update

README.md

@@ -283,8 +283,8 @@ fmt.Println("Watermark:", phone.Watermark)
 ```go
 rsp := new(gopay.WeChatNotifyResponse) //回复微信的数据
 
-rsp.ReturnCode = "SUCCESS"
-rsp.ReturnMsg = "OK"
+rsp.ReturnCode = gopay.SUCCESS
+rsp.ReturnMsg = gopay.OK
 
 return c.String(http.StatusOK, rsp.ToXmlString())
 ```

README_EN.md

@@ -280,8 +280,8 @@ fmt.Println("Watermark:", phone.Watermark)
 ```go
 rsp := new(gopay.WeChatNotifyResponse) // the struct return WeChat Platform
 
-rsp.ReturnCode = "SUCCESS"
-rsp.ReturnMsg = "OK"
+rsp.ReturnCode = gopay.SUCCESS
+rsp.ReturnMsg = gopay.OK
 
 return c.String(http.StatusOK, rsp.ToXmlString())
 ```

examples/alipay/alipay_AliPayTradePrecreate.go

@@ -19,7 +19,7 @@ func AliPayTradePrecreate() {
 	//请求参数
 	body := make(gopay.BodyMap)
 	body.Set("subject", "预创建创建订单")
-	body.Set("out_trade_no", "GZ201901301040355703")
+	body.Set("out_trade_no", "GZ201907301040355704")
 	body.Set("total_amount", "100")
 	//创建订单
 	aliRsp, err := client.AliPayTradePrecreate(body)

message.go

@@ -3,6 +3,7 @@ package gopay
 const (
 	SUCCESS = "SUCCESS"
 	FAIL    = "FAIL"
+	OK      = "OK"
 )
 
 type ReturnMessage struct {