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微信公众号第三方平台的开放，让公众号运营者在面向垂直行业需求时，可以通过一键登录授权给第三方开发者，来完成相关的处理能力，方便快捷，那如何才能开发出一个公众号第三方平台供一键授权呢？本文以JAVA作为后台服务的实现语言，实现了微信第三方开放平台开发所需要的主要业务流程，并针对全网发布的检测做了相应的代码处理，以通过微信全网检测，可以接入任意的微信公众号。
根据微信第三方平台的审核需求，你需要在微信开放平台上注册第三方平台信息时，提供如下几个主要的服务：
1、 授权事件接收服务 ，对应填写的审核资料中授权事件接收URL，微信会将相关的授权事件信息推送到该REST服务上，推送的主要消息包括验证票据ComponentVerifyTicket和取消授权的公众号AuthorizerAppid，该服务需要对微信推送过来的该类消息立即做出回应并返回success内容，该服务事件的JAVA实现方式如下：
/*** 授权事件接收* * @param request* @param response* @throws IOException* @throws AesException* @throws DocumentException*/@RequestMapping(value = "/open/event/authorize", method = RequestMethod.POST)@ResponseStatus(HttpStatus.NO_CONTENT)public void acceptAuthorizeEvent(HttpServletRequest request, HttpServletResponse response) throws IOException, AesException, DocumentException {WeixinOpenService.getInstance().processAuthorizeEvent(request);WeixinOpenService.getInstance().output(response, "success"); // 输出响应的内容。}
更具体的实现代码如下：
/*** 处理授权事件的推送* * @param request* @throws IOException* @throws AesException* @throws DocumentException*/public void processAuthorizeEvent(HttpServletRequest request) throws IOException, DocumentException, AesException {String token = WeixinOpenService.TOKEN;String nonce = request.getParameter("nonce");String timestamp = request.getParameter("timestamp");String signature = request.getParameter("signature");String msgSignature = request.getParameter("msg_signature");if (!StringUtils.isNotBlank(msgSignature))return;// 微信推送给第三方开放平台的消息一定是加过密的，无消息加密无法解密消息boolean isValid = WechatCallbackServiceController.checkSignature(token, signature, timestamp, nonce);if (isValid) {StringBuilder sb = new StringBuilder();BufferedReader in = request.getReader();String line;while ((line = in.readLine()) != null) {sb.append(line);}String xml = sb.toString();String encodingAesKey = WeixinOpenService.ENCODINGAESKEY;// 第三方平台组件加密密钥String appId = getAuthorizerAppidFromXml(xml, "authorizationEvent");// 此时加密的xml数据中ToUserName是非加密的，解析xml获取即可WXBizMsgCrypt pc = new WXBizMsgCrypt(token, encodingAesKey, appId);xml = pc.decryptMsg(msgSignature, timestamp, nonce, xml, "AppId");processAuthorizationEvent(xml);}}
2、 公众号消息与事件接收服务 ，对应填写的审核资料中公众号消息与事件接收URL，微信会将粉丝发送给公众号的消息和事件推送到该REST服务上，微信公众平台要求该消息和事件接收服务在5秒内做出回应，如果5秒内微信公众平台得不到响应消息，粉丝将将收到提示公众号暂时服务提供服务的错误信息。对于需要对粉丝发送的消息走人工渠道做出响应的公众号来说，此时就需要首先接收下消息，将消息交给后来逻辑转人工处理，然后立即以空格消息响应微信公众平台，微信收到空格消息后就会知道该粉丝发送的消息已经被妥善处理，并对该响应不做任何处理，同时不会发起消息重新推送的重试。该服务的JAVA实现实现方式如下：
/*** 处理微信推送过来的授权公众号的消息及事件* */public void processMessageAndEvent(HttpServletRequest request,String xml) throws IOException, AesException, DocumentException {String nonce = request.getParameter("nonce");String timestamp = request.getParameter("timestamp");String msgSignature = request.getParameter("msg_signature");String encodingAesKey = WeixinOpenService.ENCODINGAESKEY;String token = WeixinOpenService.TOKEN;WXBizMsgCrypt pc = new WXBizMsgCrypt(token, encodingAesKey, PONENT_APPID);xml = pc.decryptMsg(msgSignature, timestamp, nonce, xml, "ToUserName");WechatCallbackServiceController.processMessage(xml);}
以上是开发微信第三方开发平台的主要服务代码，想要通过微信全网接入检测并成功发布，还有如下的工作的需要做：
开发一个体验页，可以直接让审核人员体验，因为需要的是直接体验，所以访问该页面就不要有认证和权限控制之类的逻辑了，这个页面要求符合微信第三方平台基本的设计要求，本人简单实现了如下的页面格式是可以成功通过审核的，如下：
