md5

MD5是一种常用的加密算法，在项目中经常用到，我参考了网上一些实例。贴出来MD5加密、解密代码。希望大侠多指导。。。。

package com.test;

import java.security.MessageDigest;

public class MD5andKL {
	 // MD5加码。32位
	 public static String MD5(String inStr) {
	  MessageDigest md5 = null;
	  try {
	   md5 = MessageDigest.getInstance("MD5");
	  } catch (Exception e) {
	   System.out.println(e.toString());
	   e.printStackTrace();
	   return "";
	  }
	  char[] charArray = inStr.toCharArray();
	  byte[] byteArray = new byte[charArray.length];

	  for (int i = 0; i < charArray.length; i++)
	   byteArray[i] = (byte) charArray[i];

	  byte[] md5Bytes = md5.digest(byteArray);

	  StringBuffer hexValue = new StringBuffer();

	  for (int i = 0; i < md5Bytes.length; i++) {
	   int val = ((int) md5Bytes[i]) & 0xff;
	   if (val < 16)
	    hexValue.append("0");
	   hexValue.append(Integer.toHexString(val));
	  }

	  return hexValue.toString();
	 }

	 // 可逆的加密算法
	 public static String KL(String inStr) {
	  // String s = new String(inStr);
	  char[] a = inStr.toCharArray();
	  for (int i = 0; i < a.length; i++) {
	   a[i] = (char) (a[i] ^ 't');
	  }
	  String s = new String(a);
	  return s;
	 }

	 // 加密后解密
	 public static String JM(String inStr) {
	  char[] a = inStr.toCharArray();
	  for (int i = 0; i < a.length; i++) {
	   a[i] = (char) (a[i] ^ 't');
	  }
	  String k = new String(a);
	  return k;
	 }
	 
	 // 测试主函数
	 public static void main(String args[]) {
	  String s = new String("a");
	  System.out.println("原始：" + s);
	  System.out.println("MD5后：" + MD5(s));
	  System.out.println("MD5后再加密：" + KL(MD5(s)));
	  System.out.println("解密为MD5后的：" + JM(KL(MD5(s))));
	  System.out.println("解密为MD5：" + JM(KL(s)));

	 }
	}