杨校老师带你来看看蚂蚁金服旗下产品：沙箱支付宝使用

<dependency>
    <groupId>com.alipay.sdk</groupId>
    <artifactId>alipay-sdk-java</artifactId>
    <version>3.3.49.ALL</version>
</dependency>

@Controller
public class PayController {
 
    private final String APP_ID = "应用的APPID";
    private final String APP_PRIVATE_KEY = "生成的应用私钥";
    private final String CHARSET = "UTF-8";
    private final String ALIPAY_PUBLIC_KEY = "支付宝公钥";
    //这是沙箱接口路径,正式路径为https://openapi.alipay.com/gateway.do
    private final String GATEWAY_URL ="https://openapi.alipaydev.com/gateway.do";
    private final String FORMAT = "JSON";
    //签名方式
    private final String SIGN_TYPE = "RSA2";
    //支付宝异步通知路径,付款完毕后会异步调用本项目的方法,必须为公网地址
    private final String NOTIFY_URL = "http://公网地址/notifyUrl";
    //支付宝同步通知路径,也就是当付款完毕后跳转本项目的页面,可以不是公网地址
    private final String RETURN_URL = "http://公网地址/returnUrl";
    
}

 @RequestMapping("alipay")
    public void alipay(HttpServletResponse httpResponse) throws IOException {
 
        Random r=new Random();
        //实例化客户端,填入所需参数
        AlipayClient alipayClient = new DefaultAlipayClient(GATEWAY_URL, APP_ID, APP_PRIVATE_KEY, FORMAT, CHARSET, ALIPAY_PUBLIC_KEY, SIGN_TYPE);
        AlipayTradePagePayRequest request = new AlipayTradePagePayRequest();
        //在公共参数中设置回跳和通知地址
        request.setReturnUrl(RETURN_URL);
        request.setNotifyUrl(NOTIFY_URL);
 
        //商户订单号，商户网站订单系统中唯一订单号，必填
        //生成随机Id
        String out_trade_no = UUID.randomUUID().toString();
        //付款金额，必填
        String total_amount =Integer.toString(r.nextInt(9999999)+1000000);
        //订单名称，必填
        String subject ="奥迪A8 2020款 A8L 60 TFSl quattro豪华型";
        //商品描述，可空
        String body = "尊敬的会员欢迎购买奥迪A8 2020款 A8L 60 TFSl quattro豪华型";
        request.setBizContent("{\"out_trade_no\":\""+ out_trade_no +"\","
                + "\"total_amount\":\""+ total_amount +"\","
                + "\"subject\":\""+ subject +"\","
                + "\"body\":\""+ body +"\","
                + "\"product_code\":\"FAST_INSTANT_TRADE_PAY\"}");
        String form = "";
        try {
            form = alipayClient.pageExecute(request).getBody(); // 调用SDK生成表单
        } catch (AlipayApiException e) {
            e.printStackTrace();
        }
        httpResponse.setContentType("text/html;charset=" + CHARSET);
        httpResponse.getWriter().write(form);// 直接将完整的表单html输出到页面
        httpResponse.getWriter().flush();
        httpResponse.getWriter().close();
    }
}

@RequestMapping(value = "/returnUrl", method = RequestMethod.GET)
public String returnUrl(HttpServletRequest request, HttpServletResponse response)
        throws IOException, AlipayApiException {
    System.out.println("=================================同步回调=====================================");
 
    // 获取支付宝GET过来反馈信息
    Map<String, String> params = new HashMap<String, String>();
    Map<String, String[]> requestParams = request.getParameterMap();
    for (Iterator<String> iter = requestParams.keySet().iterator(); iter.hasNext();) {
        String name = (String) iter.next();
        String[] values = (String[]) requestParams.get(name);
        String valueStr = "";
        for (int i = 0; i < values.length; i++) {
            valueStr = (i == values.length - 1) ? valueStr + values[i] : valueStr + values[i] + ",";
        }
        // 乱码解决，这段代码在出现乱码时使用
        valueStr = new String(valueStr.getBytes("utf-8"), "utf-8");
        params.put(name, valueStr);
    }
 
    System.out.println(params);//查看参数都有哪些
    boolean signVerified = AlipaySignature.rsaCheckV1(params, ALIPAY_PUBLIC_KEY, CHARSET, SIGN_TYPE); // 调用SDK验证签名
    //验证签名通过
    if(signVerified){
        // 商户订单号
        String out_trade_no = new String(request.getParameter("out_trade_no").getBytes("ISO-8859-1"), "UTF-8");
        
        // 支付宝交易号
        String trade_no = new String(request.getParameter("trade_no").getBytes("ISO-8859-1"), "UTF-8");
        
        // 付款金额
        String total_amount = new String(request.getParameter("total_amount").getBytes("ISO-8859-1"), "UTF-8");
        
        System.out.println("商户订单号="+out_trade_no);
        System.out.println("支付宝交易号="+trade_no);
        System.out.println("付款金额="+total_amount);
        
        //支付成功，修复支付状态
        payService.updateById(Integer.valueOf(out_trade_no));
        return "ok";//跳转付款成功页面
    }else{
        return "no";//跳转付款失败页面
    }
    
}