// DownloadToWriter 下载多媒体到 io.Writer.
// 对于视频素材, 先通过 GetVideo 得到 Video 信息, 然后通过 Video.DownloadURL 来下载
func DownloadToWriter(clt *core.Client, mediaId string, writer io.Writer) (written int64, err error) {
httpClient := clt.HttpClient
if httpClient == nil {
httpClient = http.DefaultClient
}
var request = struct {
MediaId string `json:"media_id"`
}{
MediaId: mediaId,
}
requestBodyBytes, err := json.Marshal(&request)
if err != nil {
return
}
var errorResult core.Error
// 先读取 64bytes 内容来判断返回的是不是错误信息
// {"errcode":40007,"errmsg":"invalid media_id"}
var buf = make([]byte, 64)
token, err := clt.Token()
if err != nil {
return
}
hasRetried := false
RETRY:
finalURL := "https://api.weixin.qq.com/cgi-bin/material/get_material?access_token=" + url.QueryEscape(token)
written, err = httpDownloadToWriter(httpClient, finalURL, requestBodyBytes, buf, writer, &errorResult)
if err != nil {
return
}
if written > 0 {
return
}
switch errorResult.ErrCode {
case core.ErrCodeOK:
return // 基本不会出现
case core.ErrCodeInvalidCredential, core.ErrCodeAccessTokenExpired:
retry.DebugPrintError(errorResult.ErrCode, errorResult.ErrMsg, token)
if !hasRetried {
hasRetried = true
errorResult = core.Error{}
if token, err = clt.RefreshToken(token); err != nil {
return
}
retry.DebugPrintNewToken(token)
goto RETRY
}
retry.DebugPrintFallthrough(token)
fallthrough
default:
err = &errorResult
return
}
}
// DownloadToWriter 下载多媒体到 io.Writer.
// 请注意, 视频文件不支持下载
func DownloadToWriter(clt *core.Client, mediaId string, writer io.Writer) (written int64, err error) {
httpClient := clt.HttpClient
if httpClient == nil {
httpClient = http.DefaultClient
}
var incompleteURL = "https://api.weixin.qq.com/cgi-bin/media/get?media_id=" + url.QueryEscape(mediaId) + "&access_token="
var errorResult core.Error
token, err := clt.Token()
if err != nil {
return
}
hasRetried := false
RETRY:
finalURL := incompleteURL + url.QueryEscape(token)
written, err = httpDownloadToWriter(httpClient, finalURL, writer, &errorResult)
if err != nil {
return
}
if written > 0 {
return
}
switch errorResult.ErrCode {
case core.ErrCodeOK:
return // 基本不会出现
case core.ErrCodeInvalidCredential, core.ErrCodeAccessTokenExpired:
retry.DebugPrintError(errorResult.ErrCode, errorResult.ErrMsg, token)
if !hasRetried {
hasRetried = true
errorResult = core.Error{}
if token, err = clt.RefreshToken(token); err != nil {
return
}
retry.DebugPrintNewToken(token)
goto RETRY
}
retry.DebugPrintFallthrough(token)
fallthrough
default:
err = &errorResult
return
}
}