MessageDigest

java.security
Class MessageDigest

java.lang.Object
  java.security.MessageDigestSpi
      java.security.MessageDigest 

 This MessageDigest class provides applications the functionality of a
 message digest algorithm, such as MD5 or SHA. 

 MessageDigest md = MessageDigest.getInstance("MD5");

 byte[] hashConde;

 md.update(number.getBytes());

 hashConde = md.digest(); 

byte[]	digest()           Completes the hash computation by performing final operations such as padding. 取的值須儲存為byte[] 型態

參考	http://caterpillar.onlyfun.net/Gossip/Encoding/String.html
byte[]	getBytes()           Encodes this String into a sequence of bytes using the platform's default charset, storing the result into a new byte array. 使用平台預設的編碼, 儲存為byte陣列

參考	http://www.dotblogs.com.tw/chhuang/archive/2011/01/19/20883.aspx
void	update(byte[] input)           Updates the digest using the specified array of bytes. 計算byte[] 的演算法的值（MessageDigest）