问为何通过code获取openid失败？

	/**
	 * 通过Code获取微信OpenID
	 * 
	 * @param code
	 * @return
	 * @throws Exception
	 */
	private String getOpenID(String code) throws Exception {
		// System.out.println("code" + code);
        String url = "https://api.weixin.qq.com/sns/jscode2session";
        url += "?appid=" + AppID;//自己的appid
        url += "&secret=" + Secret;//自己的appSecret
        url += "&js_code=" + code;
        url += "&grant_type=authorization_code";
        url += "&connect_redirect=1";
        String res = null;
        CloseableHttpClient httpClient = HttpClientBuilder.create().build();
        // DefaultHttpClient();
        HttpGet httpget = new HttpGet(url);    //GET方式
        CloseableHttpResponse response = null;
        // 配置信息
        RequestConfig requestConfig = RequestConfig.custom()          // 设置连接超时时间(单位毫秒)
                .setConnectTimeout(5000)                    // 设置请求超时时间(单位毫秒)
                .setConnectionRequestTimeout(5000)             // socket读写超时时间(单位毫秒)
                .setSocketTimeout(5000)                    // 设置是否允许重定向(默认为true)
                .setRedirectsEnabled(false).build();           // 将上面的配置信息 运用到这个Get请求里
        httpget.setConfig(requestConfig);                         // 由客户端执行(发送)Get请求
        response = httpClient.execute(httpget);                   // 从响应模型中获取响应实体
        HttpEntity responseEntity = response.getEntity();
        // System.out.println("响应状态为:" + response.getStatusLine());
        if (responseEntity != null) {
            res = EntityUtils.toString(responseEntity);
            // System.out.println("响应内容长度为:" + responseEntity.getContentLength());
            // System.out.println("响应内容为:" + res);
        }
        // 释放资源
        if (httpClient != null) {
            httpClient.close();
        }
        if (response != null) {
            response.close();
        }
        JSONObject jo = JSON.parseObject(res);
        String openid = jo.getString("openid");
        // System.out.println("openid" + openid);
		return openid;
	}