针对微信全网检测的固定账号做出特定的响应，主要包括一个文本消息响应，一个事件消息响应和一个客服接口调用验证，微信全网检测要求测试的固定账号接收到以上消息后，分别做出如下的响应：接收到TESTCOMPONENT_MSG_TYPE_TEXT这样的文本消息立即回复给粉丝文本内容TESTCOMPONENT_MSG_TYPE_TEXT_callback；接收到事件消息，立即以文本内容的消息格式回复粉丝内容event + “from_callback”，其中event需要根据实际内容替换为具体事件类型；接收到QUERY_AUTH_CODE:query_auth_code 这样的文本消息，需要立即响应空字符串给微信，之后调用客服接口回复粉丝文本消息，内容为：$query_auth_code\$_from_api，其中query_auth_code需要替换为微信实际推送过来的数据。主要的JAVA后台实现代码如下：
/*** 公众号消息与事件接收* * @param request* @param response* @throws DocumentException* @throws AesException* @throws IOException*/@RequestMapping(value = "/open/{appid}/callback", method = RequestMethod.POST)@ResponseStatus(HttpStatus.NO_CONTENT)public void acceptMessageAndEvent(HttpServletRequest request, HttpServletResponse response) throws IOException, AesException, DocumentException {String msgSignature = request.getParameter("msg_signature");if (!StringUtils.isNotBlank(msgSignature))return;// 微信推送给第三方开放平台的消息一定是加过密的，无消息加密无法解密消息StringBuilder sb = new StringBuilder();BufferedReader in = request.getReader();String line;while ((line = in.readLine()) != null) {sb.append(line);}in.close();String xml = sb.toString();Document doc = DocumentHelper.parseText(xml);Element rootElt = doc.getRootElement();String toUserName = rootElt.elementText("ToUserName");if (StringUtils.equalsIgnoreCase(toUserName, "gh_3c884a361561")) {// 微信全网测试账号WeixinWholeNetworkTestService.getInstance().checkWeixinAllNetworkCheck(request,response,xml);}else{WeixinOpenService.getInstance().processMessageAndEvent(request,xml);WeixinOpenService.getInstance().output(response, "");}}
其中gh_3c884a361561这个账号是微信全网接入检测的固定账号，针对全网检测需要对该账号做特出响应，一旦全网接入检测通过，这部分的代码是可以去掉的，只有全网检测的时候才需要这部分代码。
public void checkWeixinAllNetworkCheck(HttpServletRequest request, HttpServletResponse response,String xml) throws DocumentException, IOException, AesException{String nonce = request.getParameter("nonce");String timestamp = request.getParameter("timestamp");String msgSignature = request.getParameter("msg_signature");String encodingAesKey = WeixinOpenService.ENCODINGAESKEY;String token = WeixinOpenService.TOKEN;WXBizMsgCrypt pc = new WXBizMsgCrypt(token, encodingAesKey, PONENT_APPID);xml = pc.decryptMsg(msgSignature, timestamp, nonce, xml, "ToUserName");Document doc = DocumentHelper.parseText(xml);Element rootElt = doc.getRootElement();String msgType = rootElt.elementText("MsgType");String toUserName = rootElt.elementText("ToUserName");String fromUserName = rootElt.elementText("FromUserName");switch (msgType) {case "event":String event = rootElt.elementText("Event");replyEventMessage(request,response,event,toUserName,fromUserName);break;case "text":String content = rootElt.elementText("Content");processTextMessage(request,response,content,toUserName,fromUserName);break;default:break;}}
根据消息或事件类型区分后，剩余的逻辑只需要处理成对应的回复内容即可，如下：
public void replyEventMessage(HttpServletRequest request, HttpServletResponse response, String event, String toUserName, String fromUserName) throws DocumentException, IOException {String content = event + "from_callback";replyTextMessage(request,response,content,toUserName,fromUserName);}public void processTextMessage(HttpServletRequest request, HttpServletResponse response,String content,String toUserName, String fromUserName) throws IOException, DocumentException{if("TESTCOMPONENT_MSG_TYPE_TEXT".equals(content)){String