public class CryptoUtil {
    private static Key DEFAULT_KEY;
    /**
     * 預設金鑰
     */
    private static final String DEFAULT_SECRET_KEY = "1qaz2wsx3edc$RFV%TGB^YHN&UJM";
    /**
     * 加密模式
     */
    private static final String DES = "DES";
    /**
     * 加密解密格式
     */
    private static final String format = "DES/ECB/PKCS5Padding";
 

    /**
     * 優先載入獲得key
     */
    static {
        DEFAULT_KEY = obtainKey(DEFAULT_SECRET_KEY);
    }

    /**
     * 獲得key
     **/
    private static Key obtainKey(String key) {
        //如果key等於null 使用預設金鑰
        if (key == null) {
            return DEFAULT_KEY;
        }
        KeyGenerator generator = null;
        try {
 
            generator = KeyGenerator.getInstance(DES);
            //防止linux下 隨機生成key
            SecureRandom secureRandom = SecureRandom.getInstance("SHA1PRNG");
            secureRandom.setSeed(key.getBytes("UTF-8"));
            generator.init(secureRandom);
        } catch (Exception e) {
            e.printStackTrace();
 
        }

        return generator.generateKey();
    }



    /**
     * null key 加密 使用預設金鑰加密
     * String明文輸入,String密文輸出
     */
    public static String encode(String str) {
        return encode(null, str);
    }

    /**
     * 加密
     * String明文輸入,String密文輸出
     */
    public static String encode(String key, String str) {
        return Base64.encodeBase64URLSafeString(obtainEncode(key, str.getBytes()));
        // return Hex.encodeHexString(obtainEncode(key, str.getBytes()));
        // 可以轉化為16進位制資料
    }

    /**
     * null key 解密 使用預設金鑰解密
     * 以String密文輸入,String明文輸出
     */
    public static String decode(String str) {
        return decode(null, str);
    }

    /**
     * 解密
     * 以String密文輸入,String明文輸出
     */
    public static String decode(String key, String str) {
        return new String(obtainDecode(key, Base64.decodeBase64(str)));
        // 可以轉化為16進位制的資料
//      try {
//          return new String(obtainDecode(key, Hex.decodeHex(str.toCharArray())));
//      } catch (DecoderException e) {
//          // TODO Auto-generated catch block
//          e.printStackTrace();
//      }
    }


    /**
     * 底層加密方法
     * 以byte[]明文輸入,byte[]密文輸出
     */
    private static byte[] obtainEncode(String key, byte[] str) {
        byte[] byteFina = null;
        Cipher cipher;
        try {
            Key key1 = obtainKey(key);
            cipher = Cipher.getInstance(format);
            cipher.init(Cipher.ENCRYPT_MODE, key1);
            byteFina = cipher.doFinal(str);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return byteFina;
    }

    /**
     * 底層解密方法
     * 以byte[]密文輸入,以byte[]明文輸出
     */
    private static byte[] obtainDecode(String key, byte[] str) {
        Cipher cipher;
        byte[] byteFina = null;
        try {
            Key key1 = obtainKey(key);
            cipher = Cipher.getInstance(format);
            cipher.init(Cipher.DECRYPT_MODE, key1);
            byteFina = cipher.doFinal(str);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return byteFina;
    }

    public static void main(String[] args) {
        String key = "wellsoft.cc";
        String content = "234234234234234324";
        System.out.println("加密前：" + content);
        String a = CryptoUtil.encode(key, content);
        System.out.println("加密後：" + a);
        String b = CryptoUtil.decode(key, a);
        System.out.println("解密後：" + b);
    }


}