调用微信支付的接口 https://api.mch.weixin.qq.com/pay/unifiedorder

传参数sign

sign是WXPayUtil.generateSignature方法获取的 提示“签名错误” 这是为啥啊

String sign = WXPayUtil.generateSignature(params, apiKey);
System.out.println(sign);
// 创建XML字符串
String xmlData = XmlUtil.createXml(appId, mchId, nonceStr, body, outTradeNo, totalFee, spbillCreateIp, notifyUrl, tradeType);
xmlData = xmlData.replace("YOUR_SIGN_HERE", sign);
System.out.println(xmlData);
// 发送POST请求
String requestUrl = "https://api.mch.weixin.qq.com/pay/unifiedorder";
HttpURLConnection connection = (HttpURLConnection) new URL(requestUrl).openConnection();
connection.setRequestMethod("POST");
connection.setRequestProperty("Content-Type", "application/xml; charset=UTF-8");
connection.setDoOutput(true);