学步园

JAVA中MD5算法实现函数,此函数生成的字符串(MD5)跟本博客中的C语言生成的完全一样，这个可以方便实现替换。

private static String md5(String input) {
  if ( (input == null) || (input.length() == 0) ){
   return "D41D8CD98F00B204E9800998ECF8427E";     //这个值是为了兼容C语言的DLL MD5值而存在
  }
  else{
   StringBuffer sb = new StringBuffer();
   try {
    MessageDigest algorithm = MessageDigest.getInstance("MD5");
    algorithm.reset();
    algorithm.update(input.getBytes());
    byte[] md5 = algorithm.digest();
    String singleByteHex = "";
    for (int i = 0; i < md5.length; i++) {
     singleByteHex = Integer.toHexString(0xFF & md5[i]);
     if (singleByteHex.length() == 1) {
      sb.append("0");
     }
     sb.append(singleByteHex.toUpperCase());
    }
   } catch (NoSuchAlgorithmException ex) {
    ex.printStackTrace();
   }
   return sb.toString();
  }
 }