packagecom.doit.generate;publicclassGenerate{privateStringsupplementZero(StringbinaryStr){intlen=128-binaryStr.length();for(intm=0;m
package com.doit.generate;
public class Generate{
private String supplementZero(String binaryStr) {
int len = 128 - binaryStr.length();
for (int m = 0; m < len; m++) {
binaryStr = "0" + binaryStr;
}
return binaryStr;
}
private byte[] encrypt(String srcStr) {
char[] srcChar = srcStr.toCharArray();
String result = "";
for (int i = 0; i < srcChar.length; i++) {
char c = (char) (((byte) srcChar[i]) >>> 2);
c = (char) (c ^ Integer.MAX_VALUE);
c = (char) (((byte) c) << 3);
c = (char) (c ^ Integer.MIN_VALUE);
c = (char) (((byte) c) >>> 1);
c = (char) (c ^ 1025);
c = (char) (~c);
c = (char) (c ^ Integer.MAX_VALUE);
result += supplementZero(Long.toBinaryString(srcChar[i]));
}
return result.getBytes();
}
}
展开

import java.util.Base64;

public class Encryption {
	
	// 加密和解密只要offset一致即可
	public static final int offset = Integer.MIN_VALUE + 10086;
	
	// 加密
	public static String encryption(String s) {
		
		StringBuilder sb = new StringBuilder();
		
		for (int i = 0; i < s.length(); i++) {
			sb.append("" + (char)(((int)s.charAt(i)) + offset));
		}
		
		return new StringBuilder(Base64.getEncoder().encodeToString(new String(sb.toString()).getBytes())).reverse().toString();
	}
	
	// 解密
	public static String decryption(String s) {
		
		s = new String(Base64.getDecoder().decode(new StringBuilder(s).reverse().toString()));
		
		StringBuilder sb = new StringBuilder();
		
		for (int i = 0; i < s.length(); i++) {
			sb.append((char)(((int)s.charAt(i)) - offset));
		}
		
		return sb.toString();
	}

	public static void main(String[] args) {
		String str = "加密字符串";
        // 使用的时候可嵌套多层，嵌套越多密文越长
		System.out.println(encryption(encryption(str)));
		System.out.println(decryption(decryption(encryption(encryption(str)))));
	}
}


 

如果想看一下简单的类加载器怎么自定义，可以跳转简单自定义类加载器
自定义加密解密类加载器

测试简单的class文件加密解密（取反操作）。取反加密只是一个简单示例。
加密工具类（字节按位取反）
package com.feng.ClassTest;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

/**
 * 加密工具类
 * @author feng
 *
 */

public class EncrpUtil {
	
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		encrpt("E:\\myjava\\HelloWorld.class", "E:\\myjava\\temp\\HelloWorld.class");
	}
	
	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);	//异或，每个字节按位取反
			}
			
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			
			try {
				if(fis != null) {
					fis.close();
				}
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			
			try {
				if(fos != null) {
					fos.close();
				}
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			
		}
	}
}


解密类加载器
package com.feng.ClassTest;

import java.io.ByteArrayOutputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;

/**
 * 加载文件系统加密后的class字节码的类加载器
 * @author feng
 *
 */

public class DecreptClassLoader extends ClassLoader {
	
	private String rootDir;
	
	public DecreptClassLoader(String rootDir) {
		this.rootDir = rootDir;
	}
	
	@Override
	protected Class<?> findClass(String name) throws ClassNotFoundException {
		
		Class<?> c = null;
		
		byte[] classData = getClassData(name);	// 自定义方法获取类字节码
		if(classData == null) {
			throw new ClassNotFoundException();	// 如果字节数组为空，抛出异常
		} else {
			try {
				c = defineClass(name, classData, 0, classData.length);
			} catch (ClassFormatError e){	// 加载错误
				e.printStackTrace();
				c = null;
			}

		}
		
		return c;
		
	}
	
	private byte[] getClassData(String classname) {
		// 拼出类class文件地址
		String path = rootDir + "/" + classname.replace('.', '/') + ".class";
		
