微信小程式——支付

1.通過code獲取openId

code：使用者登入憑證（有效期五分鐘）。開發者需要在開發者伺服器後臺呼叫 api，使用 code 換取 openid 和 session_key 等資訊
openid： 使用者唯一標識
session_key: 會話金鑰

2.構建統一下單引數，傳送微信客戶端

/**
     * 構建統一下單引數，發給微信伺服器
     * 
     * @param tradeType
     * @param body
     * @param tradeNo 訂單號
     * @param ip
     * @return
 

     */
    private UnifiedOrderRequestData constructData(
            String tradeNo, 
            int totalFee,
            String ip, 
            String openid) {
        UnifiedOrderRequestData data = new UnifiedOrderRequestData.
                UnifiedOrderReqDataBuilder(
                WeixinConstant.FEBDA_PAY_BODY, tradeNo, totalFee, ip,
                WeixinConstant.TRADE_TYPE).setOpenid(openid).build();
        // 產生簽名信息
 

        data.setSign(WxPayUtil.getSign(data));
        return data;
    }

/**
     * 利用反射獲取Java物件的欄位並進行加密，過濾掉sign欄位
     * @param data
     * @return
     * return:String
     */
    public static String getSign(Object data) {
        StringBuilder stringA = new StringBuilder();
        Map<String
 
, String> map = new HashMap<String, String>();
        Field[] fields = data.getClass().getDeclaredFields();
        Method[] methods = data.getClass().getDeclaredMethods();
        for (Field field : fields) {
            String fieldName = field.getName();
            if (field != null && !fieldName.equals("sign")) {
                String getMethodName = "get" + fieldName.substring(0,1).toUpperCase() + fieldName.substring(1);
                for (Method method : methods) {
                    if (method.getName().equals(getMethodName)) {
                        try {
                            if (method.invoke(data, new Object[]{}) != null && method.invoke(data, new Object[]{}).toString().length() != 0) {
                                map.put(fieldName, method.invoke(data, new Object[]{}).toString());
                            }
                        } catch (IllegalAccessException | IllegalArgumentException
                                | InvocationTargetException e) {
                            e.printStackTrace();
                        }
                    }
                }
            }
        }
        List<Map.Entry<String,String>> mappingList = null; 
        //通過ArrayList建構函式把map.entrySet()轉換成list 
        mappingList = new ArrayList<Map.Entry<String,String>>(map.entrySet()); 
        //通過比較器實現比較排序 
        Collections.sort(
            mappingList, 
            new Comparator<Map.Entry<String,String>>(){ 
                public int compare(Map.Entry<String,String> mapping1,Map.Entry<String,String> mapping2){ 
                    return mapping1.getKey().compareTo(mapping2.getKey()); 
                } 
            }
        );
        for (Map.Entry<String, String> mapping : mappingList) {
            stringA.append("&").append(mapping.getKey()).append("=").append(mapping.getValue());
        }
        String stringSignTemp = stringA.append("&key=").append(WeixinPayConfig.KEY).substring(1);
        return WeixinUtil.MD5(stringSignTemp).toUpperCase();
    }

/**
     * 呼叫微信統一下單介面,返回客戶端資料
     * 
     * @param tradeType
     *            JSAPI支付
     * @return UnifiedOrderResponseData
     */
    private UnifiedOrderResponseData unifiedOrder(String userId, String proId,
            int price, String ip, String openid,String type,String orderId) { // proId 問題id
        if(Strings.isNullOrEmpty(ip)){
             InetAddress addr = null;
            try {
                addr = InetAddress.getLocalHost();
            } catch (UnknownHostException e) {
                e.printStackTrace();
            }
              ip = addr.getHostAddress().toString();
        }
        /*if (PayApp.theApp.isDebug()) {// 測試時候支付一分錢，買入價值6塊的20分鐘語音
            price = 1;//1分錢
        }*/
        // 生成請求資料物件
        UnifiedOrderRequestData data = constructData(orderId, price, ip, openid);
        // 呼叫微信統一下單介面
        UnifiedOrderResponseData responseData = WxPayUtil.unifiedOder(data);
        return responseData;
    }