用iaction.jar包

package com.tianditu.exam;

import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;

import com.tianditu.iaction.IFly;

public class Program {

public static void main(String[] args) {

try {
URL url=new URL("file:c:/action.jar");//将action.jar放到某个位置
URLClassLoader myClassLoader=new URLClassLoader(new URL[]{url},Thread.currentThread().getContextClassLoader());
Class<?> myClass=myClassLoader.loadClass("com.tianditu.action.Firefly");//反射实例化
IFly firefly=(IFly)myClass.newInstance();
firefly.fly();

} catch (MalformedURLException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (InstantiationException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
}

}

}