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import java.io.ByteArrayOutputStream;

import java.io.File;

import java.io.FileInputStream;

import java.io.InputStream;

public class MyClassLoader extends ClassLoader{

private String name;//the binary name of a class

private String path="D:\\";

private final String fileExtendName=".class";

public MyClassLoader(String name){

super();//让系统类加载器成为该类加载器的父加载器

this.name=name;

}

public MyClassLoader(ClassLoader parent,String name){

super(parent);//

this.name=name;

}

public String getPath() {

return path;

}

public void setPath(String path) {

this.path = path;

}

public String toString() {

return this.name;

}

private byte[] loadClassData(String name){

InputStream is=null;

byte[] data=null;

ByteArrayOutputStream baos=null;

try{

this.name=this.name.replace('.', '\\');

is=new FileInputStream(new File(

path+name+fileExtendName));

int ch=0;

baos=new ByteArrayOutputStream();

while(-1!=(ch=is.read())){

baos.write(ch);

}

data=baos.toByteArray();

}

catch(Exception e){e.printStackTrace();}

finally{

try{

is.close();

baos.close();

}

catch(Exception e){e.printStackTrace();}

}

return data;

}

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

byte[] data=loadClassData(name);

return this.defineClass(name, data, 0, data.length);

}

public static void main(String[] args) throws Exception {

MyClassLoader loader1=new MyClassLoader("loader1");

loader1.setPath("f:\\test\\loader1\\");

MyClassLoader loader2=new MyClassLoader(loader1,"loader2");

loader2.setPath("f:\\test\\loader2\\");

MyClassLoader loader3=new MyClassLoader(null,"loader3");

loader3.setPath("f:\\test\\loader3\\");

test(loader2);

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

test(loader3);

}

public static void test(ClassLoader c) throws Exception{

Class clazz=c.loadClass("Sample");

Object o=clazz.newInstance();

}

}