returnContent = content+"_callback";replyTextMessage(request,response,returnContent,toUserName,fromUserName);}else if(StringUtils.startsWithIgnoreCase(content, "QUERY_AUTH_CODE")){WeixinOpenService.getInstance().output(response, "");//接下来客服API再回复一次消息replyApiTextMessage(request,response,content.split(":")[1],fromUserName);}}public void replyApiTextMessage(HttpServletRequest request, HttpServletResponse response, String auth_code, String fromUserName) throws DocumentException, IOException {String authorization_code = auth_code;// 得到微信授权成功的消息后，应该立刻进行处理！！相关信息只会在首次授权的时候推送过来WeixinOpenData weixinOpenData = WeixinOpenService.getInstance().getWeixinOpenData(PONENT_APPID);long accessTokenExpires = weixinOpenData.getAccessTokenExpires();String componentAccessToken = weixinOpenData.getComponentAccessToken();String componentVerifyTicket = weixinOpenData.getComponentVerifyTicket();JSONObject authorizationInfoJson;if (!this.isExpired(accessTokenExpires)) {authorizationInfoJson = WeixinOpenService.getInstance().apiQueryAuth(componentAccessToken, PONENT_APPID, authorization_code);} else {JSONObject accessTokenJson = WeixinOpenService.getInstance().getComponentAccessToken(PONENT_APPID, PONENT_APPSECRET, componentVerifyTicket);componentAccessToken = accessTokenJson.getString("component_access_token");authorizationInfoJson = WeixinOpenService.getInstance().apiQueryAuth(componentAccessToken, PONENT_APPID, authorization_code);}if (log.isDebugEnabled()) {log.debug("weixinopen callback authorizationInfo is " + authorizationInfoJson);}JSONObject infoJson = authorizationInfoJson.getJSONObject("authorization_info");String authorizer_access_token = infoJson.getString("authorizer_access_token");String url = "https://api./cgi- ... ot%3B + authorizer_access_token;DefaultHttpClient client = new DefaultHttpClient();enableSSLDefaultHttpClient(client);HttpPost httpPost = new HttpPost(url);JSONObject message = processWechatTextMessage(client, httpPost, fromUserName, auth_code + "_from_api");if(log.isDebugEnabled()){log.debug("api reply messto to weixin whole network test respose = "+message);}} public void replyTextMessage(HttpServletRequest request, HttpServletResponse response, String content, String toUserName, String fromUserName) throws DocumentException, IOException {Long createTime = Calendar.getInstance().getTimeInMillis() / 1000;StringBuffer sb = new StringBuffer();sb.append("");sb.append("");sb.append("");sb.append("" + createTime + "");sb.append("");sb.append("");sb.append("");String replyMsg = sb.toString();String returnvaleue = "";try {WXBizMsgCrypt pc = new WXBizMsgCrypt(WeixinOpenService.TOKEN, WeixinOpenService.ENCODINGAESKEY, PONENT_APPID);returnvaleue = pc.encryptMsg(replyMsg, createTime.toString(), "easemob");} catch (AesException e) {log.error("auto reply to weixin whole network test occur exception = "+ e);e.printStackTrace();}if(log.isDebugEnabled()){log.debug("return weixin whole network test Text message is = "+returnvaleue);}WeixinOpenService.getInstance().output(response, returnvaleue);}
以上是微信第三方开放平台开发主要的业务流程，在实际开发中，还有两点需要特别注意：
1、微信要求第三方开放平台必须以密文方式接收消息；
2、在实际部署时，需要更换JAVA安全包相关的内容，否则将出现秘钥长度不够的异常，需要替换的文件包括JAVA_HOME/jre/lib/security/local_policy.jar和 JAVA_HOME/jre/lib/security/US_export_policy.jar这两个文件。
