类加载器及加密问题 - 黑马程序员技术交流社区

import java.util.Date;
public class ClassLoaderTest {
/**
* @param args
* @throws ClassNotFoundException
* @throws IllegalAccessException
* @throws InstantiationException
*/
public static void main(String[] args) throws ClassNotFoundException, InstantiationException, IllegalAccessException {
// TODO Auto-generated method stub
Class clazz=new MyClassLoader("xiaodai").loadClass("ClassLoaderDai");//问题为什么这里不调用findClass()函数呢？而调用
Date date=(Date)clazz.newInstance(); //
loaderClass （）方法呢？调用父类的
loaderClass 方法
如
System.out.println(date); //何将”ClassLoaderDai“传给子类的呢？子类有如何用的
} //呢？
}

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import java.io.ByteArrayOutputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
public class MyClassLoader extends ClassLoader{
/**
* @param args
* @throws IOException
*/
public static void main(String[] args) throws IOException {
// TODO Auto-generated method stub
String readFile=args[0];
String writefiles=args[1];
String file=readFile.substring(readFile.lastIndexOf("\\")+1);
String writefile=writefiles+"\\"+file;
InputStream is=new FileInputStream(readFile);
OutputStream os=new FileOutputStream(writefile);
cyper(is,os);
is.close();
os.close();
}
public static void cyper(InputStream is,OutputStream os) throws IOException{
int ips=-1;
while((ips=is.read())!=-1){
os.write(ips^0xff);
}
}
@Override
protected java.lang.Class<?> findClass(String name) throws ClassNotFoundException {
String readFile=classpaty+"\\"+name+".class";
try {
InputStream is=new FileInputStream(readFile);
ByteArrayOutputStream os=new ByteArrayOutputStream();
cyper(is,os);
is.close();
byte[] b=os.toByteArray();
return defineClass(b, 0, b.length);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
private String classpaty;
MyClassLoader(){
}
MyClassLoader(String classpaty){
this.classpaty=classpaty;
}
}

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