		InputStream fis = null;
		ByteArrayOutputStream baos = new ByteArrayOutputStream();
		try {
			fis = new FileInputStream(path);
			
			int temp = -1;
			while((temp = fis.read()) != -1) {
				baos.write(temp^0xff);	//异或，每个字节按位取反
			}
			
			return baos.toByteArray();
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
			
			return null;
		} finally {
			
			try {
				if(fis != null) {
					fis.close();
				}
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			
			try {
				if(baos != null) {
					baos.close();
				}
			} catch (IOException e) {
				e.printStackTrace();
			}
			
		}
		
	}
	
}


测试自定义解密类加载器
package com.feng.ClassTest;

public class Demo04 {
	
	public static void main(String[] args) throws ClassNotFoundException {

		//加密后的class文件，正常的类加载器 无法加载，会报FormatError错误
		//FileSystemClassLoader loader = new FileSystemClassLoader("E:\\myjava\\temp");
		//Class<?> c = loader.findClass("HelloWorld");
		//System.out.println(c);
		
		// 使用解密类加载器
		DecreptClassLoader loader = new DecreptClassLoader("E:\\myjava\\temp");
		Class<?> c = loader.loadClass("HelloWorld");
		System.out.println(c);
		
	}

}

简单自定义    字节加1  有用记得点个赞
package game01;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.channels.FileChannel;
import java.util.Scanner;

public class Tool {
	public static FileInputStream fis =null;
	public static FileOutputStream fos =null;
	public static long start;//计时
	public static long end; 
	public static String jiamilj = null;
	public static String jiemilj = null;
	public static FileChannel fc = null;//文件大小
	
	
	public static void main(String []args) throws IOException{
		
		Scanner in = new Scanner(System.in);
		System.out.println("你要加密还是解密：");
		String input = in.next();
		
		if(input.equals("加密")){
			
			Scanner in01 = new Scanner(System.in);
			System.out.println("你要加密的文件路径：（E:\\a.txt）:");
			String input01 = in01.next();
			System.out.println(input01);
			
			jiami(input01);
			System.out.println("加密成功，加密路径："+jiamilj);
			System.out.println("加密用时"+(end-start)+"毫秒");
			size(1);
			System.out.println("文件大小"+fc.size()+"Byte");
			fis.close();
			fos.close();
		}else{
			Scanner in02 = new Scanner(System.in);
			System.out.println("你要解密的文件路径：（E:\\b.txt）:");
			String input02 = in.next();
			jiemi(input02);
			System.out.println("解密成功,解密路径为："+jiemilj);
			System.out.println("解密密用时"+(end-start)+"毫秒");
			size(2);
			System.out.println("文件大小"+fc.size()+"Byte");
			fis.close();
			fos.close();
		}	
		
		
	}
	
	
	//加密
	public static void jiami(String input02) throws IOException{
		start = System.currentTimeMillis();
		in01(input02);
		end = System.currentTimeMillis();
	}
	//解密
	public static void jiemi(String input02) throws IOException{
		start = System.currentTimeMillis();
		in02(input02);
		end = System.currentTimeMillis();
	}
	
	
	//配套加密
	public static void in01(String input03) throws IOException{
		 fis = new FileInputStream(input03);		
		int i;  //核心代码  
		while((i=fis.read())!=-1){			
			out01(i);
		}
		
	}	
	public static void out01(int i) throws IOException{
		 fos = new FileOutputStream("E:\\b.txt",true);
		fos.write(i+1);	
		jiamilj = "E:\\b.txt";
	}
	
	
	//配套解密
	public static void in02(String input03) throws IOException{
		fis = new FileInputStream(input03);		
		int i;  //核心代码  
		while((i=fis.read())!=-1){
			out02(i);
		}	
	}
	public static void out02(int i) throws IOException{
		 fos = new FileOutputStream("E:\\c.txt",true);
		fos.write(i-1);	
		jiemilj = "E:\\c.txt";
	}
	
	//求文件大小
	public static void size(int s) throws FileNotFoundException{
		if(s==1){
			FileInputStream fis01 = new FileInputStream("E:\\b.txt");
			fc = fis01.getChannel();
		}else{
			FileInputStream fis01 = new FileInputStream("E:\\c.txt");
			fc = fis01.getChannel();
		}
		
	}

}