golang实现微信支付v3版本的方法

openssl x509 -in 1900009191_20180326_cert.pem -noout -serial
serial=1DDE55AD98ED71D6EDD4A4A16996DE7B47773A8C

apiclient_key.p12 
apiclient_cert.pem 
apiclient_key.pem

const appId = ""   // 小程序或者公众号的appid
const mchId = ""   // 微信支付的商户id
const privateSerialNo = "" // 私钥证书号
const aesKey = ""   // 微信支付aes key

// 对消息的散列值进行数字签名
func signPKCS1v15(msg, privateKey []byte, hashType crypto.Hash) ([]byte, error) {
 block, _ := pem.Decode(privateKey)
 if block == nil {
  return nil, errors.New("private key decode error")
 }
 pri, err := x509.ParsePKCS8PrivateKey(block.Bytes)
 if err != nil {
  return nil, errors.New("parse private key error")
 }
 key, ok := pri.(*rsa.PrivateKey)
 if ok == false {
  return nil, errors.New("private key format error")
 }
 sign, err := rsa.SignPKCS1v15(cryptoRand.Reader, key, hashType, msg)
 if err != nil {
  return nil, errors.New("sign error")
 }
 return sign, nil
}
// base编码
func base64EncodeStr(src []byte) string {
 return base64.StdEncoding.EncodeToString(src)
}

func authorization(method string, paramMap map[string]interface{}, rawUrl string) (token string, err error) {
 var body string
 if len(paramMap) != 0 {
  paramJsonBytes, err := json.Marshal(paramMap)
  if err != nil {
   return token, err
  }
  body = string(paramJsonBytes)
 }
 urlPart, err := url.Parse(rawUrl)
 if err != nil {
  return token, err
 }
 canonicalUrl := urlPart.RequestURI()
 timestamp := time.Now().Unix()
 nonce := getRandomString(32)
 message := fmt.Sprintf("%s\n%s\n%d\n%s\n%s\n", method, canonicalUrl, timestamp, nonce, body)
 open, err := os.Open("/Users/apple/data/www/go/work/src/study/testwechantpay/private.pem")
 if err != nil {
  return token, err
 }
 defer open.Close()
 privateKey, err := ioutil.ReadAll(open)
 if err != nil {
  return token, err
 }
 signBytes, err := signPKCS1v15(hasha256(message), privateKey, crypto.SHA256)
 if err != nil {
  return token, err
 }
 sign := base64EncodeStr(signBytes)
 token = fmt.Sprintf("mchid=\"%s\",nonce_str=\"%s\",timestamp=\"%d\",serial_no=\"%s\",signature=\"%s\"",
  mchId, nonce, timestamp, privateSerialNo, sign)
 return token, nil
}

func decryptGCM(aesKey, nonceV, ciphertextV, additionalDataV string) ([]byte, error) {
 key := []byte(aesKey)
 nonce := []byte(nonceV)
 additionalData := []byte(additionalDataV)
 ciphertext, err := base64.StdEncoding.DecodeString(ciphertextV)
 if err != nil {
  return nil, err
 }
 block, err := aes.NewCipher(key)
 if err != nil {
  return nil, err
 }
 aesGCM, err := cipher.NewGCM(block)
 if err != nil {
  return nil, err
 }
 plaintext, err := aesGCM.Open(nil, nonce, ciphertext, additionalData)
 if err != nil {
  return nil, err
 }
 return plaintext, err
}

