小程序微信支付完整demo，包含退款

//支付
  pay: function(e){
    var that = this;
    if(that.data.number == ‘‘){
      wx.showToast({
        title: ‘请填写支付金额!‘,
        icon: ‘none‘,
        duration: 2000
      })
      return;
    }
    util.getOpenid(function(openid){
      wx.request({
        url: app.globalData.baseUrl + ‘/pay/pay.html‘, 
        header: {
          ‘content-type‘: ‘application/x-www-form-urlencoded‘
        },
        method: ‘POST‘,
        data: {
          totalFee: that.data.number,
          openid: openid
        },
        success (res) {
          var data = res.data.data;
          wx.requestPayment(
            {
            ‘timeStamp‘: data.timeStamp,
            ‘nonceStr‘: data.nonce_str,
            ‘package‘: ‘prepay_id=‘+data.prepay_id,
            ‘signType‘: ‘MD5‘,
            ‘paySign‘: data.sign,
            ‘success‘:function(res){
              wx.showToast({
                title: ‘支付成功‘,
                icon: ‘none‘,
                duration: 2000
              })
            },
            ‘fail‘:function(res){
              wx.showToast({
                title: ‘支付失败‘,
                icon: ‘none‘,
                duration: 2000
              })
            }
          })
        }
      })
    });

/**
	 * 支付(api)
	 */
	@RequestMapping(value="/pay")
	@ResponseBody
	public ResultInfo<Object> pay(
			HttpServletRequest request, 
			double totalFee,
			String openid){
		try {
			final String appId = CustomPropertyConfigurer.getProperty("weixin.mini.appid");
			final String key = CustomPropertyConfigurer.getProperty("weixin.mini.key");
			final String mch_id = CustomPropertyConfigurer.getProperty("weixin.mini.mch_id");
			final String notify_url = CustomPropertyConfigurer.getProperty("weixin.mini.notify_url");
			final String ip = CustomPropertyConfigurer.getProperty("ip");
			//out_trade_no是自定义的系统内部订单号
			String out_trade_no = new DateTime().toString("yyyyMMddHHmmss") + String.valueOf((int)((Math.random()*9+1)*1000));
			Order order = new Order();
			order.setAppid(appId);
			order.setMch_id(mch_id);
			order.setNonce_str(RandomStringGenerator.getRandomStringByLength(32));
			order.setBody("下单-支付");
			order.setOut_trade_no(out_trade_no);
			order.setTotal_fee((int)(totalFee * 100));//支付金额(分)
			order.setSpbill_create_ip(ip);
			order.setNotify_url(notify_url);
			order.setTrade_type("JSAPI");
			order.setSign_type("MD5");
			order.setOpenid(openid);
			//生成签名
			String sign = Signature.getSign(order, key);
			order.setSign(sign);
			
			String result = HttpRequest.sendPost("https://api.mch.weixin.qq.com/pay/unifiedorder", order, false, null, null);
			System.out.println(result);
			L.info("---------下单返回:"+result);
			XStream xStream = new XStream();
			xStream.ignoreUnknownElements();
			xStream.alias("xml", OrderReturnInfo.class); 
			OrderReturnInfo returnInfo = (OrderReturnInfo)xStream.fromXML(result);
			if(returnInfo.getResult_code().equals("SUCCESS") && returnInfo.getReturn_code().equals("SUCCESS")){
				//下单成功，此处是你的业务代码
				System.out.print("下单成功");
			}
				
			//生成签名
			final String timeStamp = String.valueOf(System.currentTimeMillis()/1000);
			sign = "appId="+appId+"&nonceStr="+order.getNonce_str()+"&package=prepay_id="+returnInfo.getPrepay_id()+"&signType=MD5&timeStamp="+timeStamp+"&key="+key;
			sign = MD5.MD5Encode(sign).toUpperCase();
			JSONObject jsonObject = new JSONObject();
			jsonObject.put("nonce_str", order.getNonce_str());
			jsonObject.put("prepay_id", returnInfo.getPrepay_id());
			jsonObject.put("sign", sign);
			jsonObject.put("timeStamp", timeStamp);
			return new ResultInfo<Object>(0, jsonObject);
		} catch (Exception e) {
			e.printStackTrace();
			L.error("-------------", e);
		}
		return new ResultInfo<Object>(1000, "未知错误"); 
	}

/**
	 * 申请退款
	 */
	@RequestMapping(value="/apply")
	@ResponseBody
	public Object apply(
			HttpServletRequest request,
			double refundFee,
			String out_trade_no){
		try {
			final String appId = CustomPropertyConfigurer.getProperty("weixin.mini.appid");
			final String mch_id = CustomPropertyConfigurer.getProperty("weixin.mini.mch_id");
			final String refund_notify_url = CustomPropertyConfigurer.getProperty("weixin.mini.refund_notify_url");
			final String key = CustomPropertyConfigurer.getProperty("weixin.mini.key");
			WxRefund wxRefund = new WxRefund();
			wxRefund.setAppid(appId);
			
			wxRefund.setMch_id(mch_id);
			wxRefund.setNonce_str(RandomStringGenerator.getRandomStringByLength(32));
			wxRefund.setOut_trade_no(out_trade_no);
			wxRefund.setOut_refund_no(out_trade_no);
			wxRefund.setRefund_fee((int)(refundFee*100));
			wxRefund.setTotal_fee((int)(refundFee*100));
			wxRefund.setNotify_url(refund_notify_url);
			//生成签名
			String sign = Signature.getSign(wxRefund, key);
			wxRefund.setSign(sign);
			
			//获取证书
			String certFile = request.getServletContext().getRealPath("/") + "cert/apiclient_cert.p12"; 
			String result = HttpRequest.sendPost("https://api.mch.weixin.qq.com/secapi/pay/refund", wxRefund, true, mch_id, certFile);
			L.info("---------退款返回:"+result);
			System.out.println(result);
			XStream xStream = new XStream();
			xStream.ignoreUnknownElements();
			xStream.alias("xml", RefundReturnInfo.class); 
			RefundReturnInfo returnInfo = (RefundReturnInfo)xStream.fromXML(result);
			if(returnInfo.getResult_code().equals("SUCCESS") && returnInfo.getReturn_code().equals("SUCCESS")){
				return true;
			}
			return new ResultInfo<Object>(0, null);
		} catch (Exception e) {
			e.printStackTrace();
			L.error("------------------------", e);
		}
		return new ResultInfo<Object>(1000, "未知错误"); 
	}