public class AlipayConfig{
 // 应用ID,您的APPID，收款账号既是您的APPID对应支付宝账号
 public static String app_id = "2016091600523365";
 
 // 商户私钥，您的PKCS8格式RSA2私钥
 public static String merchant_private_key = "商户私钥";
 // 支付宝公钥,查看地址：https://openhome.alipay.com/platform/keyManage.htm 对应APPID下的支付宝公钥。
 public static String alipay_public_key = "支付宝公钥";
 // 服务器异步通知页面路径 需http://格式的完整路径，不能加?id=123这类自定义参数，必须外网可以正常访问
 public static String notify_url = "http://工程公网访问地址";
 
 // 页面跳转同步通知页面路径 需http://格式的完整路径，不能加?id=123这类自定义参数，必须外网可以正常访问
 public static String return_url = "http://工程公网访问地址";
 
 // 签名方式
 public static String sign_type = "RSA2";
 
 // 字符编码格式
 public static String charset = "utf-8";
 
 // 支付宝网关
 public static String gatewayUrl = "https://openapi.alipaydev.com/gateway.do";
 
 // 支付宝网关
 public static String log_path = "C:\\";
 
 
//↑↑↑↑↑↑↑↑↑↑请在这里配置您的基本信息↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑
 
 /**
  * 写日志，方便测试（看网站需求，也可以改成把记录存入数据库）
  * @param sWord 要写入日志里的文本内容
  */
 public static void logResult(String sWord) {
  FileWriter writer = null;
  try {
   writer = new FileWriter(log_path + "alipay_log_" + System.currentTimeMillis()+".txt");
   writer.write(sWord);
  } catch (Exception e) {
   e.printStackTrace();
  } finally {
   if (writer != null) {
    try {
     writer.close();
    } catch (IOException e) {
     e.printStackTrace();
    }
   }
  }
 }
}

@RequestMapping("ali")
 public void ali(HttpServletResponse response, HttpServletRequest request) throws IOException, AlipayApiException {
  ordersService.ali(response,request);
 }

@Override
public void ali(HttpServletResponse response, HttpServletRequest request) throws AlipayApiException, IOException{
  //设置编码
  response.setContentType("text/html;charset=utf-8");
 
  PrintWriter out = response.getWriter();
  //获得初始化的AlipayClient
  AlipayClient alipayClient = new DefaultAlipayClient(AlipayConfig.gatewayUrl, AlipayConfig.app_id, AlipayConfig.merchant_private_key, "json", AlipayConfig.charset, AlipayConfig.alipay_public_key, AlipayConfig.sign_type);
  //设置请求参数
  AlipayTradePagePayRequest aliPayRequest = new AlipayTradePagePayRequest();
  aliPayRequest.setReturnUrl(AlipayConfig.return_url);
  aliPayRequest.setNotifyUrl(AlipayConfig.notify_url);
 
  //商户订单号，后台可以写一个工具类生成一个订单号，必填
  String order_number = new String(订单号);
  //付款金额，从前台获取，必填
  String total_amount = new String(付款金额);
  //订单名称，必填
  String subject = new String("支付宝沙箱支付（名称随便起）");
  aliPayRequest.setBizContent("{\"out_trade_no\":\"" + order_number + "\","
    + "\"total_amount\":\"" + total_amount + "\","
    + "\"subject\":\"" + subject + "\","
    + "\"product_code\":\"FAST_INSTANT_TRADE_PAY\"}");
  //请求
  String result = alipayClient.pageExecute(aliPayRequest).getBody();
  //输出
  out.println(result);//以下写自己的订单代码
}

PrintWriter out = response.getWriter();
out.println(result);

//退款
@Override
public void refund(HttpServletResponse response,HttpSession session) throws IOException, AlipayApiException {
 response.setContentType("text/html;charset=utf-8");
 PrintWriter out = response.getWriter();
 //获得初始化的AlipayClient
 AlipayClient alipayClient = new DefaultAlipayClient(AlipayConfig.gatewayUrl, AlipayConfig.app_id, AlipayConfig.merchant_private_key, "json", AlipayConfig.charset, AlipayConfig.alipay_public_key, AlipayConfig.sign_type);
 //设置请求参数
 AlipayTradeRefundRequest alipayRequest = new AlipayTradeRefundRequest();
 //商户订单号，必填
 String out_trade_no = new String(订单号);
 //需要退款的金额，该金额不能大于订单金额，必填
 String refund_amount = new String(退款金额);
 //标识一次退款请求，同一笔交易多次退款需要保证唯一，如需部分退款，则此参数必传
 String out_request_no = new String(UUID.randomUUID().toString());
 
 alipayRequest.setBizContent("{\"out_trade_no\":\""+ out_trade_no +"\","
   + "\"refund_amount\":\""+ refund_amount +"\","
   + "\"out_request_no\":\""+ out_request_no +"\"}");
 //请求
 String result = alipayClient.execute(alipayRequest).getBody();
 //输出
 out.println(result);以下写自己的订单退款代码
}