MD5加密源码！

import java.security.*;

class MD5{
 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;
  }
 }
}