支付宝开发文档地址
(https://pay.weixin.qq.com/wiki/doc/api/jsapi.php?chapter=11_1)

支付宝参数配置

public class AliPayConfig {
    // 1.商户appid
    public static String APP_ID = "yourAppId";
    
    // 2.请求网关地址
    public static String SERVER_URL = "https://openapi.alipay.com/gateway.do";
    
    // 3.私钥
    public static String APP_PRIVATE_KEY = "yourAppPrivateKey";
    
    // 4.支付宝公钥
    public static String ALIPAY_PUBLIC_KEY = "yourAlipayPublicKey";
    
    // 5.服务器异步通知页面路径
    public static String ASY_URL = "yourAsyUrl";
    
    // 6.编码
    public static String CHARSET = "UTF-8";
    
    // 7.返回格式
    public static String FORMAT = "json";
    
    // 8.加密类型
    public static String SIGNTYPE = "RSA2"; 
}

创建订单

public static JSONObject createPayOrder(String orderId, String cost,
            String describe) {
        JSONObject ret = new JSONObject();
        // 实例化客户端
        AlipayClient alipayClient = new DefaultAlipayClient(
                AliPayConfig.SERVER_URL, AliPayConfig.APP_ID,
                AliPayConfig.APP_PRIVATE_KEY, AliPayConfig.FORMAT,
                AliPayConfig.CHARSET, AliPayConfig.ALIPAY_PUBLIC_KEY,
                AliPayConfig.SIGNTYPE);
        // 实例化具体API对应的request类,类名称和接口名称对应,当前调用接口名称：alipay.trade.app.pay
        AlipayTradeAppPayRequest request = new AlipayTradeAppPayRequest();
        // SDK已经封装掉了公共参数，这里只需要传入业务参数。以下方法为sdk的model入参方式(model和biz_content同时存在的情况下取biz_content)。
        AlipayTradeAppPayModel model = new AlipayTradeAppPayModel();
        model.setBody(describe);
        model.setSubject("App支付测试Java");
        model.setOutTradeNo(orderId);
        model.setTimeoutExpress("20m");
        model.setTotalAmount(cost);
        model.setProductCode("QUICK_MSECURITY_PAY");
        request.setBizModel(model);
        request.setNotifyUrl(AliPayConfig.ASY_URL);
        System.out.println(request);
        String orderStr = "";
        try {
            // 这里和普通的接口调用不同，使用的是sdkExecute
            AlipayTradeAppPayResponse response = alipayClient
                    .sdkExecute(request);
            orderStr = response.getBody();
            System.out.println(response.getBody());// 就是orderString
                                                    // 可以直接给客户端请求，无需再做处理。
        } catch (AlipayApiException e) {
            ret.put("code", ErrorCode.OTHER);
            ret.put("msg", e.getMessage());
            return ret;
        }
        ret.put("code", ErrorCode.SUCCESS);
        ret.put("sign", orderStr);
        return ret;
    }

支付宝结果异步回调

public static JSONObject aliPayNotify(Map<String, String[]> requestParams) {
        JSONObject result = new JSONObject();
        System.out.println("支付宝支付结果通知" + requestParams.toString());
        // 获取支付宝POST过来反馈信息
        Map<String, String> params = new HashMap<String, String>();

        for (Iterator<?> 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("ISO-8859-1"), "utf-8");
            params.put(name, valueStr);
        }
        // 获取到返回的所有参数 先判断是否交易成功trade_status 再做签名校验
        // 1、商户需要验证该通知数据中的out_trade_no是否为商户系统中创建的订单号，
        // 2、判断total_amount是否确实为该订单的实际金额（即商户订单创建时的金额），
        // 3、校验通知中的seller_id（或者seller_email)
        // 是否为out_trade_no这笔单据的对应的操作方（有的时候，一个商户可能有多个seller_id/seller_email），
        // 4、验证app_id是否为该商户本身。上述1、2、3、4有任何一个验证不通过，则表明本次通知是异常通知，务必忽略。
        try {
            // 验证签名
            boolean flag = AlipaySignature.rsaCheckV1(params,
                    AliPayConfig.ALIPAY_PUBLIC_KEY, "utf-8", "RSA2");
            if (flag) {
                if ("TRADE_SUCCESS".equals(params.get("trade_status"))
                        || "TRADE_FINISHED".equals(params.get("trade_status"))) {