// 获取公钥
const publicKeyUrl = "https://api.mch.weixin.qq.com/v3/certificates"
type TokenResponse struct {
 Data []TokenResponseData `json:"data"`
}
type TokenResponseData struct {
 EffectiveTime  string    `json:"effective_time"`
 EncryptCertificate EncryptCertificate `json:"encrypt_certificate"`
 ExpireTime   string    `json:"expire_time"`
 SerialNo   string    `json:"serial_no"`
}
type EncryptCertificate struct {
 Algorithm  string `json:"algorithm"`
 AssociatedData string `json:"associated_data"`
 Ciphertext  string `json:"ciphertext"`
 Nonce   string `json:"nonce"`
}
var publicSyncMap sync.Map
// 获取公钥
func getPublicKey() (key string, err error) {
 var prepareTime int64 = 24 * 3600 * 3 // 证书提前三天过期旧证书，获取新证书
 nowTime := time.Now().Unix()
 // 读取公钥缓存数据
 cacheValueKey := fmt.Sprintf("app_id:%s:public_key:value", appId)
 cacheExpireTimeKey := fmt.Sprintf("app_id:%s:public_key:expire_time", appId)
 cacheValue, keyValueOk := publicSyncMap.Load(cacheValueKey)
 cacheExpireTime, expireTimeOk := publicSyncMap.Load(cacheExpireTimeKey)
 if keyValueOk && expireTimeOk {
  // 格式化时间
  local, _ := time.LoadLocation("Local")
  location, _ := time.ParseInLocation(time.RFC3339, cacheExpireTime.(string), local)
  // 判断是否过期，证书没有过期直接返回
  if location.Unix()-prepareTime > nowTime {
   return cacheValue.(string), nil
  }
 }
 token, err := authorization(http.MethodGet, nil, publicKeyUrl)
 if err != nil {
  return key, err
 }
 request, err := http.NewRequest(http.MethodGet, publicKeyUrl, nil)
 if err != nil {
  return key, err
 }
 request.Header.Add("Authorization", "WECHATPAY2-SHA256-RSA2048 "+token)
 request.Header.Add("User-Agent", "用户代理(https://zh.wikipedia.org/wiki/User_agent)")
 request.Header.Add("Content-type", "application/json;charset='utf-8'")
 request.Header.Add("Accept", "application/json")
 client := http.DefaultClient
 response, err := client.Do(request)
 if err != nil {
  return key, err
 }
 defer response.Body.Close()
 bodyBytes, err := ioutil.ReadAll(response.Body)
 if err != nil {
  return key, err
 }
 //fmt.Println(string(bodyBytes))
 var tokenResponse TokenResponse
 if err = json.Unmarshal(bodyBytes, &tokenResponse); err != nil {
  return key, err
 }
 for _, encryptCertificate := range tokenResponse.Data {
  // 格式化时间
  local, _ := time.LoadLocation("Local")
  location, err := time.ParseInLocation(time.RFC3339, encryptCertificate.ExpireTime, local)
  if err != nil {
   return key, err
  }
  // 判断是否过期，证书没有过期直接返回
  if location.Unix()-prepareTime > nowTime {
   decryptBytes, err := decryptGCM(aesKey, encryptCertificate.EncryptCertificate.Nonce, encryptCertificate.EncryptCertificate.Ciphertext,
    encryptCertificate.EncryptCertificate.AssociatedData)
   if err != nil {
    return key, err
   }
   key = string(decryptBytes)
   publicSyncMap.Store(cacheValueKey, key)
   publicSyncMap.Store(cacheExpireTimeKey, encryptCertificate.ExpireTime)
   return key, nil
  }
 }
 return key, errors.New("get public key error")
}

// 统一下单接口
func commonPay() (payResMap map[string]string, err error) {
 payResMap = make(map[string]string)
 amount := 10
 paramMap := make(map[string]interface{})
 paramMap["appid"] = appId
 paramMap["mchid"] = mchId
 paramMap["description"] = fmt.Sprintf("微信充值:￥%d", amount)
 paramMap["out_trade_no"] = fmt.Sprintf("test%s%s", time.Now().Format("20060102150405"), randNumber())
 paramMap["notify_url"] = "http://tools.localhost/notify"
 paramMap["amount"] = map[string]interface{}{"total": amount * 100, "currency": "CNY"}
 paramMap["payer"] = map[string]string{"openid": "opCO05utXkPQh3Vje13WjEdQpAZ4"}
 token, err := authorization(http.MethodPost, paramMap, commonPayUrl)
 if err != nil {
  return payResMap, err
 }
 marshal, _ := json.Marshal(paramMap)
 request, err := http.NewRequest(http.MethodPost, commonPayUrl, bytes.NewReader(marshal))
 if err != nil {
  return payResMap, err
 }
 request.Header.Add("Authorization", "WECHATPAY2-SHA256-RSA2048 "+token)
 request.Header.Add("User-Agent", "用户代理(https://zh.wikipedia.org/wiki/User_agent)")
 request.Header.Add("Content-type", "application/json;charset='utf-8'")
 request.Header.Add("Accept", "application/json")
 client := http.DefaultClient
 response, err := client.Do(request)
 if err != nil {
  return payResMap, err
 }
 defer func() {
  response.Body.Close()
 }()
 bodyBytes, err := ioutil.ReadAll(response.Body)
 if err != nil {
  return payResMap, err
 }
 if err = json.Unmarshal(bodyBytes, &payResMap); err != nil {
  return payResMap, err
 }
 if payResMap["prepay_id"] == "" {
  return payResMap, errors.New("code:" + payResMap["code"] + "err:" + payResMap["message"])
 }
 return payResMap, nil
}

