java实现支付宝退款功能

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
 
import com.alipay.api.AlipayClient;
import com.alipay.api.DefaultAlipayClient;
import com.alipay.api.domain.AlipayTradeRefundModel;
import com.alipay.api.request.AlipayTradeRefundRequest;
import com.alipay.api.response.AlipayTradeRefundResponse;
 
public class AlipayUtil {
 
 private static final Logger LOGGER = LoggerFactory.getLogger(AlipayUtil.class); 
 private static String APP_ID = "234789720984098";
 
 //支付宝退款请求的网关
 private static String requestUrl = "https://openapi.alipay.com/gateway.do";
 //用户自己生成的私钥
 private static String APP_PRIVATE_KEY = "随机字符，见文档";
 //支付宝公钥
 private static String ALIPAY_PUBLIC_KEY = "从支付宝中获得";
 
 //编码级别
 private static String CHARSET = "UTF-8";
 
 public static String refundOrder(AliRefundTO aliRefundTO){
 System.out.println("开始调用支付宝加密******************************************************");
 //实例化客户端
  AlipayClient alipayClient = new DefaultAlipayClient(requestUrl, APP_ID, APP_PRIVATE_KEY, "json", CHARSET, ALIPAY_PUBLIC_KEY, "RSA2");
  //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)。
  AlipayTradeRefundModel refundModel = new AlipayTradeRefundModel();
  refundModel.setTradeNo(aliRefundTO.getTrade_no());
  refundModel.setRefundAmount(aliRefundTO.getRefund_amount());
  refundModel.setRefundReason("商品退款");
  //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
  AlipayTradeRefundRequest request = new AlipayTradeRefundRequest();
  request.setBizModel(refundModel);
  try{
  AlipayTradeRefundResponse response = alipayClient.execute(request);
  System.out.println(response.getMsg()+"\n");
  System.out.println(response.getBody());
  }catch(Exception e){
  e.printStackTrace();
  LOGGER.error("支付宝退款错误！",e.getMessage());  
  } 
  return "";  
 }
 
 public static void main(String[] arg){
 AliRefundTO aliRefundTO=new AliRefundTO();
 aliRefundTO.setRefund_amount("0.01");
 aliRefundTO.setTrade_no("2018050421001004310518105890");
 String res=refundOrder(aliRefundTO);
 }
}