一：异步通知是支付宝回调商户的服务器，所以这个地址需要通过外网访问，在真实项目中都会有对应的服务器，但是在测试中只有使用内网穿透工具

推荐使用NATAPP-内网穿透 基于ngrok的国内高速内网映射工具

配置好内网穿透之后不要忘记在常量类中配置异步返回的地址

二：异步通知

@RequestMapping("/alpay")
@ResponseBody
public String alpay(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) {
    // 获取支付宝POST过来反馈信息
    Map<String, String> params = new HashMap<>();
    Map<String, String[]> requestParams = httpServletRequest.getParameterMap();
    for (String name : requestParams.keySet()) {
        String[] values = requestParams.get( name );
        StringBuilder valueStr = new StringBuilder();
        for (String value : values) {
            valueStr.append( value );
        }
        params.put( name, valueStr.toString() );
    }
    // 调用支付宝SDK进行验签
    boolean verifyResult = false;
    try {
        verifyResult = AlipaySignature.rsaCheckV1( params, constant.PublicKey, "UTF-8", "RSA2" );
    } catch (Exception e) {
        e.printStackTrace();
    }
    // 验签通过，则处理业务逻辑
    if (verifyResult) {
        System.out.println( "异步验证通过" );
            //支付
            String tradeStatus = params.get( "trade_status" );
            if (tradeStatus.equals( "TRADE_SUCCESS" )) {
                // 交易支付成功，处理支付成功的逻辑
                String orderId = params.get( "out_trade_no" );
                String tradeNo = params.get( "trade_no" );
                String total_amount = params.get( "total_amount" );
                System.out.println( "订单id：" + orderId );
                System.out.println( "流水号:" + tradeNo );
                System.out.println( "支付金额:" + total_amount );
//根据订单号调用查询接口，查询支付信息
                AlipayTradeQueryResponse query = query( params.get( "out_trade_no" ) );
//查询支付信息，获取支付金额和订单金额是否一致，一致就就修改订单状态
                String totalAmount = query.getTotalAmount();
                if (totalAmount.equals( total_amount )) {
                    boolean b = sysOrdersService.updateState( orderId );
                    System.out.println( "修改数据库订单状态是否成功：" + b );
                }
        
              }
            }
        return "success";
    } else {
        // 验签失败，记录日志或进行其他后续处理
        System.out.println( "异步验证失败" );
        return "failure";
    }
}

三：查询交易信息接口

 /**
     * 查询交易信息
     *
     * @param outTradeNo
     * @return
     */
    public static AlipayTradeQueryResponse query(String outTradeNo) {
        try {
            AlipayClient alipayClient = new DefaultAlipayClient(
                    constant.serverUrl,
                    constant.appId,
                    constant.privateKey,
                    constant.format,
                    constant.charset,
                    constant.PublicKey,
                    constant.signType );
            AlipayTradeQueryRequest request = new AlipayTradeQueryRequest();
            JSONObject bizContent = new JSONObject();
            bizContent.put( "out_trade_no", outTradeNo );
            request.setBizContent( bizContent.toString() );
            AlipayTradeQueryResponse response = alipayClient.execute( request );
            if (response.isSuccess()) {
                System.out.println( "调用查询接口成功" );
                return response;
            } else {
                System.out.println( "调用查询接口失败" );
            }
        } catch (AlipayApiException e) {
            e.printStackTrace();
        }
        return null;
    }

四：测试

查看支付宝是否调用异步通知接口，数据库状态是否修改

新建订单

控制台输出

数据库

状态修改成功