func jsApi(payResMap map[string]string) (payJson string, err error) {
 payMap := make(map[string]string)
 timeStamp := time.Now().Unix()
 nonce := getRandomString(32)
 packageStr := "prepay_id=" + payResMap["prepay_id"]
 payMap["appId"] = appId
 payMap["timeStamp"] = fmt.Sprintf("%v", timeStamp)
 payMap["nonceStr"] = nonce
 payMap["package"] = packageStr
 // 签名
 message := fmt.Sprintf("%s\n%s\n%s\n%s\n", appId, fmt.Sprintf("%v", timeStamp), nonce, packageStr)
 open, err := os.Open("/Users/apple/data/www/go/work/src/study/testwechantpay/private.pem")
 if err != nil {
  return payJson, err
 }
 defer open.Close()
 privateKey, err := ioutil.ReadAll(open)
 if err != nil {
  return payJson, err
 }
 signBytes, err := signPKCS1v15(hasha256(message), privateKey, crypto.SHA256)
 if err != nil {
  return payJson, err
 }
 sign := base64EncodeStr(signBytes)
 payMap["signType"] = sign
 payMap["paySign"] = "RSA"
 payJsonBytes, err := json.Marshal(payMap)
 if err != nil {
  return payJson, err
 }
 payJson = string(payJsonBytes)
 return payJson, nil
}

<script type="text/javascript" src="__STATIC__/frontend/js/jquery.min.js"></script>
<script type="text/javascript" src="http://res.wx.qq.com/open/js/jweixin-1.6.0.js"></script>
<script> 
 $(function () {
  $(".am-btn").click(function () {
   var score = $(".score div input:checked").val();
   $.post("发起微信支付后端接口URL", {"score": score}, function (res) {
    if (res.status === 500) {
     alert(res.message);
     return;
    }
    if (typeof WeixinJSBridge == "undefined") {
     if (document.addEventListener) {
      document.addEventListener('WeixinJSBridgeReady', onBridgeReady, false);
     } else if (document.attachEvent) {
      document.attachEvent('WeixinJSBridgeReady', onBridgeReady);
      document.attachEvent('onWeixinJSBridgeReady', onBridgeReady);
     }
    } else {
     onBridgeReady(res);
    }
   })
  })
  function onBridgeReady(param) {
   var orderId = param.data.orderId;
   WeixinJSBridge.invoke('getBrandWCPayRequest', {
     "appId": param.data.appId,
     "timeStamp": param.data.timeStamp,
     "nonceStr": param.data.nonceStr,
     "package": param.data.package,
     "signType": param.data.signType,
     "paySign": param.data.paySign
    },
    function (res) {
     if (res.err_msg === "get_brand_wcpay_request:ok") {
      window.location.href = "{:url('index/order/successful')}?order_id=" + orderId;
     }
    });
  }
 })
 </script>

