微信公众号支付，获取openId

1. 获取code
1.1关注公众号后采用https://open.weixin.qq.com/connect/qrconnect
https://open.weixin.qq.com/connect/qrconnect?appid=wxd01b****c55a&redirect_uri=my-***.com%2fcheckout%2fcart&response_type=code&scope=snsapi_base&state=STATE#wechat_redirect

1.2 h5网页版采用
https://open.weixin.qq.com/connect/oauth2/authorize?appid=wx87a****09713&redirect_uri=http%3A%2F%2F10.88.75.139%3A8082%2Fpay%2Fwechat.htm&response_type=code&scope=snsapi_base&state=1#wechat_redirect

2.根据appid，secret，code获取openId
详细见http://572327713.iteye.com/blog/2388251

	/*
	 * (non-Javadoc)
	 * @see com.baozun.store.manager.wechat.WechatAccessTokenService#getOpenIdByAccessTokenUrl(java.lang.String, java.lang.String)
	 */
	@Override
	public String getOpenIdByAccessTokenUrl(String code,String authType){
		// 用来存储用户的openid
		String openid = "";
		// 过滤无效数据
		if (StringUtils.isBlank(code) || StringUtils.isBlank(authType)){
			return null;
		}
		// 构建accessTokenUrl
		String accessTokenUrl = this.buildGetAccessTokenUrl(authType, code);
		LOGGER.debug("wechat get access token url is {}", accessTokenUrl);

		// 从接口中取出accessToken数据
		String json = HttpUtils.doGetReq(accessTokenUrl);
		
		JSONObject jsonobject = JSONObject.fromObject(json);

		// 如果调用接口成功，不会出现Errcode值
		if (Validator.isNullOrEmpty(jsonobject.get("errcode"))){
			openid = jsonobject.get("openid").toString();
			LOGGER.info("##  Get access token success,open_id is [{}]", openid);
		}else{
			LOGGER.error(
					"##  Get access token failed, status code is:[{}],errmsg is:[{}]",
					jsonobject.get("errcode"),
					jsonobject.get("errmsg"));
		}
		return openid;
	}

	/*
	 * (non-Javadoc)
	 * @see com.baozun.store.manager.wechat.WechatAccessTokenService#buildGetAccessTokenUrl(java.lang.String)
	 */
	@Override
	public String buildGetAccessTokenUrl(String oAuthType,String code){
		//顺序链接获取微信code的url配置参数，转换于url地址
		Map<String,String> connectionParam=new LinkedHashMap<String, String>();
		connectionParam.put("appid", appId);
		connectionParam.put("secret", appSecret);
		
		String getAccessTokenUrl;

		// 根据授权方式选择不同url地址链接 （链接参数地址的顺序不能改变）
		if (WechatConstants.AUTH_TYPE_2.equalsIgnoreCase(oAuthType) || WechatConstants.AUTH_TYPE_3.equalsIgnoreCase(oAuthType)){
			connectionParam.put("code", code);
			connectionParam.put("grant_type", WechatConstants.GRANT_TYPE_AUTHORIZATION_CODE);
			getAccessTokenUrl=ParamUtil.addParameterSingleValueMap(oAuthAccessTokenUrl, connectionParam, null);
		}else{
			connectionParam.put("grant_type", WechatConstants.GRANT_TYPE_CLIENT_CREDENTIAL);
			getAccessTokenUrl=ParamUtil.addParameterSingleValueMap(globalAccessTokenUrl, connectionParam, null);
		}
		LOGGER.info("-------buildGetAccessTokenUrl of [{}]",getAccessTokenUrl);
		return getAccessTokenUrl;
	}