简单的class文件加密解密

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加密生成的class文件

package com.dasenlin.encrpt;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;/** * 测试取反操作 * @author Administrator * */public class EncriptUtil {    /**     * @param args     */    public static void main(String[] args) {        encrpt("E:/LearnJavaProjectText/myjava/HelloWorld.class","E:/LearnJavaProjectText/mytemp/HelloWorld.class");    }    /**     * 测试的是取反     * @param src     * @param dest     */    public static void encrpt(String src,String dest){        FileInputStream fis=null;        FileOutputStream fos=null;        try {            fis = new FileInputStream(src);            fos = new FileOutputStream(dest);            int temp =-1;            while((temp=fis.read())!=-1){                fos.write(temp^0xff);//读出的数据进行取反；            }        } catch (FileNotFoundException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }finally{            try {                if(null!=fis){                    fis.close();                }            } catch (IOException e) {                e.printStackTrace();            }        }    }}

解密加密后的class文件的类加载器

package com.dasenlin.encrpt;import java.io.ByteArrayOutputStream;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.IOException;import java.io.InputStream;/** * 解密的类加载器 * @author Administrator * */public class DecriptClassLoader extends ClassLoader {private String rootDir;    public DecriptClassLoader(String rootDir){        this.rootDir=rootDir;    }    @Override    protected Class<?> findClass(String name) throws ClassNotFoundException {        Class<?> c = findLoadedClass(name);        if(c!=null){            return c;        }else{            ClassLoader parent=this.getParent();            try {                c=parent.loadClass(name);            } catch (Exception e) {                //e.printStackTrace();            }    //双亲委托机制，委派给父类加载。            if(c!=null){                return c;            }else{                byte[]classData = getClassData(name);                if(classData==null){                    throw new ClassNotFoundException();                }else{                     c=defineClass(name,classData,0,classData.length);                }            }        }        return c;    }    private byte[] getClassData(String name) {        String path=rootDir+"/"+name.replace('.', '/')+".class";        InputStream is =null;        ByteArrayOutputStream baos = new ByteArrayOutputStream();        try {             is=new FileInputStream(path);             int temp =-1;                while((temp=is.read())!=-1){                    baos.write(temp^0xff);//读出的数据进行取反；            }            return baos.toByteArray();        } catch (FileNotFoundException e) {            e.printStackTrace();            return null;        } catch (IOException e) {            e.printStackTrace();        }finally{            if(is!=null){                try {                    is.close();                } catch (IOException e) {                    e.printStackTrace();                }            }        }        return null;    }}

测试

package com.dasenlin.encrpt;/** * 通过自定义的解密类加载器加载 * @author Administrator * */public class DemoLoad {    /**     * @param args     */    public static void main(String[] args) {        DecriptClassLoader loader = new DecriptClassLoader("E:/LearnJavaProjectText/mytemp/");        try {            Class<?> c =loader.loadClass("HelloWorld");            System.out.println(c);        } catch (ClassNotFoundException e) {            e.printStackTrace();        }    }}

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