//验证数字签名
func VerifyRsaSign(msg []byte, sign []byte, publicStr []byte, hashType crypto.Hash) bool {
 //pem解码
 block, _ := pem.Decode(publicStr)
 //x509解码
 publicKeyInterface, err := x509.ParseCertificate(block.Bytes)
 if err != nil {
  panic(err)
 }
 publicKey := publicKeyInterface.PublicKey.(*rsa.PublicKey)
 //验证数字签名
 err = rsa.VerifyPKCS1v15(publicKey, hashType, msg, sign) //crypto.SHA1
 return err == nil
}
// 验证签名
func notifyValidate(timeStamp ,nonce,rawPost,signature string) (bool, error) {
 signature = base64DecodeStr(signature)
 message := fmt.Sprintf("%s\n%s\n%s\n", timeStamp, nonce, rawPost)
 publicKey, err := getPublicKey()
 if err != nil {
  return false, err
 }
 return VerifyRsaSign(hasha256(message), []byte(signature), []byte(publicKey), crypto.SHA256), nil
}

type NotifyResponse struct {
 CreateTime string   `json:"create_time"`
 Resource NotifyResource `json:"resource"`
}
type NotifyResource struct {
 Ciphertext  string `json:"ciphertext"`
 AssociatedData string `json:"associated_data"`
 Nonce   string `json:"nonce"`
}
func notifyDecrypt(rawPost string) (decrypt string, err error) {
 var notifyResponse NotifyResponse
 if err = json.Unmarshal([]byte(rawPost), &notifyResponse); err != nil {
  return decrypt, err
 }
 decryptBytes, err := decryptGCM(aesKey, notifyResponse.Resource.Nonce, notifyResponse.Resource.Ciphertext,
  notifyResponse.Resource.AssociatedData)
 if err != nil {
  return decrypt, err
 }
 decrypt = string(decryptBytes)
 return decrypt, nil
}

const searchTradeUrl = "https://api.mch.weixin.qq.com/v3/pay/transactions/out-trade-no/%s?mchid=%s"
// 查询交易
func searchTrade(orderId string) (trade string, err error) {
 rawUrl := fmt.Sprintf(searchTradeUrl, orderId, mchId)
 token, err := authorization(http.MethodGet, nil, rawUrl)
 if err != nil {
  return trade, err
 }
 request, err := http.NewRequest(http.MethodGet, rawUrl, nil)
 if err != nil {
  return trade, err
 }
 request.Header.Add("Authorization", "WECHATPAY2-SHA256-RSA2048 "+token)
 request.Header.Add("User-Agent", "用户代理(https://zh.wikipedia.org/wiki/User_agent)")
 request.Header.Add("Content-type", "application/json;charset='utf-8'")
 request.Header.Add("Accept", "application/json")
 client := http.DefaultClient
 response, err := client.Do(request)
 if err != nil {
  return trade, err
 }
 defer response.Body.Close()
 bodyBytes, err := ioutil.ReadAll(response.Body)
 if err != nil {
  return trade, err
 }
 return string(bodyBytes), nil
}

const refundUrl = "https://api.mch.weixin.qq.com/v3/refund/domestic/refunds"
func refundTrade(orderId string, amount float64) (trade string, err error) {
 paramMap := make(map[string]interface{})
 paramMap["out_trade_no"] = orderId
 paramMap["out_refund_no"] = orderId + "-1"
 paramMap["amount"] = map[string]interface{}{"refund": amount * 100, "total": amount * 100, "currency": "CNY"}
 token, err := authorization(http.MethodPost, paramMap, refundUrl)
 if err != nil {
  return trade, err
 }
 marshal, _ := json.Marshal(paramMap)
 request, err := http.NewRequest(http.MethodPost, refundUrl, bytes.NewReader(marshal))
 if err != nil {
  return trade, err
 }
 request.Header.Add("Authorization", "WECHATPAY2-SHA256-RSA2048 "+token)
 request.Header.Add("User-Agent", "用户代理(https://zh.wikipedia.org/wiki/User_agent)")
 request.Header.Add("Content-type", "application/json;charset='utf-8'")
 request.Header.Add("Accept", "application/json")
 client := http.DefaultClient
 response, err := client.Do(request)
 if err != nil {
  return trade, err
 }
 defer func() {
  response.Body.Close()
 }()
 bodyBytes, err := ioutil.ReadAll(response.Body)
 if err != nil {
  return trade, err
 }
 return string(bodyBytes), nil
}