import java.security.*;

public class MD5
{
? private static MD5 md5 = null;
? private MD5(){}
? public static MD5 getInstance()
? {
??? if (md5 == null)
??? {
????? md5 = new MD5();
??? }
??? return md5;
? }

? /**
?? * Description:encrypt the String by "MD5"
?? * @param str String
?? * @return String
?? */
? public String calcMD5(String str)
? {
??? try
??? {
????? MessageDigest alga = MessageDigest.getInstance("MD5");
????? alga.update(str.getBytes());
????? byte[] digesta = alga.digest();
????? return byte2hex(digesta);
??? }
??? catch (Exception e)
??? {
????? //System.out.println(e.getMessage());
????? return null;
??? }
? }

? private String byte2hex(byte[] b)
? {
??? String hs = "";
??? String stmp = "";
??? for (int n = 0; n < b.length; n++)
??? {
????? stmp = (Integer.toHexString(b[n] & 0XFF));
????? if (stmp.length() == 1)
????? {
??????? hs = hs + "0" + stmp;
????? }
????? else
????? {
??????? hs = hs + stmp;
????? }
????? if (n < b.length - 1)
????? {
??????? hs = hs + "";
????? }
??? }
??? return hs;
? }
}