本文将带你了解微信开发微信跨公众号支付，希望本文对大家学微信有所帮助。

先说下我的需求。我有两个公众号（不是订阅号，订阅号无法向公众号支付）分别为A和B，现在我关注公众号A，在公众号A中需要发起公众号B的支付，也就是说我在公众号A中向公众号B支付钱（用户未关注B公众号）。

一、在公众号B中配置测试授权目录

二、使用微信OAuth2.0授权公众号B获取B公众号openId

/**       * 微信授权获取code     * @param   response     * @throws IOException     */      @RequestMapping(value = "/getCode", produces =   {"application/json;charset=UTF-8"}, method =   RequestMethod.GET)    public void   getCode(HttpServletResponse response) throws IOException {          response.sendRedirect(getCodeRequest());    }      public static String    GetCodeRequest =   "https://open.weixin.qq.com/connect/oauth2/authorize?appid=APPID&redirect_uri=REDIRECT_URI&response_type=code&scope=SCOPE&state=STATE#wechat_redirect";    public static String   getCodeRequest(){        String result   = null;        GetCodeRequest  = GetCodeRequest.replace("APPID",   urlEnodeUTF8(WxpayConfig.appid));          //授权回调地址weixin/t1/callBack处理code获取openId        GetCodeRequest  =   GetCodeRequest.replace("REDIRECT_URI",urlEnodeUTF8("//xxxxxx/weixin/t1/callBack"));          //不弹出微信授权页面：scope=snsapi_base，弹出微信授权页面：scope=snsapi_userinfo        GetCodeRequest =   GetCodeRequest.replace("SCOPE", "snsapi_base");        result = GetCodeRequest;        return result;      }

三、授权完成,授权回调函数获取code和openId

/** 微信授权回调  **/ @RequestMapping(value = "/callBack",   produces = {"application/json;charset=UTF-8"}, method =   RequestMethod.GET)    public String   callBack(HttpServletRequest request) throws IOException {        //獲取code        String code =   request.getParameter("code");          String url = String.format(Constant.OPENID_RETREIVAL_URL,   WxpayConfig.appid, WxpayConfig.appsecret, code); //获取openId信息 JSONObject   jsonObject = WeixinUtil.httpsRequest(url, "GET", null);        if (jsonObject != null) {            try {                OpenIdBean openIdBean =   (OpenIdBean) JSONObject.toBean(jsonObject, OpenIdBean.class);                  request.setAttribute("openId",openIdBean.getOpenid());            }catch (Exception e) {                e.printStackTrace();            }        } //跳转到发起支付的页面        return   "weixin/test/index2";      }

至此已经在A公众号中完全获取了B公众号的OpenId下面就可以进行支付了。

附index2页面

四、统一下单进行支付

//公众号支付      @RequestMapping(value = "/unifiedorder_jsapi", produces =   {"application/json;charset=UTF-8"}, method =   RequestMethod.GET)      @ResponseBody    public Object   native_unifiedOrder2(HttpServletRequest request){          //终端设备号(门店号或收银设备ID)，注意：PC网页或公众号内支付请传"WEB"        String device_info =   "WEB";          //随机字符串，不长于32位        String   nonce_str =   UUID.randomUUID().toString().replace("-","");        //商品或支付单简要描述        //String body =   request.getParameter("body");          //商品名称明细列表        String detail   = request.getParameter("detail");        //商户系统内部的订单号        String orderNos =   request.getParameter("orderNos");        //APP和网页支付提交用户端ip，Native支付填调用微信支付API的机器IP        String spbill_create_ip =   request.getParameter("spbill_create_ip");        //交易类型   取值如下：JSAPI--公众号支付，NATIVE:扫码支付，APP          String trade_type = "JSAPI";        //用户openid        String openid =   request.getParameter("openId");        //组装请求数据        TreeMaptreeMap = new TreeMap();          treeMap.put("appid",WxpayConfig.appid);        treeMap.put("mch_id",   WxpayConfig.mch_id);          treeMap.put("nonce_str", nonce_str);          treeMap.put("notify_url",WxpayConfig.notify_url);          treeMap.put("device_info",device_info);        treeMap.put("body","asadsd");          treeMap.put("detail","ssss");          treeMap.put("spbill_create_ip","192.167.0.12");        treeMap.put("trade_type",   trade_type);          treeMap.put("openid",openid);        Map resMap = new HashMap();        //创建TradingOrder订单与支付单关系表        String out_trade_no =   UUID.randomUUID().toString().replace("-", "");        //转换订单号，主要是为了应对多单合并支付        treeMap.put("out_trade_no",   out_trade_no);          //计算订单的实际支付金额          //订单总金额，单位为分        //付款金额必须为整数   不允许有小数点          treeMap.put("total_fee", "1");        String xml =   WxUtil.getPackage(treeMap);        //   创建HttpClientBuilder          HttpClientBuilder httpClientBuilder = HttpClientBuilder.create();        CloseableHttpClient closeableHttpClient   = httpClientBuilder.build();          HttpPost httpPost = new HttpPost(WxpayConfig.unifiedorder);        StringEntity entity;        //预支付id        String prepay_id ="";        //当trade_type为NATIVE获取扫码支付连接        String code_url = "";        try {            entity = new StringEntity(xml,   "utf-8");              httpPost.setEntity(entity);              CloseableHttpResponse httpResponse;            // post请求            httpResponse =   closeableHttpClient.execute(httpPost);            HttpEntity httpEntity =   httpResponse.getEntity();            if   (httpEntity != null) {                  // 打印响应内容                String   result = EntityUtils.toString(httpEntity, "UTF-8");                // 过滤                result = result.replaceAll("",   "");                  Mapmap =   XMLUtil.doXMLParse(result);                  if(map != null){                      prepay_id  = (String)   map.get("prepay_id");                  }            }            // 释放资源            closeableHttpClient.close();        } catch (Exception e) {            e.printStackTrace();        }          //获取prepay_id后，拼接最后请求支付所需要的package        if(prepay_id == null ||   "".equals(prepay_id)    ){//请求数据出错              resMap.put("payMsg",new HashMap());        }else {            TreeMapfinalpackage = new TreeMap();              String timestamp = WxUtil.getTimeStamp();            String packages =   "prepay_id="+prepay_id;              finalpackage.put("appId", WxpayConfig.appid);              finalpackage.put("timeStamp", timestamp);              finalpackage.put("nonceStr", nonce_str);              finalpackage.put("package", packages);            finalpackage.put("signType",   "MD5");            String   paySign = WxUtil.createSign(finalpackage);              finalpackage.put("paySign",paySign);            resMap.put("payMsg",   finalpackage);        }        //请求数据无误，可生成预支付订单写入数据库        return resMap;      }
至此跨公众号支付就完成了，在上面的代码中用到了一些工具类，可根据自己去修改。

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