<?xml version="1.0" encoding="ISO-8859-1"?>

<classes>

 <class name="User">

 <method>say</method>

 </class> 

 <class name="map">

 <method>add</method>

 </class> 

</classes>

package dx;

public class map {

    public void add(){

        System.out.println("1+1=2");

    }

}

package cn.fjs;

public class User {

    public void say(){

        System.out.println(" hello ...");

    }

}

package cn.fjs;

import java.io.ByteArrayOutputStream;

import java.io.File;

import java.io.FileInputStream;

public class DynamicClassLoader extends ClassLoader{

    private static final String SUFFIX = ".class";

    public String[] paths;

    public DynamicClassLoader(String[] paths) {

        this.paths = paths;

    }

    public DynamicClassLoader(ClassLoader parent,String[] paths){

        super(parent);

        this.paths = paths;

    }

    @SuppressWarnings("deprecation")

    @Override

    protected Class<?> findClass(String className) throws ClassNotFoundException {

        String classPath = getClassPath(className);

        if(classPath != null){

            byte[] clazz = loadClazz(classPath);

            return defineClass(clazz, 0, clazz.length);

        }else{

            System.out.println("class is not found !");

            return null;

        }

    }

    public byte[] loadClazz(String classPath) {

        try {

            FileInputStream in = new FileInputStream(new File(classPath));

            ByteArrayOutputStream baos = new ByteArrayOutputStream();

            int b;

            while((b = in.read()) != -1){

                baos.write(b);

            }

            in.close();

            return baos.toByteArray();

        } catch (Exception e) {

            System.out.println(e);

        }

        return null;

    }

    public String getClassPath(String className){

        for(String path : paths){

            if(className.contains(".")){

                className = className.replaceAll(".", File.separator);

            }

            String classPath = path + className + SUFFIX;

            File classFile = new File(classPath);

            if(classFile.exists()){

                return classPath;

            }

        }

        return null;

    }

}

package cn.fjs;

import java.io.IOException;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import javax.xml.parsers.DocumentBuilder;

import javax.xml.parsers.DocumentBuilderFactory;

import javax.xml.parsers.ParserConfigurationException;

import org.w3c.dom.Document;

import org.w3c.dom.Element;

import org.w3c.dom.Node;

import org.w3c.dom.NodeList;

import org.xml.sax.SAXException;

//解析xml文件，获取类和方法

public class DynamicDom {

    private static DocumentBuilderFactory dbFactory = null;

    private static DocumentBuilder db = null;

    private static Document document = null;  

    static{

        try {

            dbFactory = DocumentBuilderFactory.newInstance();

            db = dbFactory.newDocumentBuilder();

        } catch (ParserConfigurationException e) {

            e.printStackTrace();

        }

    }  

    public Map<String,List<String>> getMethods(String fileName) throws SAXException, IOException{

        Map<String,List<String>> classes = new HashMap<String, List<String>>();

        document = db.parse(fileName);

        NodeList nList = document.getElementsByTagName("class");

        for(int i = 0 ; i<nList.getLength();i++){

            Node node = nList.item(i);

            Element ele = (Element)node;

            if(node.getNodeType() == Element.ELEMENT_NODE){

              String clazz = ele.getAttribute("name");

              List<String> methods = new ArrayList<String>();

              String method = ele.getElementsByTagName("method").item(0).getTextContent();

              methods.add(method);

              classes.put(clazz, methods);

            }

        }

        return classes;

    }

}

package cn.fjs;

import java.util.List;

import java.util.Map;

import cn.fjs.DynamicClassLoader;

import cn.fjs.DynamicDom;

public class DynamicClassLoaderTest {

    public static void main(String[] args) {

        DynamicDom dmo = new DynamicDom();//xml文件解析类

        Map<String, List<String>> classes;

        //重载ClassLoader类

        DynamicClassLoader loader = new DynamicClassLoader(new String[]{"D:\\tmp\\"});

        try {

            classes = dmo.getMethods("D:\\tmp\\a.xml");

            for(String key:classes.keySet()){

                for(String clazz : classes.get(key)){

                    Class<?> c =loader.findClass(key);//类名字

                    c.getMethod(clazz).invoke(c.newInstance());//方法名字

                }

            }

        }catch (Exception e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        }

    }

}