Java后台获取微信小程序用户信息、openid

/**
 * 获取微信小程序 session_key 和 openid
 *
 * @param code 调用微信登陆返回的Code
 * @return
 */
public static JSONObject getSessionKeyOropenid(String code) {
    //微信端登录code值
    String wxCode = code;
    Locale locale = new Locale("en", "US");
    ResourceBundle resource = ResourceBundle.getBundle("config/wx-config",locale);   //读取属性文件
    String requestUrl = resource.getString("url");  //请求地址 https://api.weixin.qq.com/sns/jscode2session
    Map<String, String> requestUrlParam = new HashMap<String, String>();
    requestUrlParam.put("appid", resource.getString("appId"));  //开发者设置中的appId
    requestUrlParam.put("secret", resource.getString("appSecret")); //开发者设置中的appSecret
    requestUrlParam.put("js_code", wxCode); //小程序调用wx.login返回的code
    requestUrlParam.put("grant_type", resource.getString("grantType"));    //默认参数 authorization_code

    //发送post请求读取调用微信 https://api.weixin.qq.com/sns/jscode2session 接口获取openid用户唯一标识
    JSONObject jsonObject = JSON.parseObject(sendPost(requestUrl, requestUrlParam));
    return jsonObject;
}

/**
 * 向指定 URL 发送POST方法的请求
 *
 * @param url 发送请求的 URL
 * @return 所代表远程资源的响应结果
 */
public static String sendPost(String url, Map<String, ?> paramMap) {
    PrintWriter out = null;
    BufferedReader in = null;
    String result = "";

    String param = "";
    Iterator<String> it = paramMap.keySet().iterator();

    while (it.hasNext()) {
        String key = it.next();
        param += key + "=" + paramMap.get(key) + "&";
    }

    try {
        URL realUrl = new URL(url);
        // 打开和URL之间的连接
        URLConnection conn = realUrl.openConnection();
        // 设置通用的请求属性
        conn.setRequestProperty("accept", "*/*");
        conn.setRequestProperty("connection", "Keep-Alive");
        conn.setRequestProperty("Accept-Charset", "utf-8");
        conn.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
        // 发送POST请求必须设置如下两行
        conn.setDoOutput(true);
        conn.setDoInput(true);
        // 获取URLConnection对象对应的输出流
        out = new PrintWriter(conn.getOutputStream());
        // 发送请求参数
        out.print(param);
        // flush输出流的缓冲
        out.flush();
        // 定义BufferedReader输入流来读取URL的响应
        in = new BufferedReader(new InputStreamReader(conn.getInputStream(), "UTF-8"));
        String line;
        while ((line = in.readLine()) != null) {
            result += line;
        }
    } catch (Exception e) {
        log.error(e.getMessage(), e);
    }
    //使用finally块来关闭输出流、输入流
    finally {
        try {
            if (out != null) {
                out.close();
            }
            if (in != null) {
                in.close();
            }
        } catch (IOException ex) {
            ex.printStackTrace();
        }
    }
    return result;
}

 /**
     * 解密用户敏感数据获取用户信息
     *
     * @param sessionKey    数据进行加密签名的密钥
     * @param encryptedData 包括敏感数据在内的完整用户信息的加密数据
     * @param iv            加密算法的初始向量
     * @return
     * */
    public static JSONObject getUserInfo(String encryptedData, String sessionKey, String iv) {
        // 被加密的数据
        byte[] dataByte = Base64Util.decodeByte(encryptedData);
        // 加密秘钥
        byte[] keyByte = Base64Util.decodeByte(sessionKey);
        // 偏移量
        byte[] ivByte = Base64Util.decodeByte(iv);
        try {

            // 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 (keyByte.length % base != 0) {
                int groups = keyByte.length / base + (keyByte.length % base != 0 ? 1 : 0);
                byte[] temp = new byte[groups * base];
                Arrays.fill(temp, (byte) 0);
                System.arraycopy(keyByte, 0, temp, 0, keyByte.length);
                keyByte = temp;
            }
            // 初始化
            Security.addProvider(new BouncyCastleProvider());
            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7Padding", "BC");
            SecretKeySpec spec = new SecretKeySpec(keyByte, "AES");
            AlgorithmParameters parameters = AlgorithmParameters.getInstance("AES");
            parameters.init(new IvParameterSpec(ivByte));
            cipher.init(Cipher.DECRYPT_MODE, spec, parameters);// 初始化
            byte[] resultByte = cipher.doFinal(dataByte);
            if (null != resultByte && resultByte.length > 0) {
                String result = new String(resultByte, "UTF-8");
                return JSON.parseObject(result);
            }
        } catch (NoSuchAlgorithmException e) {
            log.error(e.getMessage(), e);
        } catch (NoSuchPaddingException e) {
            log.error(e.getMessage(), e);
        } catch (InvalidParameterSpecException e) {
            log.error(e.getMessage(), e);
        } catch (IllegalBlockSizeException e) {
            log.error(e.getMessage(), e);
        } catch (BadPaddingException e) {
            log.error(e.getMessage(), e);
        } catch (UnsupportedEncodingException e) {
            log.error(e.getMessage(), e);
        } catch (InvalidKeyException e) {
            log.error(e.getMessage(), e);
        } catch (InvalidAlgorithmParameterException e) {
            log.error(e.getMessage(), e);
        } catch (NoSuchProviderException e) {
            log.error(e.getMessage(), e);
        }
        return null;
    }