密码加密

public class MD5 {
public static String getMD5Str(String str) {
        MessageDigest messageDigest = null;

        try {
            messageDigest = MessageDigest.getInstance("MD5");

            messageDigest.reset();

            messageDigest.update(str.getBytes("UTF-8"));
        } catch (NoSuchAlgorithmException e) {
//            System.out.println("NoSuchAlgorithmException caught!");
            System.exit(-1);
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }

        byte[] byteArray = messageDigest.digest();

        StringBuffer md5StrBuff = new StringBuffer();

        for (int i = 0; i < byteArray.length; i++) {            
            if (Integer.toHexString(0xFF & byteArray[i]).length() == 1)
                md5StrBuff.append("0").append(Integer.toHexString(0xFF & byteArray[i]));
            else
                md5StrBuff.append(Integer.toHexString(0xFF & byteArray[i]));
        }

        return md5StrBuff.toString();
    }
}