MD5__java应用

public final static String encode(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;    }  }