                    String appId = params.get("app_id");
                    if (!appId.equals(AliPayConfig.APP_ID)) {
                        result.put("code", ErrorCode.OTHER);
                        return result;
                    }

                    // 订单金额
                    String total_amount = params.get("total_amount");
                    // 用户支付金额
                    String amount = params.get("buyer_pay_amount");
                    // 商户订单号
                    String out_trade_no = params.get("out_trade_no");
                    // 支付宝交易号
                    String trade_no = params.get("trade_no");
                    // 买家支付宝账号
                    String buyer_logon_id = params.get("buyer_logon_id");
                    // 交易状态
                    String trade_status = params.get("trade_status");
                    // 商品描述
                    String body = params.get("body");
                    // 交易创建时间
                    String gmt_create = params.get("gmt_create");
                    // 交易付款时间
                    String gmt_payment = params.get("gmt_payment");

                    JSONObject payParams = new JSONObject();
                    payParams.put("total_amount", total_amount);
                    payParams.put("amount", amount);
                    payParams.put("out_trade_no", out_trade_no);
                    payParams.put("trade_no", trade_no);
                    payParams.put("buyer_logon_id", buyer_logon_id);
                    payParams.put("trade_status", trade_status);
                    payParams.put("body", body);
                    payParams.put("gmt_create", gmt_create);
                    payParams.put("gmt_payment", gmt_payment);
                    result.put("params", payParams);
                    result.put("code", ErrorCode.SUCCESS);
                }
            } else {
                result.put("code", ErrorCode.OTHER);
                return result;
            }
        } catch (AlipayApiException e) {
            result.put("code", ErrorCode.OTHER);
            return result;
        }
        return result;
    }

退款

public String AliRefund(String out_trade_no, String trade_no,
            String out_request_no, String refund_amount) {
        AlipayClient alipayClient = new DefaultAlipayClient(
                "https://openapi.alipay.com/gateway.do", AliPayConfig.APP_ID,
                AliPayConfig.APP_PRIVATE_KEY, "json", "utf-8",
                AliPayConfig.ALIPAY_PUBLIC_KEY, "RSA2"); // 获得初始化的AlipayClient
        AlipayTradeRefundRequest request = new AlipayTradeRefundRequest();// 创建API对应的request类
        String strResponse = null;
        request.setBizContent("{" + "    \"out_trade_no\":\"" + out_trade_no
                + "\"," + "    \"trade_no\":\"" + trade_no + "\","
                + "    \"out_request_no\":\"" + out_request_no + "\","
                + "    \"refund_amount\":\"" + refund_amount + "\"" + "  }");// 设置业务参数
        AlipayTradeRefundResponse response;
        try {
            response = alipayClient.execute(request);
            if (response.isSuccess()) {
                strResponse = "退款成功";
            } else {
                strResponse = "退款失败";
            }
        } catch (AlipayApiException e) {
            strResponse = "退款出错";
        }
        return strResponse;
    }

订单查询

public void orderPayQuery(String trade_no, String out_trade_no) {
        AlipayClient alipayClient = new DefaultAlipayClient(
                "https://openapi.alipay.com/gateway.do", AliPayConfig.APP_ID,
                AliPayConfig.APP_PRIVATE_KEY, "json", "utf-8",
                AliPayConfig.ALIPAY_PUBLIC_KEY, "RSA2"); // 获得初始化的AlipayClient
        AlipayTradeQueryRequest request = new AlipayTradeQueryRequest();// 创建API对应的request类
        request.setBizContent("{" + "   \"out_trade_no\":\"" + out_trade_no
                + "\"," + "   \"trade_no\":\"" + trade_no + "\"" + "  }");// 设置业务参数
        AlipayTradeQueryResponse response;
        try {
            response = alipayClient.execute(request);
            System.out.print(response.getBody());
            Map<String, String> restmap = new HashMap<String, String>();// 返回提交支付宝订单交易查询信息
            boolean flag = false; // 查询状态
            if (response.isSuccess()) {
                // 调用成功，则处理业务逻辑
                if ("10000".equals(response.getCode())) {
                    // 订单创建成功
                    flag = true;
                    restmap.put("order_no", response.getOutTradeNo());
                    restmap.put("trade_no", response.getTradeNo());
                    restmap.put("buyer_logon_id", response.getBuyerLogonId());
                    restmap.put("trade_status", response.getTradeStatus());
                } else {
                }
            }
        } catch (AlipayApiException e) {
            e.printStackTrace();
        }
    }