java的MD5加密与解密

方法一：只加密

 

import java.security.*; import java.security.spec.*; class MD5_test { public final static String MD5(String s) { char hexDigits[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' }; try { byte[] strTemp = s.getBytes(); MessageDigest mdTemp = MessageDigest.getInstance("MD5"); mdTemp.update(strTemp); byte[] md = mdTemp.digest(); int j = md.length; char str[] = new char[j * 2]; int k = 0; for (int i = 0; i < j; i++) { byte byte0 = md[i]; str[k++] = hexDigits[byte0 >>> 4 & 0xf]; str[k++] = hexDigits[byte0 & 0xf]; } return new String(str); } catch (Exception e) { return null; } } public static void main(String[] args) { // MD5_Test aa = new MD5_Test(); System.out.print(MD5_test.MD5("b")); } }   

 

 

方法二：加密与解密

 

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)))); } }   

参考自：http://happymen001.javaeye.com/blog/576388