调用Web服务：请求因HTTP状态401失败：Unauthorized

IRSpiderWS.SaveSpiderData saveSpider = new IRSpiderWS.SaveSpiderData();
            saveSpider.Url = System.Configuration.ConfigurationSettings.AppSettings["IRSpiderWS"];
//如下是设置系统认证
            saveSpider.Credentials = System.Net.CredentialCache.DefaultCredentials;