支付寶支付成功跳轉(zhuǎn)到NotifyUrl時(shí)候報(bào)錯(cuò)，如何解決？

public String getSign(AlipayTradeModel alipayTradeModel) throws AlipayApiException {

        //實(shí)例化客戶端
        AlipayClient alipayClient = new DefaultAlipayClient(
                serverUrl,
                appId,
                appPrivateKey,
                format,
                charset,
                alipayPublicKey,
                signType);

        //實(shí)例化具體API對(duì)應(yīng)的request類,類名稱和接口名稱對(duì)應(yīng),當(dāng)前調(diào)用接口名稱：alipay.trade.app.pay
        AlipayTradeAppPayRequest request = new AlipayTradeAppPayRequest();
        //SDK已經(jīng)封裝掉了公共參數(shù)，這里只需要傳入業(yè)務(wù)參數(shù)。以下方法為sdk的model入?yún)⒎绞?model和biz_content同時(shí)存在的情況下取biz_content)。
        AlipayTradeAppPayModel model = new AlipayTradeAppPayModel();
        model.setBody(alipayTradeModel.getBody());
        model.setSubject(alipayTradeModel.getSubject());
        model.setOutTradeNo(alipayTradeModel.getOutTradeNo());
        model.setTimeoutExpress(alipayTradeModel.getTimeoutExpress());
        model.setTotalAmount(alipayTradeModel.getTotalAmount());
        model.setProductCode(alipayTradeModel.getProductCode());

        request.setBizModel(model);
        request.setNotifyUrl(notifyUrl);//alipay.notify_url=http://www.your_rul.com/alipay/notify
        //這里和普通的接口調(diào)用不同，使用的是sdkExecute
        AlipayTradeAppPayResponse response = alipayClient.sdkExecute(request);
        System.out.println(response.getBody());//就是orderString 可以直接給客戶端請(qǐng)求，無(wú)需再做處理。
        return response.getBody();
    }

 Error, exception=com.alipay.api.AlipayApiException, message=RSAcontent = ,sign=null,charset = utf-8, path=/alipay/notify}] as "application/json;charset=utf-8" using [org.springframework.http.converter.json.MappingJackson2HttpMessageConverter@2f01783a]