微信订阅号开发，获取openid的方式

需求：微信订阅号开发，点击微信自定义菜单，获取关注用户的openid，并且传到后台与前端页面

说明：订阅号无法直接获取关注用户的openid传到前端，只能通过微信开放平台将订阅号和服务号关联起来，获取用户的uionid，这样就可以确定当前操作的微信用户

场景：

1. 菜单类型为 view，创建view的代码：

// 网页跳转菜单
Map<String, String> menu1_1 = new HashMap<>();
menu1_1.put("type", "view");
menu1_1.put("name", "进入生态圈");
menu1_1.put("url", "http://域名/menu/auth?redirect_uri=http://域名/menu/index");

Controller 代码：

/**
* 授权入口：订阅号设置了业务域名后才会进入此方法
* @param request
* @param response
*/
@RequestMapping(value = "/auth",method = RequestMethod.GET)
@ResponseBody
public void auth(HttpServletRequest request, HttpServletResponse response) {
    try {

        Map<String, String[]> paramterMap = request.getParameterMap();
        log.info("auth click Parameter: [");
        paramterMap.forEach((k,v)->{
            log.info("key : " + k + "；value : " + Arrays.toString(v));
        });
        log.info("]");

        // 跳转的URL必须要做encode
        String redirectUrl = URLEncoder.encode(request.getParameter("redirect_uri"), SysConst.ENCODE_UTF8);

        // 使用服务号的appid授权获取用户基本信息，然后跳转到redirect_uri，跳转到redirect_uri后，回接收到code
        String authUrl = "https://open.weixin.qq.com/connect/oauth2/authorize?appid="+WeChatConfigDYH.APP_ID_FWH　　　　　　　　+"&redirect_uri="+redirectUrl　　　　　　　　+"&response_type=code&scope=snsapi_userinfo&state=STATE&connect_redirect=1#wechat_redirect";

        //跳转授权页面
        response.sendRedirect(authUrl);

    } catch (Exception e) {
        e.printStackTrace();
    }
}

/**
* 授权接口跳转uri入口
* @param request
* @param response
*/
@RequestMapping(value = "/index",method = RequestMethod.GET)
public String index(HttpServletRequest request, HttpServletResponse response) {
    try {
        Map<String, String[]> paramterMap = request.getParameterMap();
        log.info("view click Parameter: [");
        paramterMap.forEach((k,v)->{
            log.info("key : " + k + "；value : " + Arrays.toString(v));
        });
        log.info("]");

        String code = request.getParameter("code");
        log.debug("auth redirect_uri code = " + code);

        JSONObject weChatCode = _dataCache.getWeChatCode(code);
        if (weChatCode == null) {
            //通过code换取网页授权access_token（与基础支持中的access_token不同）
            String requestUrl = "https://api.weixin.qq.com/sns/oauth2/access_token?appid="+WeChatConfigDYH.APP_ID_FWH　　　　　　　　　　+"&secret="+WeChatConfigDYH.APP_SECRET_FWH　　　　　　　　　　+"&code="+code+"&grant_type=authorization_code";

            //返回信息：包含unionid，标志唯一用户
            String accessInfoStr = _restTemplate.getForObject(requestUrl, String.class);

            // 转化成JSONObject
            weChatCode = JSONObject.parseObject(accessInfoStr);

            // 存入缓存
            _dataCache.putWeChatCode(code, weChatCode);
        }

        log.debug(weChatCode.toString());

        // 微信unionid，唯一
        String unionid = weChatCode.getString("unionid");

        // 客户ID
        String fcustomerid495 = null;

        // 获取用户信息
        Customer customer = _customerService.findByUnionId(unionid);
        if (customer != null) {
            fcustomerid495 = customer.getFcustomerid495();
        }

        // 设置unionid和fcustomerid到前端
        request.setAttribute("unionid", unionid);
        request.setAttribute("fcustomerid", fcustomerid495);

    } catch (Exception e) {
        e.printStackTrace();
    }

    return "index";
}

2. 菜单类型为 click 创建代码：

// 按钮click
Map<String, String> menu1_1 = new HashMap<>();
menu1_1.put("type", "click");
menu1_1.put("name", "进入生态圈");
menu1_1.put("key", "self_edit");

Controller代码：

/**
* 写法二
* @param requestBody
* @param signature
* @param timestamp
* @param nonce
* @param openid
* @param encType
* @param msgSignature
* @return
*/
@RequestMapping(method = RequestMethod.POST)
public String post(HttpServletRequest request, HttpServletResponse response,
        @RequestBody String requestBody,
        @RequestParam("signature") String signature,
        @RequestParam("timestamp") String timestamp,
        @RequestParam("nonce") String nonce,
        @RequestParam("openid") String openid,
        @RequestParam(name = "encrypt_type", required = false) String encType,
        @RequestParam(name = "msg_signature", required = false) String msgSignature) {

    // 返回给微信加密后的消息
    String respMessageEncrypt = "";
    try {
        request.setCharacterEncoding("UTF-8");
        response.setCharacterEncoding("UTF-8");

        Map<String, String> encryptMap = MessageUtil.fromEncryptedMap(requestBody, timestamp, nonce, msgSignature);
        log.info("菜单事件：" + encryptMap.toString());

        // 消息处理
        respMessageEncrypt = _weChatMessageService.newsMessage(encryptMap);

    } catch (Exception e) {
        e.printStackTrace();
    } finally {

    }

    return respMessageEncrypt;
}

/**
* 处理消息发送：图文消息
* @param request
* @return 加密消息字符传
*/
public String newsMessage(Map<String, String> requestMap) {
    // 返回加密消息字符串
    String respMessageEncrypt = null;
    try {
        // 发送方帐号（open_id）
        String fromUserName = requestMap.get("FromUserName");
        // 公众帐号
        String toUserName = requestMap.get("ToUserName");

        // 根据openid获取客户信息
        String fcustomerid495 = null;
        Customer customer = _customerService.findByOpenId(fromUserName);
        if (customer != null) {
            fcustomerid495 = customer.getFcustomerid495();
        }

        // 设置链接消息
        NewsMessageResp newsMessage = new NewsMessageResp();
        newsMessage.setToUserName(fromUserName);
        newsMessage.setFromUserName(toUserName);
        newsMessage.setCreateTime(new Date().getTime());
        newsMessage.setMsgId(UUID.randomUUID().toString());
        newsMessage.setMsgType(WeChatConst.RESP_MESSAGE_TYPE_NEWS);
        newsMessage.setArticleCount("1");

        // Articles
        List<Article> articleList = new ArrayList<Article>();
        Article article = new Article();
        article.setTitle("生态圈链接");
        article.setDescription("点击进入【生态圈】");
        article.setPicUrl("http://域名/img/htlogo.png");
        article.setUrl("http://域名?openid=" + fromUserName + "&fcustomerid=" + fcustomerid495);
        articleList.add(article);
        newsMessage.setArticles(articleList);

        // 链接消息xml
        String respMessage = MessageUtil.newsMessageToXml(newsMessage);
        log.info("链接消息 = " + respMessage);

        // 消息加密
        WxCryptUtil wxCryptUtil = new WxCryptUtil();
        respMessageEncrypt = wxCryptUtil.encrypt(respMessage);
        log.info("加密后的链接消息 = " + respMessageEncrypt);

    } catch (Exception e) {
        e.printStackTrace();
    }

    return respMessageEncrypt;
}