Java security MD5加密算法

利用java.security对字符串进行MD5加密：

 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;

 public class MD5 {
     public static final String MD5CODE = "";

     private static MessageDigest messageDigest = null;

     public static String Encode(final String Source) {
         return Encode(Source + MD5CODE, null);
     }

     public static String Encode(final String Source, final String charset) {
         if (Source == null)
             return null;
         if (messageDigest == null) {
             try {
                 messageDigest = MessageDigest.getInstance("MD5");
             } catch (NoSuchAlgorithmException e) {
                 return null;
             }
         }
         if (charset == null || charset.trim().length() <= 0){
             messageDigest.update(Source.getBytes());
             }else {
             try {
                 messageDigest.update(Source.getBytes(charset));
             } catch (Exception e) {
                 messageDigest.update(Source.getBytes());
             }
         }
         byte[] digesta = messageDigest.digest();
         return Bytes2Hex(digesta);
     }

     public static byte[] EncodeBytes(byte[] Source) {
         if (messageDigest == null) {
             try {
                 messageDigest = MessageDigest.getInstance("MD5");
             } catch (NoSuchAlgorithmException e) {
                 return null;
             }
         }
         messageDigest.update(Source);
         byte[] ret = messageDigest.digest();
         return ret;
     }

     public static String Bytes2Hex(final byte[] Source) {
         String hs = "";
         String stmp = "";
         for (int n = 0; n < Source.length; n++) {
             stmp = (java.lang.Integer.toHexString(Source[n] & 0xFF));
             if (stmp.length() == 1)
                 hs = hs + "0" + stmp;
             else
                 hs = hs + stmp;
         }
         return hs;
     }

     public static void main(String args[]) {

         String str = "123456";
         String encode = MD5.Encode(str);
         String encode1 = MD5.Encode(str);
         String encode2 = MD5.Encode(str);
         System.out.println("MD5.encode 123456="+encode+"---"+encode1+"---"+encode2);

     }
 }