小程序授权解密

这个是需要拿到解密的密钥 微信登录拿到的code
String url = "https://api.weixin.qq.com/sns/jscode2session?appid=" + appId + "&secret=" + secret + "&js_code=" + code + "&grant_type=authorization_code";
String getResult = Https.sendGet(url, "", false);
WXKey bean = new Gson().fromJson(getResult, WXKey.class);
String decrypt = new String(AESWX.decrypt(encryptedData, bean.getSession_key(), iv), "UTF-8");

decrypt 最终要的答案

下面是AESWX：

public class AESWX {
    // 算法名称
    final static String KEY_ALGORITHM = "AES";

    // 加解密算法/模式/填充方式
    final static String algorithmStr = "AES/CBC/PKCS7Padding";
    //
    private static Key key;
    private static Cipher cipher;

    public static void init(byte[] keyBytes) {

        // 如果密钥不足16位，那么就补足. 这个if 中的内容很重要
        int base = 16;
        if (keyBytes.length % base != 0) {
            int groups = keyBytes.length / base + (keyBytes.length % base != 0 ? 1 : 0);
            byte[] temp = new byte[groups * base];
            Arrays.fill(temp, (byte) 0);
            System.arraycopy(keyBytes, 0, temp, 0, keyBytes.length);
            keyBytes = temp;
        }
        // 初始化
        Security.addProvider(new BouncyCastleProvider());
        // 转化成JAVA的密钥格式
        key = new SecretKeySpec(keyBytes, KEY_ALGORITHM);
        try {
            // 初始化cipher
            cipher = Cipher.getInstance(algorithmStr);
        } catch (NoSuchAlgorithmException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (NoSuchPaddingException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    /**
     * 解密方法
     *
     * @param encryptedData
     *            要解密的字符串
     * @param keyBytes
     *            解密密钥
     * @return
     */
    public static byte[] decrypt(String encryptedDataStr, String keyBytesStr, String ivStr) {
        byte[] encryptedText = null;
        byte[] encryptedData = null;
        byte[] sessionkey = null;
        byte[] iv = null;

        try {
            sessionkey = Base64.decodeBase64(keyBytesStr);
            encryptedData = Base64.decodeBase64(encryptedDataStr);
            iv = Base64.decodeBase64(ivStr);

            init(sessionkey);

            cipher.init(Cipher.DECRYPT_MODE, key, new IvParameterSpec(iv));
            encryptedText = cipher.doFinal(encryptedData);
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return encryptedText;
    }