将获取AccessToken和jsTicket单独抽象为interface

credential/default_access_token.go

@@ -0,0 +1,97 @@
+package credential
+
+import (
+	"encoding/json"
+	"fmt"
+	"sync"
+	"time"
+
+	"github.com/silenceper/wechat/v2/cache"
+	"github.com/silenceper/wechat/v2/util"
+)
+
+const (
+	//AccessTokenURL 获取access_token的接口
+	accessTokenURL = "https://api.weixin.qq.com/cgi-bin/token"
+	//CacheKeyOfficialAccountPrefix 微信公众号cache key前缀
+	CacheKeyOfficialAccountPrefix = "gowechat_officialaccount_"
+)
+
+//DefaultAccessToken 默认AccessToken 获取
+type DefaultAccessToken struct {
+	appID           string
+	appSecret       string
+	cacheKeyPrefix  string
+	cache           cache.Cache
+	accessTokenLock *sync.Mutex
+}
+
+//NewDefaultAccessToken new DefaultAccessToken
+func NewDefaultAccessToken(appID, appSecret, cacheKeyPrefix string, cache cache.Cache) AccessTokenHandle {
+	if cache == nil {
+		panic("cache is ineed")
+	}
+	return &DefaultAccessToken{
+		appID:           appID,
+		appSecret:       appSecret,
+		cache:           cache,
+		cacheKeyPrefix:  cacheKeyPrefix,
+		accessTokenLock: new(sync.Mutex),
+	}
+}
+
+//ResAccessToken struct
+type ResAccessToken struct {
+	util.CommonError
+
+	AccessToken string `json:"access_token"`
+	ExpiresIn   int64  `json:"expires_in"`
+}
+
+//GetAccessToken 获取access_token,先从cache中获取，没有则从服务端获取
+func (ak *DefaultAccessToken) GetAccessToken() (accessToken string, err error) {
+	//加上lock，是为了防止在并发获取token时，cache刚好失效，导致从微信服务器上获取到不同token
+	ak.accessTokenLock.Lock()
+	defer ak.accessTokenLock.Unlock()
+
+	accessTokenCacheKey := fmt.Sprintf("%s_access_token_%s", ak.cacheKeyPrefix, ak.appID)
+	val := ak.cache.Get(accessTokenCacheKey)
+	if val != nil {
+		accessToken = val.(string)
+		return
+	}
+
+	//cache失效，从微信服务器获取
+	var resAccessToken ResAccessToken
+	resAccessToken, err = GetTokenFromServer(ak.appID, ak.appSecret)
+	if err != nil {
+		return
+	}
+
+	expires := resAccessToken.ExpiresIn - 1500
+	err = ak.cache.Set(accessTokenCacheKey, resAccessToken.AccessToken, time.Duration(expires)*time.Second)
+	if err != nil {
+		return
+	}
+	accessToken = resAccessToken.AccessToken
+	return
+}
+
+//GetTokenFromServer 强制从微信服务器获取token
+func GetTokenFromServer(appID, appSecret string) (resAccessToken ResAccessToken, err error) {
+	url := fmt.Sprintf("%s?grant_type=client_credential&appid=%s&secret=%s", accessTokenURL, appID, appSecret)
+	var body []byte
+	body, err = util.HTTPGet(url)
+	if err != nil {
+		return
+	}
+	err = json.Unmarshal(body, &resAccessToken)
+	if err != nil {
+		return
+	}
+	if resAccessToken.ErrMsg != "" {
+		err = fmt.Errorf("get access_token error : errcode=%v , errormsg=%v", resAccessToken.ErrCode, resAccessToken.ErrMsg)
+		return
+	}
+	return
+}