idhttp+tidmultpartfromdatastream

参阅：https://www.cnblogs.com/ClaireWu/p/12487028.html

function xxx.UploadFile(const sAccessToken, sFile, sFileType: string):string;

var

  IdHttp: TIdHTTP;

  MutPartForm: TIdMultiPartFormDataStream;

  Ms: TStringStream;

  sTmp: string;

  LStream: TIdReadFileExclusiveStream;

  SSLIO: TIdSSLIOHandlerSocketOpenSSL;

begin

  Result := '';

  try

    Ms := TStringStream.Create('', TEncoding.UTF8);

    IdHttp := TIdHttp.Create(nil);

    IdHttp.ReadTimeout := 30000;

    MutPartForm := TIdMultiPartFormDataStream.Create;

    LStream := TIdReadFileExclusiveStream.Create(sFile);

    SSLIO := TIdSSLIOHandlerSocketOpenSSL.Create(nil);

    try

      IdHttp.AllowCookies    := True;

      IdHttp.HandleRedirects := True; //允许重定向

      SSLIO.SSLOptions.Method:=sslvTLSv1;

      SSLIO.SSLOptions.Mode := sslmClient;

      IdHttp.IOHandler := SSLIO;

      // Http1.1

      IdHttp.HTTPOptions := IdHttp.HTTPOptions + [hoKeepOrigProtocol];

      IdHttp.ProtocolVersion := pv1_1;

      MutPartForm.AddObject('media', 'application/octet-stream', LStream, ExtractFileName(sFile));

      sTmp := Format('http://qyapi.weixin.qq.com/cgi-bin/media/upload?access_token=%s&type=%s',[sAccessToken, sFileType]);

      IdHttp.Post(sTmp, MutPartForm, Ms);

      Result := Ms.DataString;

    finally

      LStream.Free;

      Ms.Free;

      IdHttp.Free;

      MutPartForm.Free;

      SSLIO.Free;

    end;

  except

    on E: Exception do Result := E.Message;

  end;

end;