java MD5加密解密

package com.md5;/**  * @author 作者 E-mail: [e-mail] * @version 创建时间：2012-11-6 下午3:29:45  * 类说明  */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后的值：" + JM(JM(s)));// 一次加密两次解密}}