使用微信官方服务端SDK微信APP支付提示支付签名验证失败

这两天APP微信支付后端代码更换为微信官方的java版SDK（java_sdk_v3.0.9），更换之后APP端发起支付提示支付签名有问题，最后查看SDK源码发现，原来签名方式有问题，记得以前公司老代码加密方式都是MD5，一直是没问题的。官方的SDK只有在沙盒环境下才是MD5加密方式，最后不得不修改SDK源码，手动设置签名方式为MD5。异步回调验签方法默认是MD5的。

com.github.wxpay.sdk.WXPay类中加了两个重载构造方法：

    // 原有的构造方法
    public WXPay(final WXPayConfig config) throws Exception {
        this(config, null, true, false);
    }

    // 新增的构造方法
    public WXPay(final WXPayConfig config, SignType signType) throws Exception {
        this(config, null, true, false, signType);
    }

    // 原有的构造方法
    public WXPay(final WXPayConfig config, final String notifyUrl,
            final boolean autoReport, final boolean useSandbox)
            throws Exception {
        this.config = config;
        this.notifyUrl = notifyUrl;
        this.autoReport = autoReport;
        this.useSandbox = useSandbox;
        if (useSandbox) {
            this.signType = SignType.MD5; // 沙箱环境
        } else {
            this.signType = SignType.HMACSHA256;
        }
        this.wxPayRequest = new WXPayRequest(config);
    }

    // 新增的构造方法
    public WXPay(final WXPayConfig config, final String notifyUrl,
            final boolean autoReport, final boolean useSandbox,
            SignType signType) throws Exception {
        this.config = config;
        this.notifyUrl = notifyUrl;
        this.autoReport = autoReport;
        this.useSandbox = useSandbox;
        this.signType = signType;
        this.wxPayRequest = new WXPayRequest(config);
    }

/**
     * APP，统一下单,获取预支付ID
     * 
     * https://pay.weixin.qq.com/wiki/doc/api/app/app.php?chapter=9_1
     * 
     * @param outTradeNo
     * @param totalFee
     *            元
     * @param notifyUrl
     * @param ipaddress
     * @return
     */
    public String getPrepayId(WXPay wxpay, String outTradeNo, String totalFee,
            String notifyUrl, String ipaddress) {
        String totalFeeFen = AmountUtils.changeY2F(totalFee);
        String prepayId = null;
        Map data = new HashMap();
        data.put("body", outTradeNo);
        data.put("out_trade_no", outTradeNo);
        data.put("total_fee", totalFeeFen);
        data.put("spbill_create_ip", ipaddress);
        data.put("notify_url", notifyUrl);
        data.put("trade_type", TradeTypeEnum.APP.name());
        try {
            Map resp = wxpay.unifiedOrder(data);
            if (ReturnCodeEnum.SUCCESS.name().equals(resp.get("return_code"))) {
                prepayId = resp.get("prepay_id");
            } else {
                System.err.println("微信统一下单失败:");
                System.err.println(resp);
            }
        } catch (Exception e) {
            System.err.println("微信统一下单异常！");
            e.printStackTrace();
        }
        return prepayId;
    }

    /**
     * 调起支付接口
     * 
     * https://pay.weixin.qq.com/wiki/doc/api/app/app.php?chapter=9_12&index=2
     * 
     * @param outTradeNo
     * @param totalFee
     *            人民币 CNY 元
     * @param notifyUrl
     * @param ipaddress
     * @return
     * @throws Exception
     */
    public Record requestWxpay(String outTradeNo, String totalFee,
            String notifyUrl, String ipaddress) throws Exception {
        Record payData = null;
        AppConfig config = AppConfig.getInstance();
        WXPay wxpay = new WXPay(config, SignType.MD5);//指定签名方式为MD5!!!!!!!!!!!!!!
        String prepayId = getPrepayId(wxpay, outTradeNo, totalFee, notifyUrl,
                ipaddress);
        if (StringUtils.isNotBlank(prepayId)) {
            Map params = new HashMap();
            String appid = config.getAppID();
            params.put("appid", appid);
            params.put("noncestr", WXPayUtil.generateNonceStr());
            params.put("package", "Sign=WXPay");
            params.put("partnerid", config.getMchID());
            params.put("prepayid", prepayId);
            params.put("timestamp", config.getTimestamp());
            String sign = WXPayUtil.generateSignature(params, config.getKey(),
                    SignType.MD5);//指定签名方式为MD5!!!!!!!!!!!!!!
            params.put("sign", sign);
            payData = new Record();
            payData.set("data", params);
        }
        return payData;
    }